Chinese

@techreport{young1948on14,
    author = "Young, C. C",
    title = "On two new saurischians from Lufeng, Yunnan",
    year = "1948",
    howpublished = "Bulletin of the Geological Society of China, v. 28, p. 75-90",
    note = "talkorigins\_source = {true}; raw\_reference = {Young, C. C., 1948, On two new saurischians from Lufeng, Yunnan: Bulletin of the Geological Society of China, v. 28, p. 75-90.}"
}

@misc{dong1973dinosaurs1,
    author = "Dong, Z",
    title = "Dinosaurs from Wuerho",
    year = "1973",
    howpublished = "Memoirs of the Institute of Vertebrate Paelontology and Paleoanthropology, Academy Sinica, v. 11, p. 45-52; In Chinese",
    note = "talkorigins\_source = {true}; raw\_reference = {Dong, Z., 1973, Dinosaurs from Wuerho: Memoirs of the Institute of Vertebrate Paelontology and Paleoanthropology, Academy Sinica, v. 11, p. 45-52; In Chinese.}"
}

@misc{dong1978note3,
    author = "Dong, Z. and Chang, L. and Li, X. and Zhou, S",
    title = "Note on a new carnosaur (Yangchuanosaurus shangyouensis gen. et sp. nov.) from the Jurassic of Yangchuan district, Szechuan Province",
    year = "1978",
    howpublished = "Kexue Tongboa, v. 23, no. 5, p. 302- 304; In Chinese",
    note = "talkorigins\_source = {true}; raw\_reference = {Dong, Z., Chang, L., Li, X., and Zhou, S., 1978, Note on a new carnosaur (Yangchuanosaurus shangyouensis gen. et sp. nov.) from the Jurassic of Yangchuan district, Szechuan Province: Kexue Tongboa, v. 23, no. 5, p. 302- 304; In Chinese.}"
}

Abstract This, the first detailed description, interpretation and reconstruction of Odaraia alata, is based on all 29 known specimens. These include material of Eurysaces pielus Simonetta and Delle Cave, 1975, which is synonymized with O. alata herein. The head bore a pair of large eyes anteriorly and a paired mandible posteriorly. Features between these are poorly defined and the number of limb-bearing cephalic somites is unknown. The carapace was bivalved and essentially tubular in configuration, enclosing most of the body anteriorly. The trunk included up to at least 45 uniform short wide limb-bearing somites. The trunk appendages were biramous (with the possible exception of the first two), with an outer lamellate branch projecting dorsad of a segmented, spinose and apparently sometimes bifurcate inner branch which shows some evidence of variation along the trunk. The telson bore three large flukes, two projecting laterally and one vertically. The evidence suggests that O. alata fed by employing the carapace as a filter chamber within which the appendages, which trapped small pelagic animals, were confined. The arthropod probably swam on its back, using the appendages. Although the flukes did not articulate proximally, the telson appears to have been well adapted as a stabilizing and steering organ. O. alata shows some similarities to the Crustacea, particularly the Branchiopoda, but the preservation of the features of the cephalon is inadequate to allow its affinities to be determined unequivocally. It is classified in the family Odaraidae Simonetta and Delle Cave, 1975, but assignment to a higher taxon within the arthropods is not considered to be justified.

@article{doi101098rstb19810007,
    author = "Briggs, Derek E. G.",
    title = "The arthropod Odaraia alata Walcott, Middle Cambrian, Burgess Shale, British Columbia",
    year = "1981",
    journal = "Philosophical transactions of the Royal Society of London. Series B, Biological sciences",
    abstract = "Abstract This, the first detailed description, interpretation and reconstruction of Odaraia alata, is based on all 29 known specimens. These include material of Eurysaces pielus Simonetta and Delle Cave, 1975, which is synonymized with O. alata herein. The head bore a pair of large eyes anteriorly and a paired mandible posteriorly. Features between these are poorly defined and the number of limb-bearing cephalic somites is unknown. The carapace was bivalved and essentially tubular in configuration, enclosing most of the body anteriorly. The trunk included up to at least 45 uniform short wide limb-bearing somites. The trunk appendages were biramous (with the possible exception of the first two), with an outer lamellate branch projecting dorsad of a segmented, spinose and apparently sometimes bifurcate inner branch which shows some evidence of variation along the trunk. The telson bore three large flukes, two projecting laterally and one vertically. The evidence suggests that O. alata fed by employing the carapace as a filter chamber within which the appendages, which trapped small pelagic animals, were confined. The arthropod probably swam on its back, using the appendages. Although the flukes did not articulate proximally, the telson appears to have been well adapted as a stabilizing and steering organ. O. alata shows some similarities to the Crustacea, particularly the Branchiopoda, but the preservation of the features of the cephalon is inadequate to allow its affinities to be determined unequivocally. It is classified in the family Odaraidae Simonetta and Delle Cave, 1975, but assignment to a higher taxon within the arthropods is not considered to be justified.",
    url = "https://doi.org/10.1098/rstb.1981.0007",
    doi = "10.1098/rstb.1981.0007",
    openalex = "W2016692926",
    references = "doi101017s0022112070001830, doi10108003115517908565437, doi101098rstb19750033, doi101098rstb19780005, doi101098rstb19790006, doi10182618200049639197506, doi1023072412988, doi105281zenodo15992748, doi105281zenodo16490103, doi105962bhlpart4119"
}

@misc{dong1983the5,
    author = "Dong, Z. and Zhou, S. and Zhang, Y",
    title = "The dinosaurian remains from Sichuan Basin, China",
    year = "1983",
    howpublished = "Palaeontographica Sinica, v. 162, p. 1-147; In Chinese",
    note = "talkorigins\_source = {true}; raw\_reference = {Dong, Z., Zhou, S., and Zhang, Y., 1983, The dinosaurian remains from Sichuan Basin, China: Palaeontographica Sinica, v. 162, p. 1-147; In Chinese.}"
}

@misc{rukang1983peking11,
    author = "Rukang, W. and Shenlong, L",
    title = "Peking Man",
    year = "1983",
    howpublished = "Scientific American, v. 248, p. 86-94",
    note = "talkorigins\_source = {true}; raw\_reference = {Rukang, W., and Shenlong, L., 1983, Peking Man: Scientific American, v. 248, p. 86-94.}"
}

@misc{zechun1983peking15,
    author = "Zechun, L",
    title = "Peking Man's cave yeilds new finds",
    year = "1983",
    howpublished = "The Geographical Magazine, v. 55, no. 6, p. 297-300",
    note = "talkorigins\_source = {true}; raw\_reference = {Zechun, L., 1983, Peking Man's cave yeilds new finds: The Geographical Magazine, v. 55, no. 6, p. 297-300.}"
}

@misc{dong1984a2,
    author = "Dong, Z",
    title = "A new theropod dinosaur from the Middle Jurassic of Sichuan Basin",
    year = "1984",
    howpublished = "Vertebrate Palasiatica, v. XXII, p. 213-218; In Chinese",
    note = "talkorigins\_source = {true}; raw\_reference = {Dong, Z., 1984, A new theropod dinosaur from the Middle Jurassic of Sichuan Basin: Vertebrate Palasiatica, v. XXII, p. 213-218; In Chinese.}"
}

@misc{hou1984a6,
    author = "Hou, L. and Zhicheng, L",
    title = "A new fossil bird from the Lower Cretaceous of Gansu, and the early evolution of birds",
    year = "1984",
    howpublished = "Sci. Sinica B, v. XXVII, p. 1296- 1302",
    note = "talkorigins\_source = {true}; raw\_reference = {Hou, L., and Zhicheng, L., 1984, A new fossil bird from the Lower Cretaceous of Gansu, and the early evolution of birds: Sci. Sinica B, v. XXVII, p. 1296- 1302.}"
}

@misc{dong1985a4,
    author = "Dong, Z. and Tang, Z",
    title = "A new mid-Jurassic theropod (Gasosaurus constructus gen. et sp. nov.) from Dashanpu, Zigong, Sichuan Province, China",
    year = "1985",
    howpublished = "Vertebrate Palasiatica, v. XXIII, p. 77-83; In Chinese",
    note = "talkorigins\_source = {true}; raw\_reference = {Dong, Z., and Tang, Z., 1985, A new mid-Jurassic theropod (Gasosaurus constructus gen. et sp. nov.) from Dashanpu, Zigong, Sichuan Province, China: Vertebrate Palasiatica, v. XXIII, p. 77-83; In Chinese.}"
}

@misc{zhangwentang1985preliminary16,
    author = "Zhang Wen-tang, Hou Xian-guang",
    title = "Preliminary notes on the occurance of the unusual trilobite Naraoia in Asia [in Chinese]",
    year = "1985",
    howpublished = "Acta Palaeontologica Sinica, v. 24, p. 591-595",
    note = "talkorigins\_source = {true}; raw\_reference = {Zhang Wen-tang, and Hou Xian-guang, 1985, Preliminary notes on the occurance of the unusual trilobite Naraoia in Asia [in Chinese]: Acta Palaeontologica Sinica, v. 24, p. 591-595.}"
}

@misc{sunweiguo1987early12,
    author = "Sun Wei-guo, Hou Xian-guang",
    title = "Early Cambrian medusae from Chengjiang, Yunnan, China [in Chinese]",
    year = "1987",
    howpublished = "Acta Palaeontologica Sinica, v. 26, p. 257-270",
    note = "talkorigins\_source = {true}; raw\_reference = {Sun Wei-guo, and Hou Xian-guang, 1987, Early Cambrian medusae from Chengjiang, Yunnan, China [in Chinese]: Acta Palaeontologica Sinica, v. 26, p. 257-270.}"
}

@misc{sunweiguo1987early13,
    author = "Sun Wei-guo, Hou Xian-guang",
    title = "Early Cambrian worms from Chengjiang, Yunnan, China",
    year = "1987",
    howpublished = "Moatianshania Gen. Nov. [in Chinese]: Acta Palaeontologica Sinica, v. 26, p. 299-305",
    note = "talkorigins\_source = {true}; raw\_reference = {Sun Wei-guo, and Hou Xian-guang, 1987, Early Cambrian worms from Chengjiang, Yunnan, China: Moatianshania Gen. Nov. [in Chinese]: Acta Palaeontologica Sinica, v. 26, p. 299-305.}"
}

@misc{xianguang1987early9,
    author = "Xian-guang, Hou",
    title = "Early Cambrian large bivalved arthropods from Chengjiang, Eastern Yunnan [in Chinese]",
    year = "1987",
    howpublished = "Acta Palaeontologica Sinica, v. 26, p. 286-298",
    note = "talkorigins\_source = {true}; raw\_reference = {Hou Xian-guang, 1987, Early Cambrian large bivalved arthropods from Chengjiang, Eastern Yunnan [in Chinese]: Acta Palaeontologica Sinica, v. 26, p. 286-298.}"
}

@misc{xianguang1987three8,
    author = "Xian-guang, Hou",
    title = "Three new large arthropods from Lower Cambrian, Chengjiang, Eastern Yunnan [in Chinese]",
    year = "1987",
    howpublished = "Acta Palaeontologica Sinica, v. 26, p. 272-285",
    note = "talkorigins\_source = {true}; raw\_reference = {Hou Xian-guang, 1987, Three new large arthropods from Lower Cambrian, Chengjiang, Eastern Yunnan [in Chinese]: Acta Palaeontologica Sinica, v. 26, p. 272-285.}"
}

@misc{xianguang1987two7,
    author = "Xian-guang, Hou",
    title = "Two new arthropods from Lower Cambrian, Chengjiang, Eastern Yunnan [in Chinese]",
    year = "1987",
    howpublished = "Acta Palaeontologica Sinica, v. 26, p. 236- 256",
    note = "talkorigins\_source = {true}; raw\_reference = {Hou Xian-guang, 1987, Two new arthropods from Lower Cambrian, Chengjiang, Eastern Yunnan [in Chinese]: Acta Palaeontologica Sinica, v. 26, p. 236- 256.}"
}

@misc{houxianguang1988discovery10,
    author = "Hou Xian-guang, Sun Wei-guo",
    title = "Discovery of Chengjiang fauna at Meishucun, Jinning, Yunnan [in Chinese]",
    year = "1988",
    howpublished = "Acta Palaeontologica Sinica, v. 27, p. 1-12",
    note = "talkorigins\_source = {true}; raw\_reference = {Hou Xian-guang, and Sun Wei-guo, 1988, Discovery of Chengjiang fauna at Meishucun, Jinning, Yunnan [in Chinese]: Acta Palaeontologica Sinica, v. 27, p. 1-12.}"
}

The skeletal fossils of the Early Cambrian Meishucunian Stage from two key localities (Meishucun, Jinning County, and Xianfeng, Xundian County) in eastern Yunnan Province, China, are described and illustrated in detail to provide a basis for improved palaeobiological and biostratigraphical work. About 1250 new SEM illustrations (including a large number of stereo-pairs) of well-preserved material are presented. The taxonomy is extensively revised. When biological and preservational variability are taken into account, the number of genera and species may be reduced through synonymy to about one third of that reported in the literature. Thirty-eight genera (2 of which are new) and 57 species (5 of which are new) are described. The biology and affinities of many of these taxa are also diseussed, but excursions into suprageneric taxonomy are generally restrained. The Meishucunian biotas of Yunnan consist of three successive assemblages with very few taxa in common. The first, the Anabarites-Protohertzina-Arthrochites Assemblage, is dominated by Anabarites and other sedentary tube-dwelling organisms, but non-sedentary benthic mollusc-like fossils (Canopoconus) and probable predators (Protohertzina) also occur. The key elements of this fauna have a wide geographical distribution and may be compared with the earliest skeietal faunas on the Siberian Platform, the Canadian Cordillera, and other regions. The second, the Siphogonuchites-Paragloborilus Assemblage, is characterized by a great diversity of vagile mollusc-like and multisclerite-bearing animals, but also sedentary tube-dwellers and some possible predators (Cyrtochitesand Yunnanodus) occur. This fauna is largely endemic. The third, the Lapworthella-Tannuolina-Sinosachites Assemblage, is mainly characterized by widely distributed taxa of multisclerite-bearing animals (chancelloriids, Halkieria, Tannuolina, and Lapworthella). It has elements in common with late Atdabanian faunas in other regions of the world.

@book{doi101826182003741571989,
    author = "Qian, Yi and Bengtson, Stefan",
    title = "Palaeontology and biostratigraphy of the Early Cambrian Meishucunian Stage in Yunnan Province, South China",
    year = "1989",
    booktitle = "Fossils and strata",
    abstract = "The skeletal fossils of the Early Cambrian Meishucunian Stage from two key localities (Meishucun, Jinning County, and Xianfeng, Xundian County) in eastern Yunnan Province, China, are described and illustrated in detail to provide a basis for improved palaeobiological and biostratigraphical work. About 1250 new SEM illustrations (including a large number of stereo-pairs) of well-preserved material are presented. The taxonomy is extensively revised. When biological and preservational variability are taken into account, the number of genera and species may be reduced through synonymy to about one third of that reported in the literature. Thirty-eight genera (2 of which are new) and 57 species (5 of which are new) are described. The biology and affinities of many of these taxa are also diseussed, but excursions into suprageneric taxonomy are generally restrained. The Meishucunian biotas of Yunnan consist of three successive assemblages with very few taxa in common. The first, the Anabarites-Protohertzina-Arthrochites Assemblage, is dominated by Anabarites and other sedentary tube-dwelling organisms, but non-sedentary benthic mollusc-like fossils (Canopoconus) and probable predators (Protohertzina) also occur. The key elements of this fauna have a wide geographical distribution and may be compared with the earliest skeietal faunas on the Siberian Platform, the Canadian Cordillera, and other regions. The second, the Siphogonuchites-Paragloborilus Assemblage, is characterized by a great diversity of vagile mollusc-like and multisclerite-bearing animals, but also sedentary tube-dwellers and some possible predators (Cyrtochitesand Yunnanodus) occur. This fauna is largely endemic. The third, the Lapworthella-Tannuolina-Sinosachites Assemblage, is mainly characterized by widely distributed taxa of multisclerite-bearing animals (chancelloriids, Halkieria, Tannuolina, and Lapworthella). It has elements in common with late Atdabanian faunas in other regions of the world.",
    url = "https://doi.org/10.18261/8200374157-1989",
    doi = "10.18261/8200374157-1989",
    openalex = "W2409548894",
    references = "bengtson1976the, brasier1987microfossils, cloud1979earliest, doi101017s0016756800015922, doi101017s0016756800028296, doi10108003115517608619064, doi10108011035898809452656, doi101098rstb19850005, doi101111j150239311975tb01311x, doi101111j150239311981tb01104x, doi101111j150239311983tb01993x, doi101111j150239311986tb00741x, doi101126science581501269, doi101130spe196p43, doi101139e83050, doi101144gsjgs13130289, doi10182618200067378198301, doi1018814epiiugs1985v8i2003, morris1980shelly, openalexw1549886310, openalexw2598873191"
}

The Lower Cambrian Chengjiang fauna is reviewed and shown to be closely comparable with the younger Burgess Shale fauna. but with various differences in detail. A diverse group of more or less annulated lobopod animals including ‘armoured lobopods’ are regarded as representatives of the phylum Onychophora. ‘Trilobitomorphs’ include several new types. Probable protaspides of the trilobitomorph Naraoia are described. No molluses or deuterostomes have been identified. The preservational orientations of the various taxa are reviewed and compared with orientations of the Burgess Shale taxa. Orientation in the sediment is found to be closely correlated to the original shape of individuals. Several new genera and species are described: the segmented. worm‐shaped Yunnanozoon lividum gen. et sp.n., the ‘armoured lobopods’ Onychodictyon ferox gen. et sp.n. and Cardiodictyon catenulum gen. et sp.n. and the arthropods Saperion glumaceum gen. et sp.n., Sinoburius Iunaris gen. et sp.n., and Xandarella spectaculum gen. et sp.n.

@article{doi101111j146364091991tb00303x,
    author = "XIANGUANG, HOU and Ramsköld, Lars and Bergström, Jan",
    title = "Composition and preservation of the Chengjiang fauna –a Lower Cambrian soft‐bodied biota",
    year = "1991",
    journal = "Zoologica Scripta",
    abstract = "The Lower Cambrian Chengjiang fauna is reviewed and shown to be closely comparable with the younger Burgess Shale fauna. but with various differences in detail. A diverse group of more or less annulated lobopod animals including ‘armoured lobopods’ are regarded as representatives of the phylum Onychophora. ‘Trilobitomorphs’ include several new types. Probable protaspides of the trilobitomorph Naraoia are described. No molluses or deuterostomes have been identified. The preservational orientations of the various taxa are reviewed and compared with orientations of the Burgess Shale taxa. Orientation in the sediment is found to be closely correlated to the original shape of individuals. Several new genera and species are described: the segmented. worm‐shaped Yunnanozoon lividum gen. et sp.n., the ‘armoured lobopods’ Onychodictyon ferox gen. et sp.n. and Cardiodictyon catenulum gen. et sp.n. and the arthropods Saperion glumaceum gen. et sp.n., Sinoburius Iunaris gen. et sp.n., and Xandarella spectaculum gen. et sp.n.",
    url = "https://doi.org/10.1111/j.1463-6409.1991.tb00303.x",
    doi = "10.1111/j.1463-6409.1991.tb00303.x",
    openalex = "W2088299548",
    references = "doi101017s0094837300009994, doi101038326181a0, doi101098rstb19810007, doi101111j1469185x1984tb00411x, doi101111j150239311989tb01332x, doi101126science2464928339, doi101826182003741571989, doi1023072992562, doi104095103962, doi105860choice284524, openalexw2138270429, openalexw2240758963, openalexw2754161204"
}

1. Origin of metazoans: a phylogeny deducted from sequences of the 28S ribosomal RNA R. Christen, A. Ratto, A. Baroin, R. Persasso, K. Grell and A. Adoutte 2. Major factors in the rapidity and extent of the metazoan radiation during the Proterozoic-Phanerozoic transition J. W. Valentine 3. Divergence and persistence of highly ranked taxa R. R. Strathmann 4. Problematical taxa: a problem for biology or biologists? S. Conway Morris 5. Metazoan evolution around the Precambrian-Cambrian transition J. Bergstroem 6. Cladistic analysis of metazoan phyla and the placement of fossil problematica F. R. Schram 7. Is fossil evidence consistent with traditional views of the early metazoan phylogeny? J. Dzik 8. Lower Cambrian lagerstatte from Chengjiang, Yunnan, China: insights for reconstructing early Metazoan life Chen Jun-Yuan and D. D. Erdtmann 9. Middle Cambrian biotic diversity: examples from four Utah Lagerstatten L. A. Robison 10. Extant 'problematica' within or near the Metazoa G. Haszprunar, R. M. Riefer and P. Schuchert 11. On the origin of the Bilateria: traditional views and recent altneratuve concepts R. M. Rieger, G. Hazprunar and P. Schuchert 12. Problematic reef-building spongers R. A. Wood 13. Beach and laboratory experiments with the jellyfish Aurelia, and remarks on some fossil 'medusoid' traces D. L. Bruton 14. Early Cambrian medusiform fossils from Chengjiang, Yannan, China Sun Weiguo 15. The enigma of conulariid affinities L. E. Babcock 16. Evolutionary affinities of conulariids H. Van Iten 17. Functional morphology of the Class Helcionelloida nov., and the early evolution of the Molusca J. S. Peel 18. The arthropods of the Lower Cambrian Chengjiang fauna, with relationships and evolutionary significance Hou Xian-Guang and J. Bergstroem 16. Early Palaeozoic arthropods and problems of arthropod phylogeny with some notes on taxa of doubtful affinities A. M. Simonetta and L. Delle Cave 17. New observations on the thylacocephala (Arthropoda, Crustacea) A. Alessandrello, P. Arduini, G. Pinna and G. Teruzzi 18. Fossil Acarida: contribution of palaeontolgical data to acarid evolutionary history F. Bernini 19. Are Protura really insects R. Dallai 20. The Tully Monster and a new approach to analyzing problematica J. S. Beall 21. Problematica-incertae sedis E. L. Yochelson.

@book{openalexw645459046,
    author = "Simonetta, Alberto M. and Morris, Simon Conway",
    title = "The Early evolution of Metazoa and the significance of problematic taxa: proceedings of an international symposium held at the University of Camerino, 27-31 March 1989",
    year = "1991",
    abstract = "1. Origin of metazoans: a phylogeny deducted from sequences of the 28S ribosomal RNA R. Christen, A. Ratto, A. Baroin, R. Persasso, K. Grell and A. Adoutte 2. Major factors in the rapidity and extent of the metazoan radiation during the Proterozoic-Phanerozoic transition J. W. Valentine 3. Divergence and persistence of highly ranked taxa R. R. Strathmann 4. Problematical taxa: a problem for biology or biologists? S. Conway Morris 5. Metazoan evolution around the Precambrian-Cambrian transition J. Bergstroem 6. Cladistic analysis of metazoan phyla and the placement of fossil problematica F. R. Schram 7. Is fossil evidence consistent with traditional views of the early metazoan phylogeny? J. Dzik 8. Lower Cambrian lagerstatte from Chengjiang, Yunnan, China: insights for reconstructing early Metazoan life Chen Jun-Yuan and D. D. Erdtmann 9. Middle Cambrian biotic diversity: examples from four Utah Lagerstatten L. A. Robison 10. Extant 'problematica' within or near the Metazoa G. Haszprunar, R. M. Riefer and P. Schuchert 11. On the origin of the Bilateria: traditional views and recent altneratuve concepts R. M. Rieger, G. Hazprunar and P. Schuchert 12. Problematic reef-building spongers R. A. Wood 13. Beach and laboratory experiments with the jellyfish Aurelia, and remarks on some fossil 'medusoid' traces D. L. Bruton 14. Early Cambrian medusiform fossils from Chengjiang, Yannan, China Sun Weiguo 15. The enigma of conulariid affinities L. E. Babcock 16. Evolutionary affinities of conulariids H. Van Iten 17. Functional morphology of the Class Helcionelloida nov., and the early evolution of the Molusca J. S. Peel 18. The arthropods of the Lower Cambrian Chengjiang fauna, with relationships and evolutionary significance Hou Xian-Guang and J. Bergstroem 16. Early Palaeozoic arthropods and problems of arthropod phylogeny with some notes on taxa of doubtful affinities A. M. Simonetta and L. Delle Cave 17. New observations on the thylacocephala (Arthropoda, Crustacea) A. Alessandrello, P. Arduini, G. Pinna and G. Teruzzi 18. Fossil Acarida: contribution of palaeontolgical data to acarid evolutionary history F. Bernini 19. Are Protura really insects R. Dallai 20. The Tully Monster and a new approach to analyzing problematica J. S. Beall 21. Problematica-incertae sedis E. L. Yochelson.",
    url = "https://openalex.org/W645459046",
    openalex = "W645459046"
}

Disparity is a measure of the range or significance of morphology in a given sample of organisms, as opposed to diversity, which is expressed in terms of the number (and sometimes ranking) of taxa. At present there is no agreed definition of disparity, much less any consensus on how to measure it. Two possible categories of metric are considered here, one independent of any hypothesis of relationship (phenetics), the other constrained within an evolutionary framework (cladistics). The Early Cambrian radiation was clearly a period of significant morphologic and taxonomic diversification. However, we question the interpretation of its first generation products as numerous body plans at the highest level. Four phenetic and two cladistic measures have been used to compare disparity among Cambrian arthropods with that in the living fauna. Phenetic methods assessing character-state variability and the amount of morphological attribute space occupied yield similar results for Cambrian and Recent arthropods. Assessments of disparity within a taxonomic framework rely on the identification of particular characters that delineate higher level body plans. This requires a phylogenetic interpretation, a cladistic investigation of hierarchical structure in the data. Both sets of arthropods fall within the same major clades, and within this cladistic framework the amount of character-state evolution in the two groups is comparable. None of these methods identifies markedly greater disparity among the Cambrian compared with the Recent taxa. Although measures of disparity are applied here to a consideration of the Cambrian radiation, the metrics clearly have a much wider potential for estimating macroevolutionary trends independently from existing taxonomic frameworks. Geometric morphometry is ideal for measuring morphological variety at lower taxonomic levels, but it requires the recognition of homologous landmarks in all the forms under comparison, or the identification of entire homologous structures. Conventional phenetics has much wider application as it can operate on data coded as discrete homologous character states (this facility is also a requirement of cladistics), which are a more appropriate basis for comparing disparity in markedly dissimilar forms.

@article{doi101017s009483730001263x,
    author = "Wills, Matthew A. and Briggs, Derek E. G. and Fortey, Richard A.",
    title = "Disparity as an evolutionary index: a comparison of Cambrian and Recent arthropods",
    year = "1994",
    journal = "Paleobiology",
    abstract = "Disparity is a measure of the range or significance of morphology in a given sample of organisms, as opposed to diversity, which is expressed in terms of the number (and sometimes ranking) of taxa. At present there is no agreed definition of disparity, much less any consensus on how to measure it. Two possible categories of metric are considered here, one independent of any hypothesis of relationship (phenetics), the other constrained within an evolutionary framework (cladistics). The Early Cambrian radiation was clearly a period of significant morphologic and taxonomic diversification. However, we question the interpretation of its first generation products as numerous body plans at the highest level. Four phenetic and two cladistic measures have been used to compare disparity among Cambrian arthropods with that in the living fauna. Phenetic methods assessing character-state variability and the amount of morphological attribute space occupied yield similar results for Cambrian and Recent arthropods. Assessments of disparity within a taxonomic framework rely on the identification of particular characters that delineate higher level body plans. This requires a phylogenetic interpretation, a cladistic investigation of hierarchical structure in the data. Both sets of arthropods fall within the same major clades, and within this cladistic framework the amount of character-state evolution in the two groups is comparable. None of these methods identifies markedly greater disparity among the Cambrian compared with the Recent taxa. Although measures of disparity are applied here to a consideration of the Cambrian radiation, the metrics clearly have a much wider potential for estimating macroevolutionary trends independently from existing taxonomic frameworks. Geometric morphometry is ideal for measuring morphological variety at lower taxonomic levels, but it requires the recognition of homologous landmarks in all the forms under comparison, or the identification of entire homologous structures. Conventional phenetics has much wider application as it can operate on data coded as discrete homologous character states (this facility is also a requirement of cladistics), which are a more appropriate basis for comparing disparity in markedly dissimilar forms.",
    url = "https://doi.org/10.1017/s009483730001263x",
    doi = "10.1017/s009483730001263x",
    openalex = "W2131955742",
    references = "crossref1977chapter, doi101007bf02289565, doi101007bf02289630, doi101007bf02289694, doi101017s0094837300015864, doi101093biomet5334325, doi101098rstb19810007, doi101098rstb19830020, doi101098rstb19850005, doi101111j155856461982tb05453x, doi10113719781611970319, doi101144gsjgs14940631, doi1023072288218, doi1023072346439, doi103133ofr81743, doi105281zenodo16435756, doi105860choice273873, openalexw2754161204, openalexw2944885317"
}

The Chinese Early Cambrian Chengjiang fauna includes three different anomalocaridids, a globally spread, extinct marine group including the largest known Cambrian animals. Anomalocaridids were active predators, and their presence implies that a complex ecosystem appeared abruptly in the earliest Phanerozoic. Complete specimens display several sets of characters shared only with some other exclusively Cambrian forms. This evidence indicates that anomalocaridids, Opabinia, and Kerygmachela form a monophyletic clade. Certain features indicate arthropod affinities of the lade, and for this group an unnamed (sub)phylum-level taxon within an arthropod (super)phylum is proposed.

@article{doi101126science26451631304,
    author = "Chen, Junyuan and Ramsköld, Lars and Zhou, Gui-qing",
    title = "Evidence for Monophyly and Arthropod Affinity of Cambrian Giant Predators",
    year = "1994",
    journal = "Science",
    abstract = "The Chinese Early Cambrian Chengjiang fauna includes three different anomalocaridids, a globally spread, extinct marine group including the largest known Cambrian animals. Anomalocaridids were active predators, and their presence implies that a complex ecosystem appeared abruptly in the earliest Phanerozoic. Complete specimens display several sets of characters shared only with some other exclusively Cambrian forms. This evidence indicates that anomalocaridids, Opabinia, and Kerygmachela form a monophyletic clade. Certain features indicate arthropod affinities of the lade, and for this group an unnamed (sub)phylum-level taxon within an arthropod (super)phylum is proposed.",
    url = "https://doi.org/10.1126/science.264.5163.1304",
    doi = "10.1126/science.264.5163.1304",
    openalex = "W2057320315"
}

Abstract Five anomalocaridids are described from the Lower Cambrian Chengjiang fauna of China: Anomalocaris saron sp.n., Anomalocaris sp., Amplectobelua symbrachiata gen. et sp.n., Cucumericrus decoratus gen. et sp.n., and Parapeytoia yunnanensis gen. et sp.n. Ventral trunk appendages are reported for the first time. In C. decoratus and P. yunnanensis, each appendage has a distal segmented walking leg, and a wide lateral extension of a long proximal portion forms the structure previously described as a lateral fin. Furthermore, the structure of the dorsum is elucidated. The supposed ventrolateral gills are flat scales covering the back in transverse rows. The mouth was directed backwards, as in the Middle Cambrian Opabinia regalis, and not directed ventrally as in previous reconstructions. The radial arrangement of the circum‐oral sclerites suggests that anomalocaridids were related to aschelminth worms rather than to arthropods. Hou, X.‐g., Bergström, J. & Ahlberg, P., 1995: Anomalocaris and other large animals in the Lower Cambrian Chengjiang fauna of southwest China. GFF, Vol. 117 (Pt. 3, September), pp. 163–183. Stockholm. ISSN 1103–5897.

@article{doi10108011035899509546213,
    author = "Hou, Xianguang and Bergström, Jan and Ahlberg, Per",
    title = "Anomalocaris and other large animals in the lower Cambrian Chengjiang fauna of southwest China",
    year = "1995",
    journal = "GFF",
    abstract = "Abstract Five anomalocaridids are described from the Lower Cambrian Chengjiang fauna of China: Anomalocaris saron sp.n., Anomalocaris sp., Amplectobelua symbrachiata gen. et sp.n., Cucumericrus decoratus gen. et sp.n., and Parapeytoia yunnanensis gen. et sp.n. Ventral trunk appendages are reported for the first time. In C. decoratus and P. yunnanensis, each appendage has a distal segmented walking leg, and a wide lateral extension of a long proximal portion forms the structure previously described as a lateral fin. Furthermore, the structure of the dorsum is elucidated. The supposed ventrolateral gills are flat scales covering the back in transverse rows. The mouth was directed backwards, as in the Middle Cambrian Opabinia regalis, and not directed ventrally as in previous reconstructions. The radial arrangement of the circum‐oral sclerites suggests that anomalocaridids were related to aschelminth worms rather than to arthropods. Hou, X.‐g., Bergström, J. \& Ahlberg, P., 1995: Anomalocaris and other large animals in the Lower Cambrian Chengjiang fauna of southwest China. GFF, Vol. 117 (Pt. 3, September), pp. 163–183. Stockholm. ISSN 1103–5897.",
    url = "https://doi.org/10.1080/11035899509546213",
    doi = "10.1080/11035899509546213",
    openalex = "W1992001335",
    references = "doi101017s0022336000032145, doi101038114085a0, doi101038337695c0, doi10108003115519608619475, doi101098rstb19810164, doi101098rstb19850096, doi101111j146364091991tb00303x, doi101126science26451631304, doi1023072992562, openalexw3127114020"
}

Abstract Articulated halkieriids of Halkieria evangelista sp. nov. are described from the Sirius Passet fauna in the Lower Cambrian Buen Formation of Peary Land, North Greenland. Three zones of sclerites are recognizable: obliquely inclined rows of dorsal palmates, quincuncially inserted lateral cultrates and imbricated bundles of ventro-lateral siculates. In addition there is a prominent shell at both ends, each with radial ornamentation. Both sclerites and shells were probably calcareous, but increase in body size led to insertion of additional sclerites but marginal accretion of the shells. The ventral sole was soft and, in life, presumably muscular. Recognizable features of internal anatomy include a gut trace and possible musculature, inferred from imprints on the interior of the anterior shell. Halkieriids are closely related to the Middle Cambrian Wixaxia, best known from the Burgess Shale: this clade appears to have played an important role in early protostome evolution. From an animal fairly closely related to Wixaxia arose the polychaete annelids; the bundles of siculate sclerites prefigure the neurochaetae whereas the dorsal notochaetae derive from the palmates. Wixaxia appears to have a relic shell and a similar structure in the sternaspid polychaetes may be an evolutionary remnant. The primitive state in extant polychaetes is best expressed in groups such as chrysopetalids, aphroditaceans and amphinomids. The homology between polychaete chaetae and the mantle setae of brachiopods is one line of evidence to suggest that the latter phylum arose from a juvenile halkieriid in which the posterior shell was first in juxtaposition to the anterior and rotated beneath it to provide the bivalved condition of an ancestral brachiopod. H. evangelista sp. nov. has shells which resemble those of a brachiopod; in particular the posterior one. From predecessors of the halkieriids known as siphogonuchitids it is possible that both chitons (polyplacophorans) and conchiferan molluscs arose. The hypothesis of halkieriids and their relatives having a key role in annelid—brachiopod—mollusc evolution is in accord with some earlier proposals and recent evidence from molecular biology. It casts doubt, however, on a number of favoured concepts including the primitive annelid being oligochaetoid and a burrower, the brachiopods being deuterostomes and the coelom being an archaic feature of metazoans. Rather, the annelid coelom arose as a functional consequence of the transition from a creeping halkieriid to a polychaete with stepping parapodial locomotion.

@article{doi101098rstb19950029,
    author = "Morris, Simon Conway and Peel, John S.",
    title = "Articulated halkieriids from the Lower Cambrian of North Greenland and their role in early protostome evolution",
    year = "1995",
    journal = "Philosophical Transactions of the Royal Society B Biological Sciences",
    abstract = "Abstract Articulated halkieriids of Halkieria evangelista sp. nov. are described from the Sirius Passet fauna in the Lower Cambrian Buen Formation of Peary Land, North Greenland. Three zones of sclerites are recognizable: obliquely inclined rows of dorsal palmates, quincuncially inserted lateral cultrates and imbricated bundles of ventro-lateral siculates. In addition there is a prominent shell at both ends, each with radial ornamentation. Both sclerites and shells were probably calcareous, but increase in body size led to insertion of additional sclerites but marginal accretion of the shells. The ventral sole was soft and, in life, presumably muscular. Recognizable features of internal anatomy include a gut trace and possible musculature, inferred from imprints on the interior of the anterior shell. Halkieriids are closely related to the Middle Cambrian Wixaxia, best known from the Burgess Shale: this clade appears to have played an important role in early protostome evolution. From an animal fairly closely related to Wixaxia arose the polychaete annelids; the bundles of siculate sclerites prefigure the neurochaetae whereas the dorsal notochaetae derive from the palmates. Wixaxia appears to have a relic shell and a similar structure in the sternaspid polychaetes may be an evolutionary remnant. The primitive state in extant polychaetes is best expressed in groups such as chrysopetalids, aphroditaceans and amphinomids. The homology between polychaete chaetae and the mantle setae of brachiopods is one line of evidence to suggest that the latter phylum arose from a juvenile halkieriid in which the posterior shell was first in juxtaposition to the anterior and rotated beneath it to provide the bivalved condition of an ancestral brachiopod. H. evangelista sp. nov. has shells which resemble those of a brachiopod; in particular the posterior one. From predecessors of the halkieriids known as siphogonuchitids it is possible that both chitons (polyplacophorans) and conchiferan molluscs arose. The hypothesis of halkieriids and their relatives having a key role in annelid—brachiopod—mollusc evolution is in accord with some earlier proposals and recent evidence from molecular biology. It casts doubt, however, on a number of favoured concepts including the primitive annelid being oligochaetoid and a burrower, the brachiopods being deuterostomes and the coelom being an archaic feature of metazoans. Rather, the annelid coelom arose as a functional consequence of the transition from a creeping halkieriid to a polychaete with stepping parapodial locomotion.",
    url = "https://doi.org/10.1098/rstb.1995.0029",
    doi = "10.1098/rstb.1995.0029",
    openalex = "W2001586405",
    references = "doi101007978148992427812, doi1010160301926885900518, doi101017s0022336000037057, doi101038326181a0, doi101038345802a0, doi101038361219a0, doi101098rstb19790006, doi101098rstb19850005, doi101111j143904691975tb00509x, doi101111j146363951991tb00312x, doi101111j146364091991tb00303x, doi101111j150239311969tb01258x, doi101111j150239311993tb01502x, doi101126science2224620163, doi101126science2464928339, doi101126science3277277, doi101144gsjgs14940631, doi101146annureves10110179001551, doi105962bhltitle8596, morris1979the, morris1987a, openalexw2138270429, openalexw2302261279, openalexw2754161204, openalexw589153876"
}

@book{doi101826182003769311997,
    author = "Xianguang, Hou and Strom, Jan Berg",
    title = "Arthropods of the Lower Cambrian Chengjiang fauna, southwest China",
    year = "1997",
    booktitle = "Fossils and strata",
    url = "https://doi.org/10.18261/8200376931-1997",
    doi = "10.18261/8200376931-1997",
    openalex = "W2417360735",
    references = "doi1010079783642809101, doi1010160012825280900641, doi101098rstb19780005, doi101098rstb19810007, doi101098rstb19810164, doi101098rstb19830020, doi101111j109636421995tb00110x, doi101111j146364091991tb00303x, doi101111j150239311990tb01373x, doi101126science25650641670, doi10182618200049639197506, doi10182618200374874199301, doi102307sysbio284635, doi104095103458, doi104095103962, doi105860choice273873, doi105860choice284524, dzik1988the, müller1983crustacea, openalexw2240758963, openalexw2886616075"
}

Three additional arthropods from the Early Cambrian Chengjiang Fauna, Yunnan, South-West China

@article{openalexw650377807,
    author = "Xianguang, Bergström Hou",
    title = "Three additional arthropods from the Early Cambrian Chengjiang Fauna, Yunnan, South-West China",
    year = "1998",
    abstract = "Three additional arthropods from the Early Cambrian Chengjiang Fauna, Yunnan, South-West China",
    url = "https://openalex.org/W650377807",
    openalex = "W650377807"
}

Five new bivalved arthropods are described from the Lower Cambrian Chengjiang fauna, Yunnan, China. All of them are rare in the fauna, represented by one or two individuals among thousands of specimens. Four of the five new taxa are preserved with soft parts that show a clear distinction between them. The new taxa provide new important information concerning the soft bodied and limb characters of the early bivalved arthropods. A significant lesson is that, not knowing any soft parts, it is virtually impossible to place systematically a new type of bivalved carapace. It is often impossible even to tell if it is a crustacean or not. A second antenna in the shape of a “great appendage” is identified for the first time among the bivalved arthropods. The new taxa include representatives of the order Pectocaridida, the families Pectocarididae, Clypecarididae and Occacarididae, the genera and species Pectocaris spatiosa, Clypecaris pteroidea, Occacaris oviformis, Forfexicaris valida and Yunnanocaris megista.

@article{doi101017s002233600002758x,
    author = "Hou, Xianguang",
    title = "New rare bivalved arthropods from the Lower Cambrian Chengjiang fauna, Yunnan, China",
    year = "1999",
    journal = "Journal of Paleontology",
    abstract = "Five new bivalved arthropods are described from the Lower Cambrian Chengjiang fauna, Yunnan, China. All of them are rare in the fauna, represented by one or two individuals among thousands of specimens. Four of the five new taxa are preserved with soft parts that show a clear distinction between them. The new taxa provide new important information concerning the soft bodied and limb characters of the early bivalved arthropods. A significant lesson is that, not knowing any soft parts, it is virtually impossible to place systematically a new type of bivalved carapace. It is often impossible even to tell if it is a crustacean or not. A second antenna in the shape of a “great appendage” is identified for the first time among the bivalved arthropods. The new taxa include representatives of the order Pectocaridida, the families Pectocarididae, Clypecarididae and Occacarididae, the genera and species Pectocaris spatiosa, Clypecaris pteroidea, Occacaris oviformis, Forfexicaris valida and Yunnanocaris megista.",
    url = "https://doi.org/10.1017/s002233600002758x",
    doi = "10.1017/s002233600002758x",
    openalex = "W2341789411",
    references = "doi101016003101829390065q, doi10108011035899509546213, doi101098rstb19780005, doi101098rstb19810007, doi101111j146364091991tb00303x, doi101111j150239311990tb01373x, doi101826182003769311997, doi1023072992562, openalexw2205767785"
}

An updated reconstruction of the body plan, functional anatomy and life attitude of the bradoriid arthropod Kunmingella is proposed, based on new fossil specimens with preserved soft parts found in the lower Cambrian of Chengjiang and Haikou (Yunnan, SW China) and on previous evidence. The animal has a single pair of short antennae pointing towards the front (a setal pattern indicates a possible sensory function). The following set of seven appendages (each composed of a 5-segmented endopod and a leaf-like exopod fringed with setae) is poorly differentiated, except the first three pairs (with possible rake-like endopodial outgrowths, smaller exopods) and the last pair of appendages (endopod with longer and more slender podomeres). The endopods are interpreted as walking legs with a possible role in handling food particles (marginal outgrowth with setae). The leaf-like exopods may have had a respiratory function. The trunk end is short, pointed, flanked with furcal-like rami and projects beyond the posterior margin of the carapace. The attachment of the body to the exoskeleton is probably cephalic and apparently lacks any well-developed adductor muscle system. The inferred life attitude of Kunmingella (e.g. crawling on the surface of the sediment) was that of a dorsoventrally flattened arthropod capped by a folded dorsal shield (ventral gape at least 120°), thus resembling the living ostracode Manawa. The animal was also probably able to close its carapace as a response to environmental stress or to survive unfavourable conditions (e.g. buried in sediment). The anterior lobes of the valves are likely to have accommodated visual organs (possibly lensless receptors perceiving ambient light through the translucent head shield). Preserved eggs or embryos suggest a possible ventral brood care. The presence of Kunmingella in coprolites and its numerical abundance in Chengjiang sediment indicate that bradoriids constituted an important source of food for larger predators. Kunmingella differs markedly from the representatives of the crown group Crustacea (extant and Cambrian taxa) and from the stem group derivatives of Crustacea (exemplified by phosphatocopids and some ‘Orsten’ taxa) in showing no major sign of limb specialization (e.g. related to feeding strategies). Although it resembles other Chengjiang euarthropods in important aspects of its body plan (e.g. uniramous antennae, endopod/exopod configuration), Kunmingella possesses several features (e.g. antennal morphology, post-antennular appendages with 5-segmented endopods) which support the view that bradoriids may be very early derivatives of the stem line Crustacea.

@article{doi101111j150239311999tb00547x,
    author = "Shu, Degan and Vannier, Jean and Luo, Huilin and Chen, Ling and Zhang, Xingliang and Hu, Shixue",
    title = "Anatomy and lifestyle of Kunmingella (Arthropoda, Bradoriida) from the Chengjiang fossil Lagerstätte (lower Cambrian; Southwest China)",
    year = "1999",
    journal = "Lethaia",
    abstract = "An updated reconstruction of the body plan, functional anatomy and life attitude of the bradoriid arthropod Kunmingella is proposed, based on new fossil specimens with preserved soft parts found in the lower Cambrian of Chengjiang and Haikou (Yunnan, SW China) and on previous evidence. The animal has a single pair of short antennae pointing towards the front (a setal pattern indicates a possible sensory function). The following set of seven appendages (each composed of a 5-segmented endopod and a leaf-like exopod fringed with setae) is poorly differentiated, except the first three pairs (with possible rake-like endopodial outgrowths, smaller exopods) and the last pair of appendages (endopod with longer and more slender podomeres). The endopods are interpreted as walking legs with a possible role in handling food particles (marginal outgrowth with setae). The leaf-like exopods may have had a respiratory function. The trunk end is short, pointed, flanked with furcal-like rami and projects beyond the posterior margin of the carapace. The attachment of the body to the exoskeleton is probably cephalic and apparently lacks any well-developed adductor muscle system. The inferred life attitude of Kunmingella (e.g. crawling on the surface of the sediment) was that of a dorsoventrally flattened arthropod capped by a folded dorsal shield (ventral gape at least 120°), thus resembling the living ostracode Manawa. The animal was also probably able to close its carapace as a response to environmental stress or to survive unfavourable conditions (e.g. buried in sediment). The anterior lobes of the valves are likely to have accommodated visual organs (possibly lensless receptors perceiving ambient light through the translucent head shield). Preserved eggs or embryos suggest a possible ventral brood care. The presence of Kunmingella in coprolites and its numerical abundance in Chengjiang sediment indicate that bradoriids constituted an important source of food for larger predators. Kunmingella differs markedly from the representatives of the crown group Crustacea (extant and Cambrian taxa) and from the stem group derivatives of Crustacea (exemplified by phosphatocopids and some ‘Orsten’ taxa) in showing no major sign of limb specialization (e.g. related to feeding strategies). Although it resembles other Chengjiang euarthropods in important aspects of its body plan (e.g. uniramous antennae, endopod/exopod configuration), Kunmingella possesses several features (e.g. antennal morphology, post-antennular appendages with 5-segmented endopods) which support the view that bradoriids may be very early derivatives of the stem line Crustacea.",
    url = "https://doi.org/10.1111/j.1502-3931.1999.tb00547.x",
    doi = "10.1111/j.1502-3931.1999.tb00547.x",
    openalex = "W1989069995",
    references = "briggs1994decay, doi101016003101827190040x, doi101017s002233600002758x, doi101098rstb19910094, doi101144gsjgs15061035, doi101163193724087x00054, doi101826182003741571989, doi101826182003769311997, doi1023073515467, doi105962bhltitle41372, openalexw2134978213, openalexw2754161204, xianguang1999new"
}

@incollection{openalexw2597139979,
    author = "Luo, Huilin and Hu, Shixue and Chen, Liangzhong and Shishan, Zhang and Tao, Yonghe.",
    title = "Early Cambrian Chengjiang fauna from Kunming region, China",
    year = "1999",
    booktitle = "Unknown eBooks",
    openalex = "W2597139979"
}

Five new bivalved arthropods are described from the Lower Cambrian Chengjiang fauna, Yunnan, China. All of them are rare in the fauna, represented by one or two individuals among thousands of specimens. Four of the five new taxa are preserved with soft parts that show a clear distinction between them. The new taxa provide new important information concerning the soft bodied and limb characters of the early bivalved arthropods. A significant lesson is that, not knowing any soft parts, it is virtually impossible to place systematically a new type of bivalved carapace. It is often impossible even to tell if it is a crustacean or not. A second antenna in the shape of a “great appendage” is identified for the first time among the bivalved arthropods. The new taxa include representatives of the order Pectocaridida, the families Pectocarididae, Clypecarididae and Occacarididae, the genera and species Pectocaris spatiosa, Clypecaris pteroidea, Occacaris oviformis, Forfexicaris valida and Yunnanocaris megista.

@article{xianguang1999new,
    author = "Xian-Guang, Hou",
    title = "New rare bivalved arthropods from the Lower Cambrian Chengjiang fauna, Yunnan, China",
    year = "1999",
    journal = "Journal of Paleontology",
    abstract = "Five new bivalved arthropods are described from the Lower Cambrian Chengjiang fauna, Yunnan, China. All of them are rare in the fauna, represented by one or two individuals among thousands of specimens. Four of the five new taxa are preserved with soft parts that show a clear distinction between them. The new taxa provide new important information concerning the soft bodied and limb characters of the early bivalved arthropods. A significant lesson is that, not knowing any soft parts, it is virtually impossible to place systematically a new type of bivalved carapace. It is often impossible even to tell if it is a crustacean or not. A second antenna in the shape of a “great appendage” is identified for the first time among the bivalved arthropods. The new taxa include representatives of the order Pectocaridida, the families Pectocarididae, Clypecarididae and Occacarididae, the genera and species Pectocaris spatiosa, Clypecaris pteroidea, Occacaris oviformis, Forfexicaris valida and Yunnanocaris megista.",
    url = "https://doi.org/10.1017/s002233600002758x",
    doi = "10.1017/s002233600002758x",
    number = "1",
    openalex = "W2341789411",
    pages = "102-116",
    volume = "73",
    references = "doi101016003101829390065q, doi10108011035899509546213, doi101098rstb19780005, doi101098rstb19810007, doi101111j146364091991tb00303x, doi101111j150239311990tb01373x, doi101826182003769311997, doi1023072992562, openalexw2205767785"
}

@article{doi10103835106514,
    author = "Shu, Degan and Morris, Simon Conway and Han, Jian and Chen, L. and Zhang, X.-L. and Zhang, Zhifei and Liu, H.-Q. and Li, Y. and Liu, J.-N.",
    title = "Primitive deuterostomes from the Chengjiang Lagerstätte (Lower Cambrian, China)",
    year = "2001",
    journal = "Nature",
    url = "https://doi.org/10.1038/35106514",
    doi = "10.1038/35106514",
    openalex = "W2073301242",
    references = "doi101038377720a0, doi101144jgs1582211, doi101826182003769311997"
}

@article{doi1011301052517320010110004tcbrot20co2,
    author = "Babcock, Loren E. and Wentang, Zhang and Leslie, Stephen A.",
    title = "The Chengjiang Biota: Record of the Early Cambrian Diversification of Life and Clues to Exceptional Preservation of Fossils",
    year = "2001",
    journal = "GSA Today",
    url = "https://doi.org/10.1130/1052-5173(2001)011<0004:tcbrot>2.0.co;2",
    doi = "10.1130/1052-5173(2001)011<0004:tcbrot>2.0.co;2",
    openalex = "W2075137781"
}

Soft-bodied and lightly sclerotized Chengjiang fossils have been found at more than ten new localities in the Lower Cambrian Qiongzhusi and Canglangpu formations of east central Yunnan. At the same time, three different fossil assemblages have been recognized, i.e. Kunmingella–Isoxys–Naraoia assemblage at Chengjiang, Kunmingella – Cricocosmia assemblage at Haikou, and Kunmingella – Wutingaspis – Obolus assemblage at Anning and Wuding. These sites yield new and striking specimens, such as a new tentacular animal, brachiopods with pedicles preserved, and the enigmatic Xidazoon (having mixed phyla characters), which are significant in our understanding of animal phylogeny. Above all, the appearance of diverse chordates and agnathans (vertebrates) greatly expands our knowledge of the Cambrian explosion. The discovery of soft-bodied fossils at many new localities and the very wide distribution of the Qiongzhusi Formation suggest that many more localities remain to be discovered. Here, a new early form of tentaculate, Cambrotentacus sanwuia gen. et sp. nov. (perhaps related to lophophorates and entoprocts), is described.

@article{doi101144jgs1582211,
    author = "Zhang, Xingliang and Shu, Degan and Li, Yong and Han, Jian",
    title = "New sites of Chengjiang fossils: crucial windows on the Cambrian explosion",
    year = "2001",
    journal = "Journal of the Geological Society",
    abstract = "Soft-bodied and lightly sclerotized Chengjiang fossils have been found at more than ten new localities in the Lower Cambrian Qiongzhusi and Canglangpu formations of east central Yunnan. At the same time, three different fossil assemblages have been recognized, i.e. Kunmingella–Isoxys–Naraoia assemblage at Chengjiang, Kunmingella – Cricocosmia assemblage at Haikou, and Kunmingella – Wutingaspis – Obolus assemblage at Anning and Wuding. These sites yield new and striking specimens, such as a new tentacular animal, brachiopods with pedicles preserved, and the enigmatic Xidazoon (having mixed phyla characters), which are significant in our understanding of animal phylogeny. Above all, the appearance of diverse chordates and agnathans (vertebrates) greatly expands our knowledge of the Cambrian explosion. The discovery of soft-bodied fossils at many new localities and the very wide distribution of the Qiongzhusi Formation suggest that many more localities remain to be discovered. Here, a new early form of tentaculate, Cambrotentacus sanwuia gen. et sp. nov. (perhaps related to lophophorates and entoprocts), is described.",
    url = "https://doi.org/10.1144/jgs.158.2.211",
    doi = "10.1144/jgs.158.2.211",
    openalex = "W2151545253",
    references = "doi10103821631, doi101038326181a0, doi101038387489a0, doi10103846965, doi101073pnas9794453, doi10108003115517908565437, doi101126science7886451, doi1011300091761319940220179pcbgsr23co2, doi101826182003741571989, doi101826182003769311997, doi105860choice501469, dzik1988the, morris1987a, openalexw1573076930"
}

@misc{crossref2003chinese,
    title = "Chinese Femininities/Chinese Masculinities",
    year = "2003",
    url = "https://doi.org/10.1525/9780520935303",
    doi = "10.1525/9780520935303",
    openalex = "W4387485256"
}

Exceptionally preserved, non-biomineralizing fossils contribute importantly to resolving details of the Cambrian explosion, but little to its overall patterns. Six distinct "types" of exceptional preservation are identified for the terminal Proterozoic-Cambrian interval, each of which is dependent on particular taphonomic circumstances, typically restricted both in space and time. Taphonomic pathways yielding exceptional preservation were particularly variable through the Proterozoic-Cambrian transition, at least in part a consequence of contemporaneous evolutionary innovations. Combined with the reasonably continuous record of "Doushantuo-type preservation," and the fundamentally more robust records of shelly fossils, phytoplankton cysts and trace fossils, these taphonomic perturbations contribute to the documentation of major evolutionary and biogeochemical shifts through the terminal Proterozoic and early Cambrian.Appreciation of the relationship between taphonomic pathway and fossil expression serves as a useful tool for interpreting exceptionally preserved, often problematic, early Cambrian fossils. In shale facies, for example, flattened non-biomineralizing structures typically represent the remains of degradation-resistant acellular and extracellular "tissues" such as chaetae and cuticles, whereas three-dimensional preservation represents labile cellular tissues with a propensity for attracting and precipitating early diagenetic minerals. Such distinction helps to identify the acuticular integument of hyolithids, the chaetae-like nature of Wiwaxia sclerites, the chaetognath-like integument of Amiskwia, the midgut glands of various Burgess Shale arthropods, and the misidentification of deposit-feeding arthropods in the Chengjiang biota. By the same reasoning, putative lobopods in the Sirius Passet biota and putative deuterostomes in the Chengiang biota are better interpreted as arthropods.

@article{doi101093icb431166,
    author = "Butterfield, Nicholas J.",
    title = "Exceptional Fossil Preservation and the Cambrian Explosion",
    year = "2003",
    journal = "Integrative and Comparative Biology",
    abstract = {Exceptionally preserved, non-biomineralizing fossils contribute importantly to resolving details of the Cambrian explosion, but little to its overall patterns. Six distinct "types" of exceptional preservation are identified for the terminal Proterozoic-Cambrian interval, each of which is dependent on particular taphonomic circumstances, typically restricted both in space and time. Taphonomic pathways yielding exceptional preservation were particularly variable through the Proterozoic-Cambrian transition, at least in part a consequence of contemporaneous evolutionary innovations. Combined with the reasonably continuous record of "Doushantuo-type preservation," and the fundamentally more robust records of shelly fossils, phytoplankton cysts and trace fossils, these taphonomic perturbations contribute to the documentation of major evolutionary and biogeochemical shifts through the terminal Proterozoic and early Cambrian.Appreciation of the relationship between taphonomic pathway and fossil expression serves as a useful tool for interpreting exceptionally preserved, often problematic, early Cambrian fossils. In shale facies, for example, flattened non-biomineralizing structures typically represent the remains of degradation-resistant acellular and extracellular "tissues" such as chaetae and cuticles, whereas three-dimensional preservation represents labile cellular tissues with a propensity for attracting and precipitating early diagenetic minerals. Such distinction helps to identify the acuticular integument of hyolithids, the chaetae-like nature of Wiwaxia sclerites, the chaetognath-like integument of Amiskwia, the midgut glands of various Burgess Shale arthropods, and the misidentification of deposit-feeding arthropods in the Chengjiang biota. By the same reasoning, putative lobopods in the Sirius Passet biota and putative deuterostomes in the Chengiang biota are better interpreted as arthropods.},
    url = "https://doi.org/10.1093/icb/43.1.166",
    doi = "10.1093/icb/43.1.166",
    openalex = "W2181027699",
    references = "doi1010160016703789901919, doi101017s000632310000548x, doi101017s0094837300009994, doi101017s0094837300012082, doi10103834391, doi10103835318, doi101098rstb19790006, doi101098rstb19850005, doi101111j1469185x1999tb00046x, doi101111j150239311975tb01311x, doi101111j150239311994tb01558x, doi101111j150239311995tb01587x, doi101111j150239311995tb01591x, doi101126science1066611, doi101126science28153801173, doi1016660094837320000260386bpngns20co2, doi1016660094837320020280155lgatio20co2, doi1023073514743, doi1023073515360, openalexw2326083785, openalexw2754161204, openalexw3127114020, openalexw659399033"
}

The uniramous ‘great appendages’ of several arthropods from the Early to Middle Cambrian are a characteristic pair of pre-oral limbs, which served for prey capture. It has been assumed that the morphological differences between the ‘great-appendage’ arthropods indicate that raptorial antero-ventral and anteriorly pointing appendages evolved more than once in arthropod phylogeny. One set of Cambrian ‘great-appendage’ arthropods has, however, very similar short antero-ventral appendages with a peduncle of two segments angled against each other (elbowed) and with stout distally or medio-distally directed spines or long flexible flagellate spines on each of the four distal segments. Moreover, the head appendages of all these forms comprise the ‘great appendages’ and three pairs of biramous limbs. To this set of taxa we can add a new form from the Lower Cambrian Maotianshan Shale of southern China, Haikoucaris ercaiensis n. gen. and n. sp. It is known from three specimens, possibly being little abundant in the faunal community. It can be distinguished from all other taxa by the prominence of the proximal claw segment of its ‘great appendages’ and by only three distal spines (one on each of the distal segments). The similarity of the short, spiky ‘great appendages’ of Haikoucaris with the chelicera of the Chelicerata leads us to hypothesize that this particular type of ‘great appendages’ was the actual precursor of the chelicera. Homeobox gene and developmental data recently demonstrated the homology between the antenna of ateloceratans and the antennula of crustaceans on one side and the chelicera of chelicerates on the other. To this we add palaeontological evidence for the homology between the chelicerae of chelicerates and the ‘short great appendages’ of certain Cambrian arthropods, which leads us to hypothesize that the evolutionary path went from the ‘short great appendages’, by progressive compaction, toward the chelicera with only a two-spined chela. The new form from China is regarded as the possible latest offshoot, whereas the other ‘great appendages’ arthropods with similar short grasping limbs were derivatives of the stem lineage of the crown-group Chelicerata. Consequently, the chelicera with a chela with one fixed and one mobile finger is an autapomorphy of the crown group of Chelicerata, whereas a raptorial, but more limb-like antenna, with more distal spine-bearing segments, characterized the ground pattern of Chelicerata. Further taxa having ‘great appendages’, including the large Anomalocarididae, are also discussed in the light of their possible affinities to the Chelicerata and possible monophyly of all of these arthropods with raptorial anterior appendages.

@article{doi10108000241160410004764,
    author = "Chen, Junyuan and Waloszek, Dieter and Maas, Andreas",
    title = "A new ‘great‐appendage’ arthropod from the Lower Cambrian of China and homology of chelicerate chelicerae and raptorial antero‐ventral appendages",
    year = "2004",
    journal = "Lethaia",
    abstract = "The uniramous ‘great appendages’ of several arthropods from the Early to Middle Cambrian are a characteristic pair of pre-oral limbs, which served for prey capture. It has been assumed that the morphological differences between the ‘great-appendage’ arthropods indicate that raptorial antero-ventral and anteriorly pointing appendages evolved more than once in arthropod phylogeny. One set of Cambrian ‘great-appendage’ arthropods has, however, very similar short antero-ventral appendages with a peduncle of two segments angled against each other (elbowed) and with stout distally or medio-distally directed spines or long flexible flagellate spines on each of the four distal segments. Moreover, the head appendages of all these forms comprise the ‘great appendages’ and three pairs of biramous limbs. To this set of taxa we can add a new form from the Lower Cambrian Maotianshan Shale of southern China, Haikoucaris ercaiensis n. gen. and n. sp. It is known from three specimens, possibly being little abundant in the faunal community. It can be distinguished from all other taxa by the prominence of the proximal claw segment of its ‘great appendages’ and by only three distal spines (one on each of the distal segments). The similarity of the short, spiky ‘great appendages’ of Haikoucaris with the chelicera of the Chelicerata leads us to hypothesize that this particular type of ‘great appendages’ was the actual precursor of the chelicera. Homeobox gene and developmental data recently demonstrated the homology between the antenna of ateloceratans and the antennula of crustaceans on one side and the chelicera of chelicerates on the other. To this we add palaeontological evidence for the homology between the chelicerae of chelicerates and the ‘short great appendages’ of certain Cambrian arthropods, which leads us to hypothesize that the evolutionary path went from the ‘short great appendages’, by progressive compaction, toward the chelicera with only a two-spined chela. The new form from China is regarded as the possible latest offshoot, whereas the other ‘great appendages’ arthropods with similar short grasping limbs were derivatives of the stem lineage of the crown-group Chelicerata. Consequently, the chelicera with a chela with one fixed and one mobile finger is an autapomorphy of the crown group of Chelicerata, whereas a raptorial, but more limb-like antenna, with more distal spine-bearing segments, characterized the ground pattern of Chelicerata. Further taxa having ‘great appendages’, including the large Anomalocarididae, are also discussed in the light of their possible affinities to the Chelicerata and possible monophyly of all of these arthropods with raptorial anterior appendages.",
    url = "https://doi.org/10.1080/00241160410004764",
    doi = "10.1080/00241160410004764",
    openalex = "W1763189032",
    references = "doi1010079789401149044, doi101017s002233600002758x, doi101038337695c0, doi101038417271a, doi101046j1525142x200202034x, doi101073pnas951810665, doi101073pnas951810671, doi101098rspb19980385, doi101098rstb19810033, doi1011111475498300244, doi101111j150239311990tb01373x, doi1016660094837320020280155lgatio20co2, doi101826182003769311997, doi104095103458, doi105281zenodo16490103, doi105860choice395182, dzik1988the, openalexw2240758963, xianguang1999new"
}

@article{doi101130g206401,
    author = "Gabbott, Sarah E. and Hou, Xianguang and Norry, Michael J and Siveter, David J.",
    title = "Preservation of Early Cambrian animals of the Chengjiang biota",
    year = "2004",
    journal = "Geology",
    url = "https://doi.org/10.1130/g20640.1",
    doi = "10.1130/g20640.1",
    openalex = "W2031748285",
    references = "briggs2003the, doi101016001670379390433w, doi1010160016703793904512, doi101016s0016703700003872, doi101016s0016703796003213, doi101016s0016703796003225, doi101017s0094837300009994, doi101038361436a0, doi101093icb431166, doi101111j150239311995tb01587x, doi101126science28153801173, doi1016660094837320020280155lgatio20co2, doi105860choice416546, openalexw2912219260"
}

Foreword.Preface.Part I: Geological And Evolutionary Setting of The Biota.1. Geological Time And The Evolution Of Early Life On Earth.2. The Evolutionary Significance Of The Chengjiang Biota.3. The Discovery And Initial Study Of The Chengjiang Lagerstatte.4. The Distribution And Geological Setting Of The Chengjiang Lagerstatte.5. The Taphonomy And Preservation Of The Chengjiang Fossils.6. The Paleoecology Of The Chengjiang Biota.Part II: Chengjiang Fossils.7. Algae.8. Phylum Porifera.9. Phylum Cnidaria.10. Phylum Ctenophora.11. Phylum Nematomorpha.12. Phylum Priapulida.13. Phylum Hyolitha.14. Phylum Lobopodia.15. Anomalocarididae (Phylum Uncertain).16. Phylum Arthropoda.17. Phylum Brachiopoda.18. Phylum? Vetulicolia.19. Phylum Chordata.20. Enigmatic Animals.21. Species Recorded From The Chengjiang Biota.References.Index

@article{doi105860choice416546,
    title = "The Cambrian fossils of Chengjiang, China: the flowering of early animal life",
    year = "2004",
    journal = "Choice Reviews Online",
    abstract = "Foreword.Preface.Part I: Geological And Evolutionary Setting of The Biota.1. Geological Time And The Evolution Of Early Life On Earth.2. The Evolutionary Significance Of The Chengjiang Biota.3. The Discovery And Initial Study Of The Chengjiang Lagerstatte.4. The Distribution And Geological Setting Of The Chengjiang Lagerstatte.5. The Taphonomy And Preservation Of The Chengjiang Fossils.6. The Paleoecology Of The Chengjiang Biota.Part II: Chengjiang Fossils.7. Algae.8. Phylum Porifera.9. Phylum Cnidaria.10. Phylum Ctenophora.11. Phylum Nematomorpha.12. Phylum Priapulida.13. Phylum Hyolitha.14. Phylum Lobopodia.15. Anomalocarididae (Phylum Uncertain).16. Phylum Arthropoda.17. Phylum Brachiopoda.18. Phylum? Vetulicolia.19. Phylum Chordata.20. Enigmatic Animals.21. Species Recorded From The Chengjiang Biota.References.Index",
    url = "https://doi.org/10.5860/choice.41-6546",
    doi = "10.5860/choice.41-6546",
    openalex = "W1529107977"
}

@article{doi101016jasd200501005,
    author = "Waloszek, Dieter and Chen, Junyuan and Maas, Andreas and Wang, Xiuqiang",
    title = "Early Cambrian arthropods—new insights into arthropod head and structural evolution",
    year = "2005",
    journal = "Arthropod Structure \& Development",
    url = "https://doi.org/10.1016/j.asd.2005.01.005",
    doi = "10.1016/j.asd.2005.01.005",
    openalex = "W2055080029",
    references = "doi1010079789401149044, doi101016jympev200307013, doi101017s1464793103006274, doi101038326181a0, doi10103835093097, doi101038417271a, doi101046j1525142x200202034x, doi1016660094837320020280155lgatio20co2, doi10182618200049639197506, doi101826182003769311997, doi1023072992562, doi1023073515467, doi102517prpsj771, doi104095103962, doi105860choice416546, doi105860choice501469, maas2003morphology, morris1987a, openalexw2954279587"
}

@article{doi101016jpalaeo200303001,
    author = "Zhu, Maoyan and Babcock, Loren E. and Steiner, Michael",
    title = "Fossilization modes in the Chengjiang Lagerstätte (Cambrian of China): testing the roles of organic preservation and diagenetic alteration in exceptional preservation",
    year = "2005",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2003.03.001",
    doi = "10.1016/j.palaeo.2003.03.001",
    openalex = "W2138727135",
    references = "allison1988the, briggs1996the, doi1010160009254187901653, doi1010160016703784900899, doi101016001670379190005p, doi101017s0094837300012082, doi101098rstb19850134, doi101098rstb19850138, doi101126science29054971744, doi1011300091761319880160149mibbbs23co2, doi105860choice284524, doi105860choice300309"
}

A new genus and species of lightly sclerotized arthropod with an Aglaspis-like tagmosis, Kwanyinaspis maotianshanensis, is described from the well-known Chengjiang Lagerstätte, Early Cambrian, Yunnan, South China, on the basis of a single exquisitely preserved specimen. The dorsal exoskeleton, showing a poorly defined axial region but lacking axial furrows, is composed of a cephalic shield, 12 trunk tergites with well-developed pleural spines and a tail spine. A pair of ventral eyes is present beneath the first quarter of the cephalic shield. Appendages are preserved in remarkable detail; the basis is a large, flat plate, and bears gnathobases ventrally; the endopod is articulated with the abaxial edge of the basis and comprises seven articles; the exopod is flap-like and articulated along the entire length of the dorsal margin of the basis. Kwanyinaspis is provisionally assigned to Aglaspidida due to its overall resemblance to Aglaspis.

@article{doi10108003115510508619300,
    author = "Zhang, Xingliang and Shu, Degan",
    title = "A new arthropod from the Chengjiang Lagerstätte, Early Cambrian, southern China",
    year = "2005",
    journal = "Alcheringa An Australasian Journal of Palaeontology",
    abstract = "A new genus and species of lightly sclerotized arthropod with an Aglaspis-like tagmosis, Kwanyinaspis maotianshanensis, is described from the well-known Chengjiang Lagerstätte, Early Cambrian, Yunnan, South China, on the basis of a single exquisitely preserved specimen. The dorsal exoskeleton, showing a poorly defined axial region but lacking axial furrows, is composed of a cephalic shield, 12 trunk tergites with well-developed pleural spines and a tail spine. A pair of ventral eyes is present beneath the first quarter of the cephalic shield. Appendages are preserved in remarkable detail; the basis is a large, flat plate, and bears gnathobases ventrally; the endopod is articulated with the abaxial edge of the basis and comprises seven articles; the exopod is flap-like and articulated along the entire length of the dorsal margin of the basis. Kwanyinaspis is provisionally assigned to Aglaspidida due to its overall resemblance to Aglaspis.",
    url = "https://doi.org/10.1080/03115510508619300",
    doi = "10.1080/03115510508619300",
    openalex = "W1988692380",
    references = "doi101016003101829390065q, doi101017s0022336000027761, doi101017s0263593300000596, doi101038075246b0, doi101038114085a0, doi1011301052517320010110004tcbrot20co2, doi101144jgs1582211, doi101826182003769311997, doi1023073515467, doi105860choice416546"
}

Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540-520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is still an open issue. Here we provide compelling evidence that chaetognaths, an important element of modern zooplankton, were present in the Early Cambrian Chengjiang biota with morphologies almost identical to Recent forms. New information obtained from the lowermost Cambrian of China added to previous studies provide convincing evidence that protoconodont-bearing animals also belonged to chaetognaths. Chaetognaths were probably widespread and diverse in the earliest Cambrian. The obvious raptorial function of their circumoral apparatuses (grasping spines) places them among the earliest active predator metazoans. Morphology, body ratios and distribution suggest that the ancestral chaetognaths were planktonic with possible ecological preferences for hyperbenthic niches close to the sea bottom. Our results point to the early introduction of prey-predator relationships into the pelagic realm, and to the increase of trophic complexity (three-level structure) during the Precambrian-Cambrian transition, thus laying the foundations of present-day marine food chains.

@article{doi101098rspb20063761,
    author = "Vannier, Jean and Steiner, Michael and Renvoisé, Élodie and Hu, Shixue and Casanova, Jean-Paul",
    title = "Early Cambrian origin of modern food webs: evidence from predator arrow worms",
    year = "2006",
    journal = "Proceedings of the Royal Society B Biological Sciences",
    abstract = "Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540-520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is still an open issue. Here we provide compelling evidence that chaetognaths, an important element of modern zooplankton, were present in the Early Cambrian Chengjiang biota with morphologies almost identical to Recent forms. New information obtained from the lowermost Cambrian of China added to previous studies provide convincing evidence that protoconodont-bearing animals also belonged to chaetognaths. Chaetognaths were probably widespread and diverse in the earliest Cambrian. The obvious raptorial function of their circumoral apparatuses (grasping spines) places them among the earliest active predator metazoans. Morphology, body ratios and distribution suggest that the ancestral chaetognaths were planktonic with possible ecological preferences for hyperbenthic niches close to the sea bottom. Our results point to the early introduction of prey-predator relationships into the pelagic realm, and to the increase of trophic complexity (three-level structure) during the Precambrian-Cambrian transition, thus laying the foundations of present-day marine food chains.",
    url = "https://doi.org/10.1098/rspb.2006.3761",
    doi = "10.1098/rspb.2006.3761",
    openalex = "W2097634625",
    references = "doi1010160079661185900369, doi101016jgeobios200308001, doi101017s0094837300009994, doi101017s009483730001681x, doi101073pnas0400941101, doi101093icb431166, doi101093molbevmsh229, doi101111j150239311999tb00547x, doi101130g206401, doi10182618200067378198301, doi107312zhur10612, müller1991upper, openalexw2598873191, openalexw605188680, openalexw659399033, vandenboogaard1992upper"
}

@article{doi101016jpalaeo200703046,
    author = "Steiner, Michael and Li, Guoxiang and Qian, Yi and Zhu, Maoyan and Erdtmann, Bernd-Dietrich",
    title = "Neoproterozoic to Early Cambrian small shelly fossil assemblages and a revised biostratigraphic correlation of the Yangtze Platform (China)",
    year = "2007",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2007.03.046",
    doi = "10.1016/j.palaeo.2007.03.046",
    openalex = "W2057260077",
    references = "brasier1987microfossils, doi101017s0016756800007603, doi101017s0022336000036465, doi10103835318, doi10108008120099608728282, doi101111j14754983200500484x, doi101111j150239311988tb02083x, doi101126science11539488, doi101126science2795352879, doi1011300091761319940220179pcbgsr23co2, doi1011300091761319950230407scirpo23co2, doi1011300091761320030310431eocana20co2, doi101144gsjgs13130289, doi1016660022336020020760347mcciat20co2, doi1016660094837320000260334cmitsr20co2, doi101826182003741571989, doi10182618200376656199701, openalexw2473761340, openalexw566083668"
}

Abstract Fuxianhuia from the Chengjiang fauna is one of the least derived Cambrian arthropods. A supposed pair of hook-shaped post-antennal appendages (Chen et al. 1995) was later reinterpreted as a pair of gut diverticula situated in a carapace fold (Waloszek et al. 2005). The latter interpretation of the diverticular nature of this structure is verified, but we show that the diverticula are situated inside a head capsule. This capsule carries a pair of antennae. It is shown that the head has also a pair of ordinary locomotory limbs. It is also demonstrated that a number of body segments have more than one pair of legs. There is indication of a possible pair of small eyes in addition to the large pair. The gut may include sediment from the substrate, which indicates that sediment was ingested. Fuxianhuiids share with many lobopodians characters such as a lack of specialisation between and within the ventral appendages. The exopod rises as a lateral fold on a straight limb axis, indicating an origin as a secondary addition to a uniramous limb. The terms Arthropoda s.l. (or pan-Arthropoda) and Arthropoda s.s. are replaced by Aiolopoda Hou & Bergström, 2006, and Arthropoda (in the original sense). The origination of the arthropods is discussed.

@article{doi10108011035890809452772,
    author = "Bergström, Jan and Hou, Xianguang and Zhang, Xiguang and Clausen, Sébastien",
    title = "A New View of the Cambrian Arthropod Fuxianhuia",
    year = "2008",
    journal = "GFF",
    abstract = "Abstract Fuxianhuia from the Chengjiang fauna is one of the least derived Cambrian arthropods. A supposed pair of hook-shaped post-antennal appendages (Chen et al. 1995) was later reinterpreted as a pair of gut diverticula situated in a carapace fold (Waloszek et al. 2005). The latter interpretation of the diverticular nature of this structure is verified, but we show that the diverticula are situated inside a head capsule. This capsule carries a pair of antennae. It is shown that the head has also a pair of ordinary locomotory limbs. It is also demonstrated that a number of body segments have more than one pair of legs. There is indication of a possible pair of small eyes in addition to the large pair. The gut may include sediment from the substrate, which indicates that sediment was ingested. Fuxianhuiids share with many lobopodians characters such as a lack of specialisation between and within the ventral appendages. The exopod rises as a lateral fold on a straight limb axis, indicating an origin as a secondary addition to a uniramous limb. The terms Arthropoda s.l. (or pan-Arthropoda) and Arthropoda s.s. are replaced by Aiolopoda Hou \& Bergström, 2006, and Arthropoda (in the original sense). The origination of the arthropods is discussed.",
    url = "https://doi.org/10.1080/11035890809452772",
    doi = "10.1080/11035890809452772",
    openalex = "W1994033641",
    references = "doi1010079789401149044, doi101016jasd200501005, doi101016jpalaeo200703027, doi101038114085a0, doi101038417271a, doi101098rstb19810164, doi101111j14754983200700746x, doi101111j150239311996tb01831x, doi101126science26451631304, doi101826182003769311997, openalexw650377807"
}

Although Cambrian Burgess Shale–type (BST) biotas are fundamental to understanding the radiation of metazoans, the nature of their extraordinary preservation remains controversial. There remains disagreement about the importance of the role of early mineral replication of soft tissues versus the conservation of primary organic remains. Most prior work focused on soft-bodied fossils from the two most important BST biotas, those of the Burgess Shale (Canada) and Maotianshan Shale (Chengjiang, China). Fossils from these two deposits do not provide ideal candidates for specimen-level taphonomic study because they have been altered: the Burgess Shale by greenschist facies metamorphism and the Maotianshan Shale by intensive subsurface weathering. Elemental mapping of soft-bodied fossils from 11 other BST deposits worldwide demonstrates that BST preservation represents a single major taphonomic pathway that may share a common cause wherever it occurs. The conservation of organic tissues, and not early authigenic mineralization, is the primary mechanism responsible for the preservation of BST assemblages. Early authigenic mineral replacement preserves certain anatomical features of some specimens, but the preservation of non-biomineralized BST fossils requires suppression of the processes that normally lead to the degradation of organic remains in marine environments.

@article{doi101130g24961a1,
    author = "Gaines, Robert R. and Briggs, Derek E. G. and Yuanlong, Zhao",
    title = "Cambrian Burgess Shale–type deposits share a common mode of fossilization",
    year = "2008",
    journal = "Geology",
    abstract = "Although Cambrian Burgess Shale–type (BST) biotas are fundamental to understanding the radiation of metazoans, the nature of their extraordinary preservation remains controversial. There remains disagreement about the importance of the role of early mineral replication of soft tissues versus the conservation of primary organic remains. Most prior work focused on soft-bodied fossils from the two most important BST biotas, those of the Burgess Shale (Canada) and Maotianshan Shale (Chengjiang, China). Fossils from these two deposits do not provide ideal candidates for specimen-level taphonomic study because they have been altered: the Burgess Shale by greenschist facies metamorphism and the Maotianshan Shale by intensive subsurface weathering. Elemental mapping of soft-bodied fossils from 11 other BST deposits worldwide demonstrates that BST preservation represents a single major taphonomic pathway that may share a common cause wherever it occurs. The conservation of organic tissues, and not early authigenic mineralization, is the primary mechanism responsible for the preservation of BST assemblages. Early authigenic mineral replacement preserves certain anatomical features of some specimens, but the preservation of non-biomineralized BST fossils requires suppression of the processes that normally lead to the degradation of organic remains in marine environments.",
    url = "https://doi.org/10.1130/g24961a.1",
    doi = "10.1130/g24961a.1",
    openalex = "W2162666312",
    references = "briggs2003the, doi101016jchemgeo200409003, doi101016jpalaeo200306001, doi101016jpalaeo200407034, doi101017s0094837300009994, doi101038114085a0, doi101093icb431166, doi101098rstb19810007, doi101111j14754983200700656x, doi101111j150239311995tb01587x, doi101126science28153801173, doi101130g206401, doi101139e06012, doi1016660094837320020280155lgatio20co2, doi102517prpsj771, openalexw2527820321, openalexw2912219260, openalexw3127114020"
}

The Middle Cambrian Spence Shale Member (Langston Formation) and Wheeler and Marjum Formations of Utah are known to contain a diverse soft-bodied fauna, but important new paleontological material continues to be uncovered from these strata. New specimens of anomalocaridids include the largest and smallest near complete examples yet reported from Utah. New material of stem group arthropods includes two new genera and species of arachnomorphs: Nettapezoura basilika and Dicranocaris guntherorum. Other new arachnomorph material includes a new species of Leanchoilia comparable to L. protogonia Simonetta, 1970; Leanchoilia superlata? Walcott, 1912; Sidneyia Walcott, 1911a; and Mollisonia symmetrica Walcott, 1912. L. protogonia from the Burgess Shale is confirmed as a separate species and is not a composite fossil. The first example of the trilobite Elrathia kingii preserving traces of the appendages is described. In addition, new material of the bivalved arthropods Canadaspis Novozhilov in Orlov, 1960; Branchiocaris Briggs, 1976; Waptia Walcott, 1912; and Isoxys Walcott, 1890 is described.

@article{doi101666060861,
    author = "Briggs, Derek E. G. and Lieberman, Bruce S. and Hendricks, Jonathan R. and Halgedahl, Susan L. and Jarrard, Richard D.",
    title = "Middle Cambrian arthropods from Utah",
    year = "2008",
    journal = "Journal of Paleontology",
    abstract = "The Middle Cambrian Spence Shale Member (Langston Formation) and Wheeler and Marjum Formations of Utah are known to contain a diverse soft-bodied fauna, but important new paleontological material continues to be uncovered from these strata. New specimens of anomalocaridids include the largest and smallest near complete examples yet reported from Utah. New material of stem group arthropods includes two new genera and species of arachnomorphs: Nettapezoura basilika and Dicranocaris guntherorum. Other new arachnomorph material includes a new species of Leanchoilia comparable to L. protogonia Simonetta, 1970; Leanchoilia superlata? Walcott, 1912; Sidneyia Walcott, 1911a; and Mollisonia symmetrica Walcott, 1912. L. protogonia from the Burgess Shale is confirmed as a separate species and is not a composite fossil. The first example of the trilobite Elrathia kingii preserving traces of the appendages is described. In addition, new material of the bivalved arthropods Canadaspis Novozhilov in Orlov, 1960; Branchiocaris Briggs, 1976; Waptia Walcott, 1912; and Isoxys Walcott, 1890 is described.",
    url = "https://doi.org/10.1666/06-086.1",
    doi = "10.1666/06-086.1",
    openalex = "W2129198432",
    references = "doi101098rstb19810033"
}

@article{crossref2010the,
    title = "The Oxford Chinese dictionary: English/Chinese - Chinese/English",
    year = "2010",
    journal = "Choice Reviews Online",
    url = "https://doi.org/10.5860/choice.48-1808",
    doi = "10.5860/choice.48-1808",
    number = "04",
    openalex = "W609166324",
    pages = "48-1808-48-1808",
    volume = "48"
}

Abstract: The lower Cambrian Emu Bay Shale on Kangaroo Island, South Australia, contains the only known Cambrian Burgess Shale‐type biota in Australia. Two new lamellipedian arthropods, Emucaris fava gen. et sp. nov. and Kangacaris zhangi gen. et sp. nov., from the Emu Bay Shale Lagerstätte are described as monotypic genera that are resolved cladistically as a monophyletic group that is sister to Naraoiidae + Liwiidae and classified within the Nektaspida as a new family Emucarididae. Shared derived characters of Emucarididae involve a bipartite, elongate hypostome and elongation of the pygidium relative to the cephalic shield and very short thorax. A monophyletic Liwiidae is composed of Liwia and the Ordovician Tariccoia + Soomaspis but excludes Buenaspis, and even the membership of Buenaspis in Nektaspida is contradicted amongst the shortest cladograms. New morphological interpretations favour affinities of Kwanyinaspis with Conciliterga rather than with Aglaspidida, and Phytophilaspis with Petalopleura.

@article{doi101111j14754983201000932x,
    author = "Paterson, John R. and Edgecombe, Gregory D. and García‐Bellido, Diego C. and Jago, J. B. and Gehlîng, James G.",
    title = "Nektaspid arthropods from the Lower Cambrian Emu Bay Shale Lagerstätte, South Australia, with a reassessment of lamellipedian relationships",
    year = "2010",
    journal = "Palaeontology",
    abstract = "Abstract: The lower Cambrian Emu Bay Shale on Kangaroo Island, South Australia, contains the only known Cambrian Burgess Shale‐type biota in Australia. Two new lamellipedian arthropods, Emucaris fava gen. et sp. nov. and Kangacaris zhangi gen. et sp. nov., from the Emu Bay Shale Lagerstätte are described as monotypic genera that are resolved cladistically as a monophyletic group that is sister to Naraoiidae + Liwiidae and classified within the Nektaspida as a new family Emucarididae. Shared derived characters of Emucarididae involve a bipartite, elongate hypostome and elongation of the pygidium relative to the cephalic shield and very short thorax. A monophyletic Liwiidae is composed of Liwia and the Ordovician Tariccoia + Soomaspis but excludes Buenaspis, and even the membership of Buenaspis in Nektaspida is contradicted amongst the shortest cladograms. New morphological interpretations favour affinities of Kwanyinaspis with Conciliterga rather than with Aglaspidida, and Phytophilaspis with Petalopleura.",
    url = "https://doi.org/10.1111/j.1475-4983.2010.00932.x",
    doi = "10.1111/j.1475-4983.2010.00932.x",
    openalex = "W2152987321",
    references = "doi10108003115510508619300, doi101666060821, doi105962bhltitle14915"
}

Molecular and morphological evidence unite the hemichordates and echinoderms as the Ambulacraria, but their earliest history remains almost entirely conjectural. This is on account of the morphological disparity of the ambulacrarians and a paucity of obvious stem-groups. We describe here a new taxon Herpetogaster collinsi gen. et sp. nov. from the Burgess Shale (Middle Cambrian) Lagerstätte. This soft-bodied vermiform animal has a pair of elongate dendritic oral tentacles, a flexible stolon with an attachment disc, and a re-curved trunk with at least 13 segments that is directed dextrally. A differentiated but un-looped gut is enclosed in a sac suspended by mesenteries. It consists of a short pharynx, a conspicuous lenticular stomach, followed by a narrow intestine sub-equal in length. This new taxon, together with the Lower Cambrian Phlogites and more intriguingly the hitherto enigmatic discoidal eldoniids (Cambrian-Devonian), form a distinctive clade (herein the cambroernids). Although one hypothesis of their relationships would look to the lophotrochozoans (specifically the entoprocts), we suggest that the evidence is more consistent with their being primitive deuterostomes, with specific comparisons being made to the pterobranch hemichordates and pre-radial echinoderms. On this basis some of the earliest ambulacrarians are interpreted as soft-bodied animals with a muscular stalk, and possessing prominent tentacles.

@article{doi101371journalpone0009586,
    author = "Caron, Jean-Bernard and Conway Morris, Simon and Shu, Degan",
    title = "Tentaculate fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) interpreted as primitive deuterostomes.",
    year = "2010",
    journal = "PloS one",
    abstract = "Molecular and morphological evidence unite the hemichordates and echinoderms as the Ambulacraria, but their earliest history remains almost entirely conjectural. This is on account of the morphological disparity of the ambulacrarians and a paucity of obvious stem-groups. We describe here a new taxon Herpetogaster collinsi gen. et sp. nov. from the Burgess Shale (Middle Cambrian) Lagerstätte. This soft-bodied vermiform animal has a pair of elongate dendritic oral tentacles, a flexible stolon with an attachment disc, and a re-curved trunk with at least 13 segments that is directed dextrally. A differentiated but un-looped gut is enclosed in a sac suspended by mesenteries. It consists of a short pharynx, a conspicuous lenticular stomach, followed by a narrow intestine sub-equal in length. This new taxon, together with the Lower Cambrian Phlogites and more intriguingly the hitherto enigmatic discoidal eldoniids (Cambrian-Devonian), form a distinctive clade (herein the cambroernids). Although one hypothesis of their relationships would look to the lophotrochozoans (specifically the entoprocts), we suggest that the evidence is more consistent with their being primitive deuterostomes, with specific comparisons being made to the pterobranch hemichordates and pre-radial echinoderms. On this basis some of the earliest ambulacrarians are interpreted as soft-bodied animals with a muscular stalk, and possessing prominent tentacles.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC2833208/",
    doi = "10.1371/journal.pone.0009586",
    openalex = "W2023015944",
    pmcid = "PMC2833208",
    pmid = "20221405",
    references = "doi101038nature06614, doi101098rspb20090896, doi101111j175348871981tb06752x, doi101126science9231776, doi101126science972526482b, doi1023071483846, doi1023073390, doi105860choice273873, openalexw1904943263, openalexw3104090091, openalexw645459046"
}

@article{doi101016jprecamres201112004,
    author = "Cremonese, Lorenzo and Shields, Graham and Struck, Ulrich and Ling, Hong‐Fei and Och, Lawrence M. and Chen, Xi and Li, Da",
    title = "Marine biogeochemical cycling during the early Cambrian constrained by a nitrogen and organic carbon isotope study of the Xiaotan section, South China",
    year = "2011",
    journal = "Precambrian Research",
    url = "https://doi.org/10.1016/j.precamres.2011.12.004",
    doi = "10.1016/j.precamres.2011.12.004",
    openalex = "W1976518385",
    references = "doi101016jpalaeo200306001, doi101016jpalaeo201003048, doi101098rspb20063761"
}

Abstract Data on the first appearances of major animal groups with mineralized skeletons on the Siberian Platform and worldwide are revised and summarized herein with references to an improved carbon isotope stratigraphy and radiometric dating in order to reconstruct the Cambrian radiation (popularly known as the ‘Cambrian explosion’) with a higher precision and provide a basis for the definition of Cambrian Stages 2 to 4. The Lophotrochozoa and, probably, Chaetognatha were first among protostomians to achieve biomineralization during the Terreneuvian Epoch, mainly the Fortunian Age. Fast evolutionary radiation within the Lophotrochozoa was followed by radiation of the sclerotized and biomineralized Ecdysozoa during Stage 3. The first mineralized skeletons of the Deuterostomia, represented by echinoderms, appeared in the middle of Cambrian Stage 3. The fossil record of sponges and cnidarians suggests that they acquired biomineralized skeletons in the late Neoproterozoic, but diversification of both definite sponges and cnidarians was in parallel to that of bilaterians. The distribution of calcium carbonate skeletal mineralogies from the upper Ediacaran to lower Cambrian reflects fluctuations in the global ocean chemistry and shows that the Cambrian radiation occurred mainly during a time of aragonite and high-magnesium calcite seas.

@article{doi101017s0016756811000720,
    author = "Kouchinsky, Artem and Bengtson, Stefan and Runnegar, Bruce and Skovsted, Christian B. and Steiner, Michael and Vendrasco, Michael J.",
    title = "Chronology of early Cambrian biomineralization",
    year = "2011",
    journal = "Geological Magazine",
    abstract = "Abstract Data on the first appearances of major animal groups with mineralized skeletons on the Siberian Platform and worldwide are revised and summarized herein with references to an improved carbon isotope stratigraphy and radiometric dating in order to reconstruct the Cambrian radiation (popularly known as the ‘Cambrian explosion’) with a higher precision and provide a basis for the definition of Cambrian Stages 2 to 4. The Lophotrochozoa and, probably, Chaetognatha were first among protostomians to achieve biomineralization during the Terreneuvian Epoch, mainly the Fortunian Age. Fast evolutionary radiation within the Lophotrochozoa was followed by radiation of the sclerotized and biomineralized Ecdysozoa during Stage 3. The first mineralized skeletons of the Deuterostomia, represented by echinoderms, appeared in the middle of Cambrian Stage 3. The fossil record of sponges and cnidarians suggests that they acquired biomineralized skeletons in the late Neoproterozoic, but diversification of both definite sponges and cnidarians was in parallel to that of bilaterians. The distribution of calcium carbonate skeletal mineralogies from the upper Ediacaran to lower Cambrian reflects fluctuations in the global ocean chemistry and shows that the Cambrian radiation occurred mainly during a time of aragonite and high-magnesium calcite seas.",
    url = "https://doi.org/10.1017/s0016756811000720",
    doi = "10.1017/s0016756811000720",
    openalex = "W2127465210",
    references = "bengtson1976the, brasier1987microfossils, doi101002jemt10217, doi101002jezb21090, doi10100797814615074751, doi10100797814899242787, doi101016c20090644421, doi101016jpalaeo200401022, doi101016jpalaeo200703046, doi101016jpalaeo200902013, doi101016jpalwor200610014, doi101016s0031018298001096, doi101017s0022336000024963, doi101017s0022336000034879, doi101017s0022336000036465, doi101038326181a0, doi101038nature06614, doi101038nature07673, doi101093icb431166, doi101098rspb20063761, doi101111j109636421995tb00110x, doi101111j150239311975tb01311x, doi101111j150239311999tb00547x, doi101126science1107765, doi101126science2705236598, doi101127zdgg1111959434, doi101130g25094a1, doi101146annurevearth33092203122519, doi101666100651, doi10182618200067378198301, doi101826182003741571989, doi104202app20090058, doi105860choice304422, doi105860choice465038, doi105962bhltitle66379, morris1987a, openalexw2473761340, openalexw2598873191, openalexw3127114020, openalexw587905045, tiwari1999organicwalled"
}

China is undergoing rapid changes in sexual mores due to several reasons such as decreasing control of the state over private lives of individuals, globalization of its economy, and some policies initiated by the state. There is increased acceptance of premarital sex and extramarital sex in China, especially among youth. In historically conservative China, influenced by Confucian ideals of patriarchal dominance for centuries, the sexual freedom currently enjoyed by many is unprecedented. This has impacted women's status and sexual lives in several positive ways such as increasing freedom of sexual expression, control over their bodies, sexual choices, and increasing equality with men in all spheres of life. However several negative consequences such as a rise in STD/HIV prevalence, commercial sex, and divorce rates have also been attributed to the ongoing sexual revolution in China. Recommendations combating these and suggestions for directions in future research are discussed.

@article{doi101080095401212010532537,
    author = "Xiao, Zhiwen and Mehrotra, Purnima and Zimmerman, Rick S.",
    title = "Sexual revolution in China: implications for Chinese women and society",
    year = "2011",
    journal = "AIDS Care",
    abstract = "China is undergoing rapid changes in sexual mores due to several reasons such as decreasing control of the state over private lives of individuals, globalization of its economy, and some policies initiated by the state. There is increased acceptance of premarital sex and extramarital sex in China, especially among youth. In historically conservative China, influenced by Confucian ideals of patriarchal dominance for centuries, the sexual freedom currently enjoyed by many is unprecedented. This has impacted women's status and sexual lives in several positive ways such as increasing freedom of sexual expression, control over their bodies, sexual choices, and increasing equality with men in all spheres of life. However several negative consequences such as a rise in STD/HIV prevalence, commercial sex, and divorce rates have also been attributed to the ongoing sexual revolution in China. Recommendations combating these and suggestions for directions in future research are discussed.",
    url = "https://doi.org/10.1080/09540121.2010.532537",
    doi = "10.1080/09540121.2010.532537",
    openalex = "W2058458967",
    references = "doi101525srsp20041163"
}

A restudy of the Burgess Shale arthropod Emeraldella brocki suggests novel interpretations of its morphology. We show that the morphology is more plesiomorphic than previously assumed, particularly regarding tagmosis. The cephalon probably only incorporates three limb-bearing postantennular segments. The trunk is not differentiated and consists of 12 tergite-bearing segments and a styliform telson. Limb structure is generally similar to that of other artiopods except for a tripartite exopod and a high degree of differentiation of podomere proportions along the body. A phylogenetic analysis of 20 fossil arthropod taxa based on 36 characters renders E. brocki as a basal taxon within a monophyletic group that comprises all artiopods included. Autapomorphies of this taxon are a filiform antennula and a bilobate exopod that carries lamellae proximally. Trilobites are nested within a group of artiopods sharing a pygidium. Agnostus pisiformis is retrieved as the sister taxon to the stem-lineage crustacean Oelandocaris oelandica, and both constitute the sister taxon of Artiopoda. ‘Great appendage’ arthropods, traditionally included in the Arachnomorpha, are retrieved as sister to the Crustacea sensu lato + Artiopoda clade, which contradicts the arachnomorph concept.

@article{doi101080147720192011566634,
    author = "Stein, Martin and Selden, Paul A.",
    title = "A restudy of the Burgess Shale (Cambrian) arthropod Emeraldella brocki and reassessment of its affinities",
    year = "2011",
    journal = "Journal of Systematic Palaeontology",
    abstract = "A restudy of the Burgess Shale arthropod Emeraldella brocki suggests novel interpretations of its morphology. We show that the morphology is more plesiomorphic than previously assumed, particularly regarding tagmosis. The cephalon probably only incorporates three limb-bearing postantennular segments. The trunk is not differentiated and consists of 12 tergite-bearing segments and a styliform telson. Limb structure is generally similar to that of other artiopods except for a tripartite exopod and a high degree of differentiation of podomere proportions along the body. A phylogenetic analysis of 20 fossil arthropod taxa based on 36 characters renders E. brocki as a basal taxon within a monophyletic group that comprises all artiopods included. Autapomorphies of this taxon are a filiform antennula and a bilobate exopod that carries lamellae proximally. Trilobites are nested within a group of artiopods sharing a pygidium. Agnostus pisiformis is retrieved as the sister taxon to the stem-lineage crustacean Oelandocaris oelandica, and both constitute the sister taxon of Artiopoda. ‘Great appendage’ arthropods, traditionally included in the Arachnomorpha, are retrieved as sister to the Crustacea sensu lato + Artiopoda clade, which contradicts the arachnomorph concept.",
    url = "https://doi.org/10.1080/14772019.2011.566634",
    doi = "10.1080/14772019.2011.566634",
    openalex = "W2149698609",
    references = "doi10108003115510508619300, doi10108011035890809452772, doi101098rstb19810033, doi101111j10963642200900562x, doi101666060821, doi104095103458, openalexw2240758963"
}

Abstract: We redescribe the morphology of Yohoia tenuis (Chelicerata sensu lato) from the Cambrian Burgess Shale Lagerstätte. The morphology of the most anterior, prominent, so‐called great appendage changes throughout ontogeny. While its principal morphology remains unaltered, the length ratios of certain parts of the great appendage change significantly. Furthermore, it possesses a special jack‐knifing mechanism, i.e. an elbow joint: the articulation between the distal one of the two peduncle elements and the most proximal of the four spine‐bearing claw elements. This morphology might have enabled the animal to hunt like a modern spearer‐type mantis shrimp, an analogy enhanced by the similarly large and protruding eyes. For comparison, details of specimens of selected other great‐appendage arthropods from the Lower Cambrian Chengjiang Lagerstätte have been investigated using fluorescence microscopy. This revealed that the morphology of the great appendage of Y. tenuis is much like that of the Chengjiang species Fortiforceps foliosa and Jianfengia multisegmentalis. The morphology of the great appendage of the latter is even more similar to the morphology developed in early developmental stages of Y. tenuis, while the morphology of the great appendage of F. foliosa is more similar to that of later developmental stages of Y. tenuis. The arrangement of the elbow joint supports the view that the great appendage evolved into the chelicera of Chelicerata sensu stricto, as similar joints are found in various ingroup taxa such as Xiphosura, Opiliones or Palpigradi. With this, it also supports the interpretation of the great appendage to be homologous with the first appendage of other arthropods.

@article{doi101111j14754983201101124x,
    author = "Haug, Joachim T. and Waloszek, Dieter and Maas, Andreas and Liu, Yu and Haug, Carolin",
    title = "Functional morphology, ontogeny and evolution of mantis shrimp‐like predators in the Cambrian",
    year = "2011",
    journal = "Palaeontology",
    abstract = "Abstract: We redescribe the morphology of Yohoia tenuis (Chelicerata sensu lato) from the Cambrian Burgess Shale Lagerstätte. The morphology of the most anterior, prominent, so‐called great appendage changes throughout ontogeny. While its principal morphology remains unaltered, the length ratios of certain parts of the great appendage change significantly. Furthermore, it possesses a special jack‐knifing mechanism, i.e. an elbow joint: the articulation between the distal one of the two peduncle elements and the most proximal of the four spine‐bearing claw elements. This morphology might have enabled the animal to hunt like a modern spearer‐type mantis shrimp, an analogy enhanced by the similarly large and protruding eyes. For comparison, details of specimens of selected other great‐appendage arthropods from the Lower Cambrian Chengjiang Lagerstätte have been investigated using fluorescence microscopy. This revealed that the morphology of the great appendage of Y. tenuis is much like that of the Chengjiang species Fortiforceps foliosa and Jianfengia multisegmentalis. The morphology of the great appendage of the latter is even more similar to the morphology developed in early developmental stages of Y. tenuis, while the morphology of the great appendage of F. foliosa is more similar to that of later developmental stages of Y. tenuis. The arrangement of the elbow joint supports the view that the great appendage evolved into the chelicera of Chelicerata sensu stricto, as similar joints are found in various ingroup taxa such as Xiphosura, Opiliones or Palpigradi. With this, it also supports the interpretation of the great appendage to be homologous with the first appendage of other arthropods.",
    url = "https://doi.org/10.1111/j.1475-4983.2011.01124.x",
    doi = "10.1111/j.1475-4983.2011.01124.x",
    openalex = "W1562077884",
    references = "doi101007s0042700600854, doi101016jasd200501005, doi101017s002233600002758x, doi101038428819a, doi10108010635150390218330, doi10108011035890809452772, doi10108011035899509546213, doi101098rspb20090361, doi101098rstb19830020, doi101111j10963642200700284x, doi101111j10963642200900562x, doi101111j14754983200700649x, doi101111j14754983200900914x, doi101111j150239311999tb00547x, doi101126science1169514, doi101139e06012, doi101146annureven10010165000525, doi101242jeb01831, doi101666060171, doi101826182000751171987, doi1023072992562, doi1023073515467, doi104095103458, doi105281zenodo15992748, doi105281zenodo16490103, doi105860choice416546, doi105962bhltitle14915, doi105962bhltitle156765, maas2003morphology, openalexw2240758963, xianguang1999new"
}

Diverse bilaterian clades emerged apparently within a few million years during the early Cambrian, and various environmental, developmental, and ecological causes have been proposed to explain this abrupt appearance. A compilation of the patterns of fossil and molecular diversification, comparative developmental data, and information on ecological feeding strategies indicate that the major animal clades diverged many tens of millions of years before their first appearance in the fossil record, demonstrating a macroevolutionary lag between the establishment of their developmental toolkits during the Cryogenian [(850 to 635 million years ago (Ma)], and the later ecological success of metazoans during the Ediacaran (635 to 541 Ma) and Cambrian (541 to 488 Ma) periods. We argue that this diversification involved new forms of developmental regulation, as well as innovations in networks of ecological interaction within the context of permissive environmental circumstances.

@article{doi101126science1206375,
    author = "Erwin, Douglas H. and Laflamme, Marc and Tweedt, Sarah M. and Sperling, Erik A. and Pisani, Davide and Peterson, Kevin J.",
    title = "The Cambrian Conundrum: Early Divergence and Later Ecological Success in the Early History of Animals",
    year = "2011",
    journal = "Science",
    abstract = "Diverse bilaterian clades emerged apparently within a few million years during the early Cambrian, and various environmental, developmental, and ecological causes have been proposed to explain this abrupt appearance. A compilation of the patterns of fossil and molecular diversification, comparative developmental data, and information on ecological feeding strategies indicate that the major animal clades diverged many tens of millions of years before their first appearance in the fossil record, demonstrating a macroevolutionary lag between the establishment of their developmental toolkits during the Cryogenian [(850 to 635 million years ago (Ma)], and the later ecological success of metazoans during the Ediacaran (635 to 541 Ma) and Cambrian (541 to 488 Ma) periods. We argue that this diversification involved new forms of developmental regulation, as well as innovations in networks of ecological interaction within the context of permissive environmental circumstances.",
    url = "https://doi.org/10.1126/science.1206375",
    doi = "10.1126/science.1206375",
    openalex = "W2111414198",
    references = "doi101016jasd200910002, doi101016jpalwor200610016, doi101017s000632310000548x, doi101017s0016756800007603, doi101017s0016756811000720, doi101017s0022336000036465, doi101017s009483730001681x, doi101017s1089332600001133, doi10103835318, doi101038nature04894, doi101038nature05345, doi101038nature06811, doi101038nature09038, doi101038ngeo934, doi101073pnas0902322106, doi10108000241160410004764, doi10108003115510508619300, doi101093bioinformaticsbtg180, doi101093bioinformaticsbtp368, doi101093molbevmsl150, doi101093molbevmsm193, doi101098rstb20090038, doi101111j150239311989tb01332x, doi101111j150239311990tb01373x, doi101111j155856461987tb02459x, doi101126science1113832, doi101126science1135013, doi101126science1139158, doi101126science28454232129, doi1011300091761319940220179pcbgsr23co2, doi1011300091761320030310431eocana20co2, doi101144gsjgs14940607, doi101146annurevearth33092203122519, doi101146annurevecolsys35112202130124, doi101371journalpbio0040088, doi101371journalpbio1000602, doi101371journalpone0001121, doi101371journalpone0009586, doi10166609102r1, doi101826182003769311997, doi1018900012965819970781946paneoo20co2, doi1023072409086, doi10247510200701, doi104202app20090058, doi105962bhltitle82303"
}

Lobopodians, which diversified and flourished in the Cambrian seas, have long drawn much attention in that not only their extant close relatives, onychophorans and tardigrades, but euarthropods (Chelicerata, Myriapoda, Crustacea, and Hexapoda) may have been deeply rooted in stem-group lobopodians. Antennacanthopodia gracilis new genus and species is described and interpreted here as an “unarmoured” lobopodian from the Chengjiang fossil Lagerstätte (Early Cambrian, —520 Ma), Yunnan, southwestern China. This animal shares with other known Cambrian lobopodians such plesiomorphies (primitive characters) as onychophoran-like overall appearance; a metamerically segmented body covered by slightly sclerotized cuticle, and paired, unjointed lobopodal legs. Antennacanthopodia is also featured by a pair of frontal antennae, potential ocellus-like lateral visual organs, second antennae, a straight, voluminous midgut, diminutive spines arrayed on the leg and the trunk, well-developed leg musculature, highly sclerotized terminal leg pads, and presumptively a pair of posteriormost appendicules. This new taxon, with innovative characters (autapomorphies), furthers our understanding of early lobopodian diversification. Antennacanthopodia is considered closely allied to extant Onychophora based on considerable anatomical similarities. Taken together its “two-segmented” cephalization and appendage-bearing “ocular segment”, this new form may shed some new light on the arthropod groundplan.

@article{doi10166609147r21,
    author = "Ou, Qiang and Liu, Jianni and Shu, Degan and Han, Jian and Zhang, Zhifei and Wan, Xiaoqiao and Lei, Qianping",
    title = "A rare onychophoran-like lobopodian from the Lower Cambrian Chengjiang Lagerstätte, southwestern China, and its phylogenetic implications",
    year = "2011",
    journal = "Journal of Paleontology",
    abstract = "Lobopodians, which diversified and flourished in the Cambrian seas, have long drawn much attention in that not only their extant close relatives, onychophorans and tardigrades, but euarthropods (Chelicerata, Myriapoda, Crustacea, and Hexapoda) may have been deeply rooted in stem-group lobopodians. Antennacanthopodia gracilis new genus and species is described and interpreted here as an “unarmoured” lobopodian from the Chengjiang fossil Lagerstätte (Early Cambrian, —520 Ma), Yunnan, southwestern China. This animal shares with other known Cambrian lobopodians such plesiomorphies (primitive characters) as onychophoran-like overall appearance; a metamerically segmented body covered by slightly sclerotized cuticle, and paired, unjointed lobopodal legs. Antennacanthopodia is also featured by a pair of frontal antennae, potential ocellus-like lateral visual organs, second antennae, a straight, voluminous midgut, diminutive spines arrayed on the leg and the trunk, well-developed leg musculature, highly sclerotized terminal leg pads, and presumptively a pair of posteriormost appendicules. This new taxon, with innovative characters (autapomorphies), furthers our understanding of early lobopodian diversification. Antennacanthopodia is considered closely allied to extant Onychophora based on considerable anatomical similarities. Taken together its “two-segmented” cephalization and appendage-bearing “ocular segment”, this new form may shed some new light on the arthropod groundplan.",
    url = "https://doi.org/10.1666/09-147r2.1",
    doi = "10.1666/09-147r2.1",
    openalex = "W1898259368",
    references = "doi101007s0042700600854, doi10103835106514, doi101038387489a0, doi101038417271a, doi10103846965, doi101038nature06614, doi1011301052517320010110004ehgatg20co2, doi101130g206401, doi1012060003008220023610001fcafmb20co2, doi1023073515467"
}

@article{doi101038nature11495,
    author = "Ma, Xiaoya and Hou, Xianguang and Edgecombe, Gregory D. and Strausfeld, Nicholas J.",
    title = "Complex brain and optic lobes in an early Cambrian arthropod",
    year = "2012",
    journal = "Nature",
    url = "https://doi.org/10.1038/nature11495",
    doi = "10.1038/nature11495",
    openalex = "W2041132847",
    references = "doi101016jasd200501005, doi101038nature10689, doi101073pnas1111784109, doi10108011035890809452772"
}

Cambrian lobopodians are important for understanding the evolution of arthropods, but despite their soft-bodied preservation, the organization of the cephalic region remains obscure. Here we describe new material of the early Cambrian lobopodian Onychodictyon ferox from southern China, which reveals hitherto unknown head structures. These include a proboscis with a terminal mouth, an anterior arcuate sclerite, a pair of ocellus-like eyes and branched, antenniform appendages associated with this ocular segment. These findings, combined with a comparison with other lobopodians, suggest that the head of the last common ancestor of fossil lobopodians and extant panarthropods comprized a single ocular segment with a proboscis and terminal mouth. The lack of specialized mouthparts in O. ferox and the involvement of non-homologous mouthparts in onychophorans, tardigrades and arthropods argue against a common origin of definitive mouth openings among panarthropods, whereas the embryonic stomodaeum might well be homologous at least in Onychophora and Arthropoda.

@article{doi101038ncomms2272,
    author = "Ou, Qiang and Shu, Degan and Mayer, Georg",
    title = "Cambrian lobopodians and extant onychophorans provide new insights into early cephalization in Panarthropoda",
    year = "2012",
    journal = "Nature Communications",
    abstract = "Cambrian lobopodians are important for understanding the evolution of arthropods, but despite their soft-bodied preservation, the organization of the cephalic region remains obscure. Here we describe new material of the early Cambrian lobopodian Onychodictyon ferox from southern China, which reveals hitherto unknown head structures. These include a proboscis with a terminal mouth, an anterior arcuate sclerite, a pair of ocellus-like eyes and branched, antenniform appendages associated with this ocular segment. These findings, combined with a comparison with other lobopodians, suggest that the head of the last common ancestor of fossil lobopodians and extant panarthropods comprized a single ocular segment with a proboscis and terminal mouth. The lack of specialized mouthparts in O. ferox and the involvement of non-homologous mouthparts in onychophorans, tardigrades and arthropods argue against a common origin of definitive mouth openings among panarthropods, whereas the embryonic stomodaeum might well be homologous at least in Onychophora and Arthropoda.",
    url = "https://doi.org/10.1038/ncomms2272",
    doi = "10.1038/ncomms2272",
    openalex = "W2106623073",
    references = "doi10166609147r21, openalexw2185676932"
}

Extant arthropods are diverse and ubiquitous, forming a major constituent of most modern ecosystems. Evidence from early Palaeozoic Konservat Lagerstätten indicates that this has been the case since the Cambrian. Despite this, the details of arthropod origins remain obscure, although most hypotheses regard the first arthropods as benthic predators or scavengers such as the fuxianhuiids or megacheirans ('great-appendage' arthropods). Here, we describe a new arthropod from the Tulip Beds locality of the Burgess Shale Formation (Cambrian, series 3, stage 5) that possesses a weakly sclerotized thorax with filamentous appendages, encased in a bivalved carapace, and a strongly sclerotized, elongate abdomen and telson. A cladistic analysis resolved this taxon as the basal-most member of a paraphyletic grade of nekto-benthic forms with bivalved carapaces. This grade occurs at the base of Arthropoda (panarthropods with arthropodized trunk limbs) and suggests that arthrodization (sclerotization and jointing of the exoskeleton) evolved to facilitate swimming. Predatory and fully benthic habits evolved later in the euarthropod stem-lineage and are plesiomorphically retained in pycnogonids (sea spiders) and euchelicerates (horseshoe crabs and arachnids).

@article{doi101098rspb20121958,
    author = "Legg, David and Sutton, Mark D. and Edgecombe, Gregory D. and Caron, Jean‐Bernard",
    title = "Cambrian bivalved arthropod reveals origin of arthrodization",
    year = "2012",
    journal = "Proceedings of the Royal Society B Biological Sciences",
    abstract = "Extant arthropods are diverse and ubiquitous, forming a major constituent of most modern ecosystems. Evidence from early Palaeozoic Konservat Lagerstätten indicates that this has been the case since the Cambrian. Despite this, the details of arthropod origins remain obscure, although most hypotheses regard the first arthropods as benthic predators or scavengers such as the fuxianhuiids or megacheirans ('great-appendage' arthropods). Here, we describe a new arthropod from the Tulip Beds locality of the Burgess Shale Formation (Cambrian, series 3, stage 5) that possesses a weakly sclerotized thorax with filamentous appendages, encased in a bivalved carapace, and a strongly sclerotized, elongate abdomen and telson. A cladistic analysis resolved this taxon as the basal-most member of a paraphyletic grade of nekto-benthic forms with bivalved carapaces. This grade occurs at the base of Arthropoda (panarthropods with arthropodized trunk limbs) and suggests that arthrodization (sclerotization and jointing of the exoskeleton) evolved to facilitate swimming. Predatory and fully benthic habits evolved later in the euarthropod stem-lineage and are plesiomorphically retained in pycnogonids (sea spiders) and euchelicerates (horseshoe crabs and arachnids).",
    url = "https://doi.org/10.1098/rspb.2012.1958",
    doi = "10.1098/rspb.2012.1958",
    openalex = "W2128120004",
    references = "doi101038417271a, doi10108011035890809452772, doi101098rspb20100590, doi101098rstb19810007, doi101111j109600311993tb00209x, doi101111j109600311999tb00277x, doi101111j109600311999tb00278x, doi101111j10960031200800217x, doi101371journalpone0029233, doi101371journalpone0035495, doi101826182003769311997, doi1023073515467, doi105860choice416546"
}

BACKGROUND: Leanchoilia superlata is one of the best known arthropods from the middle Cambrian Burgess Shale of British Columbia. Here we re-describe the morphology of L. superlata and discuss its possible autecology. The re-description follows a standardized scheme, the descriptive matrix approach, designed to provide a template for descriptions of other megacheiran species. RESULTS: Our findings differ in several respects from previous interpretations. Examples include a more slender body; a possible hypostome; a small specialised second appendage, bringing the number of pairs of head appendages to four; a further sub-division of the great appendage, making it more similar to that of other megacheirans; and a complex joint of the exopod reflecting the arthropod's swimming capabilities. CONCLUSIONS: Different aspects of the morphology, for example, the morphology of the great appendage and the presence of a basipod with strong median armature on the biramous appendages indicate that L. superlata was an active and agile necto-benthic predator (not a scavenger or deposit feeder as previously interpreted).

@article{doi1011861471214812162,
    author = "Haug, Joachim T. and Briggs, Derek E. G. and Haug, Carolin",
    title = "Morphology and function in the Cambrian Burgess Shale megacheiran arthropod Leanchoilia superlata and the application of a descriptive matrix",
    year = "2012",
    journal = "BMC Evolutionary Biology",
    abstract = "BACKGROUND: Leanchoilia superlata is one of the best known arthropods from the middle Cambrian Burgess Shale of British Columbia. Here we re-describe the morphology of L. superlata and discuss its possible autecology. The re-description follows a standardized scheme, the descriptive matrix approach, designed to provide a template for descriptions of other megacheiran species. RESULTS: Our findings differ in several respects from previous interpretations. Examples include a more slender body; a possible hypostome; a small specialised second appendage, bringing the number of pairs of head appendages to four; a further sub-division of the great appendage, making it more similar to that of other megacheirans; and a complex joint of the exopod reflecting the arthropod's swimming capabilities. CONCLUSIONS: Different aspects of the morphology, for example, the morphology of the great appendage and the presence of a basipod with strong median armature on the biramous appendages indicate that L. superlata was an active and agile necto-benthic predator (not a scavenger or deposit feeder as previously interpreted).",
    url = "https://doi.org/10.1186/1471-2148-12-162",
    doi = "10.1186/1471-2148-12-162",
    openalex = "W2039358654",
    references = "doi101016jasd200501005, doi101017s009483730001263x, doi101046j14390469200100164x, doi10108000241160410004764, doi10108011035899509546213, doi101111j10960031200900278x, doi101111j14754983200700649x, doi101126science1169514, doi1016660094837320020280155lgatio20co2, doi101826182000751171987, doi101826182003769311997, doi1023071219595, doi104202app20100080"
}

@article{doi101016jgr201306002,
    author = "Kikumoto, Ryohei and Tahata, Miyuki and Nishizawa, Manabu and Sawaki, Yusuke and Maruyama, Shigenori and Shu, Degan and Han, Jian and Komiya, Tsuyoshi and Takai, Ken and Ueno, Yuichiro",
    title = "Nitrogen isotope chemostratigraphy of the Ediacaran and Early Cambrian platform sequence at Three Gorges, South China",
    year = "2013",
    journal = "Gondwana Research",
    url = "https://doi.org/10.1016/j.gr.2013.06.002",
    doi = "10.1016/j.gr.2013.06.002",
    openalex = "W2067360098",
    references = "doi101016jgr200708004, doi101111j14724669200700125x"
}

A new arthropod, Kootenichela deppi n. gen. n. sp., is described from the Stanley Glacier exposure of the middle Cambrian (Series 3, Stage 5) Stephen Formation in Kootenay National Park (British Columbia, Canada). This taxon possesses a number of primitive arthropod features such as an elongate, homonomous trunk (consisting of at least 29 segments), poorly sclerotised trunk appendages, and large pedunculate eyes associated with an anterior (ocular) sclerite. The cephalon encompasses a possible antenna-like appendage and enlarged raptorial appendages with a bipartite peduncle and three spinose distal podomeres, indicative of megacheiran (“great-appendage” arthropod) affinities. The relationships of megacheirans are controversial, with them generally considered as either stem-euarthropods or a paraphyletic stem-lineage of chelicerates. An extensive cladistic analysis resolved Kootenichela as sister-taxon to the enigmatic Worthenella cambria from the middle Cambrian (Series 3, Stage 5), Burgess Shale Formation in Yoho National Park (British Columbia), which is herein reinterpreted as a megacheiran arthropod. Based on their sister-group relationship, both taxa were placed in the new family Kootenichelidae, to which Pseudoiulia from the Chengjiang biota is also tentatively assigned. All of these taxa possess an elongate, multi-segmented body and subtriangular exopods. This family occupies a basal position within a paraphyletic Megacheira, the immediate outgroup of Euarthropoda (crown-group arthropods). The resultant topology indicates that analyses that have resolved megacheirans as stem-chelicerates have done so because they have rooted on inappropriate taxa, e.g., trilobitomorphs and marrellomorphs.

@article{doi101666121121,
    author = "Legg, David",
    title = "Multi-Segmented Arthropods from the Middle Cambrian of British Columbia (Canada)",
    year = "2013",
    journal = "Journal of Paleontology",
    abstract = "A new arthropod, Kootenichela deppi n. gen. n. sp., is described from the Stanley Glacier exposure of the middle Cambrian (Series 3, Stage 5) Stephen Formation in Kootenay National Park (British Columbia, Canada). This taxon possesses a number of primitive arthropod features such as an elongate, homonomous trunk (consisting of at least 29 segments), poorly sclerotised trunk appendages, and large pedunculate eyes associated with an anterior (ocular) sclerite. The cephalon encompasses a possible antenna-like appendage and enlarged raptorial appendages with a bipartite peduncle and three spinose distal podomeres, indicative of megacheiran (“great-appendage” arthropod) affinities. The relationships of megacheirans are controversial, with them generally considered as either stem-euarthropods or a paraphyletic stem-lineage of chelicerates. An extensive cladistic analysis resolved Kootenichela as sister-taxon to the enigmatic Worthenella cambria from the middle Cambrian (Series 3, Stage 5), Burgess Shale Formation in Yoho National Park (British Columbia), which is herein reinterpreted as a megacheiran arthropod. Based on their sister-group relationship, both taxa were placed in the new family Kootenichelidae, to which Pseudoiulia from the Chengjiang biota is also tentatively assigned. All of these taxa possess an elongate, multi-segmented body and subtriangular exopods. This family occupies a basal position within a paraphyletic Megacheira, the immediate outgroup of Euarthropoda (crown-group arthropods). The resultant topology indicates that analyses that have resolved megacheirans as stem-chelicerates have done so because they have rooted on inappropriate taxa, e.g., trilobitomorphs and marrellomorphs.",
    url = "https://doi.org/10.1666/12-112.1",
    doi = "10.1666/12-112.1",
    openalex = "W2098376903",
    references = "doi101016s0748300703000604, doi101038417271a, doi101111j109600311999tb00277x, doi101111j109600311999tb00278x, doi101111j109600312003tb00376x, doi101111j10960031200800209x, doi101111j10960031200800217x, doi101826182003769311997, doi105860choice416546, openalexw2043379280, openalexw650377807"
}

@article{doi101007s114340140419y,
    author = "Zeng, Han and Zhao, Fangchen and Yin, Zongjun and Li, Guoxiang and Zhu, Maoyan",
    title = "A Chengjiang-type fossil assemblage from the Hongjingshao Formation (Cambrian Stage 3) at Chenggong, Kunming, Yunnan",
    year = "2014",
    journal = "Chinese Science Bulletin",
    url = "https://doi.org/10.1007/s11434-014-0419-y",
    doi = "10.1007/s11434-014-0419-y",
    openalex = "W1974137355",
    references = "doi101016jpalaeo200306001, doi101016jpalwor200610016, doi101038377720a0, doi101038417271a, doi10103846965, doi101038nature11874, doi101144jgs1582211, doi105860choice416546, doi105860choice510294, openalexw2597139979, openalexw650377807"
}

@article{doi101016jprecamres201403002,
    author = "Feng, Lianjun and Li, Chao and Huang, Jing and Chang, Huajin and Chu, Xuelei",
    title = "A sulfate control on marine mid-depth euxinia on the early Cambrian (ca. 529–521Ma) Yangtze platform, South China",
    year = "2014",
    journal = "Precambrian Research",
    url = "https://doi.org/10.1016/j.precamres.2014.03.002",
    doi = "10.1016/j.precamres.2014.03.002",
    openalex = "W2064173032",
    references = "doi101016jpalaeo200306001"
}

@article{doi101038ncomms4560,
    author = "Ma, Xiaoya and Cong, Peiyun and Hou, Xianguang and Edgecombe, Gregory D. and Strausfeld, Nicholas J.",
    title = "An exceptionally preserved arthropod cardiovascular system from the early Cambrian",
    year = "2014",
    journal = "Nature Communications",
    url = "https://doi.org/10.1038/ncomms4560",
    doi = "10.1038/ncomms4560",
    openalex = "W1997999149",
    references = "doi1010079783642361609, doi101016jasd200501005, doi101038417271a, doi101038nature11495, doi101038nature11874, doi101038ncomms3485, doi101073pnas1111784109, doi10108011035890809452772, doi101111j10960031200900278x, doi101139e06012, doi1016660094837320020280155lgatio20co2, doi101826182003769311997, doi102110palo2009p09004r"
}

Abstract Phylogenomics reconstructs an arthropod tree in which a monophyletic A rthropoda splits into P ycnogonida + E uchelicerata and M yriapoda + P ancrustacea. The same chelicerate–mandibulate groups are retrieved with morphological data sets, including those encompassing most taxa known from P alaeozoic K onservat‐ L agerstätten. With respect to the interrelationships of the three extant clades of P anarthropoda, a sister group relationship between O nychophora and A rthropoda is endorsed by transcriptomics and micro RNA s, although this hypothesis forces homoplasy in characters of the segmental ganglia that are shared by tardigrades and arthropods. Cambrian lobopodians, dinocaridids, bivalved arthropods and fuxianhuiids document the successive appearance of characteristic arthropod features in the stem lineage of E uarthropoda (crown‐group arthropods). Molecular dating suggests that arthropods had their origin and initial diversification in the E diacaran, but no convincing palaeontological evidence for P anarthropoda is available until the earliest Cambrian.

@article{doi101111pala12105,
    author = "Edgecombe, Gregory D. and Legg, David",
    title = "Origins and early evolution of arthropods",
    year = "2014",
    journal = "Palaeontology",
    abstract = "Abstract Phylogenomics reconstructs an arthropod tree in which a monophyletic A rthropoda splits into P ycnogonida + E uchelicerata and M yriapoda + P ancrustacea. The same chelicerate–mandibulate groups are retrieved with morphological data sets, including those encompassing most taxa known from P alaeozoic K onservat‐ L agerstätten. With respect to the interrelationships of the three extant clades of P anarthropoda, a sister group relationship between O nychophora and A rthropoda is endorsed by transcriptomics and micro RNA s, although this hypothesis forces homoplasy in characters of the segmental ganglia that are shared by tardigrades and arthropods. Cambrian lobopodians, dinocaridids, bivalved arthropods and fuxianhuiids document the successive appearance of characteristic arthropod features in the stem lineage of E uarthropoda (crown‐group arthropods). Molecular dating suggests that arthropods had their origin and initial diversification in the E diacaran, but no convincing palaeontological evidence for P anarthropoda is available until the earliest Cambrian.",
    url = "https://doi.org/10.1111/pala.12105",
    doi = "10.1111/pala.12105",
    openalex = "W2046626368",
    references = "doi101038nature11874, doi101038nature12520, doi101080147720192012732723, doi101098rspb20121958, doi101111j14754983201101124x, doi101371journalpone0059090, doi10166609147r21, doi101666121121, doi104202app20100080, openalexw2185676932"
}

@article{doi101016jasd201507005,
    author = "Strausfeld, Nicholas J. and Ma, Xiaoya and Edgecombe, Gregory D. and Fortey, Richard A. and Land, Michael F. and Liu, Yu and Cong, Peiyun and Hou, Xianguang",
    title = "Arthropod eyes: The early Cambrian fossil record and divergent evolution of visual systems",
    year = "2015",
    journal = "Arthropod Structure \& Development",
    url = "https://doi.org/10.1016/j.asd.2015.07.005",
    doi = "10.1016/j.asd.2015.07.005",
    openalex = "W1446681948",
    references = "doi101016016895259090017z, doi101016jcub200507034, doi101016jcub201301026, doi101038nature12520, doi101038nature14256, doi101038srep02120, doi101093molbevmsq130, doi101098rspb19940048, doi101098rspb20090361, doi101111j10960031201200413x, doi10118617429994101, doi10118617429994729, doi101371journalpbio1002005, doi101666060821, doi101666121121, doi101666pleo050701, doi105860choice416546, openalexw650377807"
}

We describe Collinsium ciliosum from the early Cambrian Xiaoshiba Lagerstätte in South China, an armored lobopodian with a remarkable degree of limb differentiation including a pair of antenna-like appendages, six pairs of elongate setiferous limbs for suspension feeding, and nine pairs of clawed annulated legs with an anchoring function. Collinsium belongs to a highly derived clade of lobopodians within stem group Onychophora, distinguished by a substantial dorsal armature of supernumerary and biomineralized spines (Family Luolishaniidae). As demonstrated here, luolishaniids display the highest degree of limb specialization among Paleozoic lobopodians, constitute more than one-third of the overall morphological disparity of stem group Onychophora, and are substantially more disparate than crown group representatives. Despite having higher disparity and appendage complexity than other lobopodians and extant velvet worms, the specialized mode of life embodied by luolishaniids became extinct during the Early Paleozoic. Collinsium and other superarmored lobopodians exploited a unique paleoecological niche during the Cambrian explosion.

@article{doi101073pnas1505596112,
    author = "Yang, Jie and Ortega‐Hernández, Javier and Gerber, Sylvain and Butterfield, Nicholas J. and Hou, Jin‐bo and Lan, Tian and Zhang, Xiguang",
    title = "A superarmored lobopodian from the Cambrian of China and early disparity in the evolution of Onychophora",
    year = "2015",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "We describe Collinsium ciliosum from the early Cambrian Xiaoshiba Lagerstätte in South China, an armored lobopodian with a remarkable degree of limb differentiation including a pair of antenna-like appendages, six pairs of elongate setiferous limbs for suspension feeding, and nine pairs of clawed annulated legs with an anchoring function. Collinsium belongs to a highly derived clade of lobopodians within stem group Onychophora, distinguished by a substantial dorsal armature of supernumerary and biomineralized spines (Family Luolishaniidae). As demonstrated here, luolishaniids display the highest degree of limb specialization among Paleozoic lobopodians, constitute more than one-third of the overall morphological disparity of stem group Onychophora, and are substantially more disparate than crown group representatives. Despite having higher disparity and appendage complexity than other lobopodians and extant velvet worms, the specialized mode of life embodied by luolishaniids became extinct during the Early Paleozoic. Collinsium and other superarmored lobopodians exploited a unique paleoecological niche during the Cambrian explosion.",
    url = "https://doi.org/10.1073/pnas.1505596112",
    doi = "10.1073/pnas.1505596112",
    openalex = "W1849166755",
    references = "doi101007s114340140419y, doi101038nature11874, doi101111brv12168, doi103140bullgeosci1280"
}

Abstract The Guole biota contains common shelly fossils and some exceptionally well‐preserved soft‐bodied fossils. Stratigraphically, it is located in the mudstones and siltstones of the Sandu Formation near Guole Town, Jingxi County, Guangxi, South China. It is the first Furongian (late Cambrian) Burgess Shale‐type biota found in the world, thereby filling the gap between middle Cambrian and Lower Ordovician Burgess Shale‐type Lagerstätten. Preliminary studies suggest that the Guole biota includes approximately seven metazoan groups as well as algae. These will provide important new evolutionary and ecological information.

@article{doi1011111755672412640,
    author = "Xuejian, ZHU and Peng, Shanchi and Zamora, Samuel and Lefèbvre, Bertrand and Chen, Guiying",
    title = "Furongian (upper Cambrian) Guole Konservat‐Lagerstätte from South China",
    year = "2016",
    journal = "Acta Geologica Sinica - English Edition",
    abstract = "Abstract The Guole biota contains common shelly fossils and some exceptionally well‐preserved soft‐bodied fossils. Stratigraphically, it is located in the mudstones and siltstones of the Sandu Formation near Guole Town, Jingxi County, Guangxi, South China. It is the first Furongian (late Cambrian) Burgess Shale‐type biota found in the world, thereby filling the gap between middle Cambrian and Lower Ordovician Burgess Shale‐type Lagerstätten. Preliminary studies suggest that the Guole biota includes approximately seven metazoan groups as well as algae. These will provide important new evolutionary and ecological information.",
    url = "https://doi.org/10.1111/1755-6724.12640",
    doi = "10.1111/1755-6724.12640",
    openalex = "W2292083429",
    references = "doi101007s114340140419y"
}

@book{doi1010029781118896372,
    author = "Hou, Xianguang and Siveter, David J. and Siveter, Derek J. and Aldridge, Richard J. and Cong, Peiyun and Gabbott, Sarah E. and Ma, Xiaoya and Purnell, Mark A. and Williams, Mark",
    title = "The Cambrian Fossils of Chengjiang, China",
    year = "2017",
    url = "https://doi.org/10.1002/9781118896372",
    doi = "10.1002/9781118896372",
    openalex = "W4254217775"
}

Abstract Appendage anatomy contributes crucial data for understanding the evolution and ecology of Euarthropoda. The Palaeozoic trilobites show a great diversity of exoskeletons in the fossil record. However, soft parts, especially appendages, have only been discovered from a few trilobite species. Here we report extraordinarily preserved appendages in the trilobite species Hongshiyanaspis yiliangensis Zhang & Lin in Zhang et al. 1980 (Redlichiida, Metadoxididae) from a single mudstone layer of the Xiazhuang fossil assemblage within the Hongjingshao Formation (Cambrian Series 2, Stage 3) near Kunming, Yunnan, SW China. The appendages exhibit the common architecture revealed by other trilobites and artiopods by consisting of a pair of uniramous antennae followed by a series of paired homonomous biramous limbs. The antennae in holaspid individuals comprise up to 27 spinous podomeres and their ontogeny occurs by lengthening of the podomeres. The post-antennal biramous limbs are similar to those in other polymerid trilobites and artiopods by having a single-segmented protopodite and an endopodite comprising seven segments, but possess a unique wide tripartite exopodite with long setae. Sophisticated appendage anatomy, including the body–limb junction, fine setae, putative muscle bundles and duct-type tissues, are also revealed. Appendages of trilobites, artiopods and other upper stem-group euarthropods are compared and summarized. The H. yiliangensis appendages highlight the high morphological disparity of exopodites and the conservativeness of endopodites in trilobites and artiopods. This morphological pattern, together with similar body patterning seen in crustaceans but not in chelicerates, supports the mandibulate affinities of trilobites and at least some artiopods.

@article{doi101017s0016756817000279,
    author = "Zeng, Han and Zhao, Fangchen and Yin, Zongjun and Zhu, Maoyan",
    title = "Appendages of an early Cambrian metadoxidid trilobite from Yunnan, SW China support mandibulate affinities of trilobites and artiopods",
    year = "2017",
    journal = "Geological Magazine",
    abstract = "Abstract Appendage anatomy contributes crucial data for understanding the evolution and ecology of Euarthropoda. The Palaeozoic trilobites show a great diversity of exoskeletons in the fossil record. However, soft parts, especially appendages, have only been discovered from a few trilobite species. Here we report extraordinarily preserved appendages in the trilobite species Hongshiyanaspis yiliangensis Zhang \& Lin in Zhang et al. 1980 (Redlichiida, Metadoxididae) from a single mudstone layer of the Xiazhuang fossil assemblage within the Hongjingshao Formation (Cambrian Series 2, Stage 3) near Kunming, Yunnan, SW China. The appendages exhibit the common architecture revealed by other trilobites and artiopods by consisting of a pair of uniramous antennae followed by a series of paired homonomous biramous limbs. The antennae in holaspid individuals comprise up to 27 spinous podomeres and their ontogeny occurs by lengthening of the podomeres. The post-antennal biramous limbs are similar to those in other polymerid trilobites and artiopods by having a single-segmented protopodite and an endopodite comprising seven segments, but possess a unique wide tripartite exopodite with long setae. Sophisticated appendage anatomy, including the body–limb junction, fine setae, putative muscle bundles and duct-type tissues, are also revealed. Appendages of trilobites, artiopods and other upper stem-group euarthropods are compared and summarized. The H. yiliangensis appendages highlight the high morphological disparity of exopodites and the conservativeness of endopodites in trilobites and artiopods. This morphological pattern, together with similar body patterning seen in crustaceans but not in chelicerates, supports the mandibulate affinities of trilobites and at least some artiopods.",
    url = "https://doi.org/10.1017/s0016756817000279",
    doi = "10.1017/s0016756817000279",
    openalex = "W2604493875",
    references = "doi101007s114340140419y"
}

Cambrian marine ecosystems were dominated by arthropods, and more specifically artiopods. Aglaspidids represent an atypical group amongst them, not the least because they evolved and rapidly diversified during the late Cambrian, a time interval between the two diversification events of the Early Palaeozoic. Recent phylogenetic analyses have retrieved aglaspidids within the Vicissicaudata, a potentially important, but difficult to define clade of artiopods. Here we describe a new aglaspidid from the Furongian Guole Konservat-Lagerstätte of South China. This taxon displays a pretelsonic segment bearing non-walking appendages, features as-yet known in all vicissicaudatans, but aglaspidids. A new comprehensive phylogenetic analysis provides strong support for the legitimacy of a monophyletic clade Vicissicaudata, and demonstrates the pertinence of new characters to define Aglaspidida. It also motivates important changes to the systematics of the phylum, including the elevation of Artiopoda to the rank of subphylum, and the establishment of a new superclass Vicissicaudata and a new aglaspidid family Tremaglaspididae. Two diversification pulses can be recognized in the early history of artiopods - one in the early Cambrian (trilobitomorphs) and the other in the late Cambrian (vicissicaudatans). The discrepancy between this pattern and that traditionally depicted for marine invertebrates in the Early Palaeozoic is discussed.

@article{doi101038s41598017116105,
    author = "Lerosey‐Aubril, Rudy and Zhu, Xuejian and Ortega‐Hernández, Javier",
    title = "The Vicissicaudata revisited – insights from a new aglaspidid arthropod with caudal appendages from the Furongian of China",
    year = "2017",
    journal = "Scientific Reports",
    abstract = "Cambrian marine ecosystems were dominated by arthropods, and more specifically artiopods. Aglaspidids represent an atypical group amongst them, not the least because they evolved and rapidly diversified during the late Cambrian, a time interval between the two diversification events of the Early Palaeozoic. Recent phylogenetic analyses have retrieved aglaspidids within the Vicissicaudata, a potentially important, but difficult to define clade of artiopods. Here we describe a new aglaspidid from the Furongian Guole Konservat-Lagerstätte of South China. This taxon displays a pretelsonic segment bearing non-walking appendages, features as-yet known in all vicissicaudatans, but aglaspidids. A new comprehensive phylogenetic analysis provides strong support for the legitimacy of a monophyletic clade Vicissicaudata, and demonstrates the pertinence of new characters to define Aglaspidida. It also motivates important changes to the systematics of the phylum, including the elevation of Artiopoda to the rank of subphylum, and the establishment of a new superclass Vicissicaudata and a new aglaspidid family Tremaglaspididae. Two diversification pulses can be recognized in the early history of artiopods - one in the early Cambrian (trilobitomorphs) and the other in the late Cambrian (vicissicaudatans). The discrepancy between this pattern and that traditionally depicted for marine invertebrates in the Early Palaeozoic is discussed.",
    url = "https://doi.org/10.1038/s41598-017-11610-5",
    doi = "10.1038/s41598-017-11610-5",
    openalex = "W2750970422",
    references = "doi10108003115510508619300"
}

Exceptionally preserved fossils, such as those from Cambrian Burgess Shale-type fossil-Lagerstätten are critical because of their unique contributions to knowledge of the phylogenetic radiation and palaeoecological expansion of metazoans during the Cambrian explosion. Critically, these deposits provide information that is usually unobtainable from shelly and skeletonized fossils alone. The Guanshan Biota (Cambrian Series 2, Stage 4) in the Yunnan Province of South China, has produced abundant and diverse, exquisitely preserved fossils that often retain soft tissues and organs. To date, most fossils from the Guanshan Biota have been collected from localities such as Gaoloufang and Gangtoucun, which have become inaccessible due to new urban expansions and constructions of residential buildings. Here we present the first report of soft bodied fossils from a new section at Kanfuqing, close to the Wulongqing village in Malong County, approximately 3 km east of the Wulongqing Formation stratotype section. Fossils retain soft morphology, and include brachiopods with delicate marginal setae, priapulids with well-preserved sclerites and vetulicolians with entire sections of body. In addition, this fauna includes rare occurrences of trilobites preserved with soft tissues replicated as pyrite pseudomorphs after weathering. This discovery represents an important palaeogeographical extension of soft-bodied fossils of the Guanshan fauna to the east of the Xiaojiang Fault (related to Tsinning tectonic movements ca. 700 Ma). The fauna from the new Kanfuqing section is similar to that reported from the Wulongqing Formation west of the Xiaojiang Fault, and thus has significant implications for early Cambrian palaeogeography, faunal successions and palaeoenvironments of eastern Yunnan. Keywords: Guanshan Biota, Early Cambrian, Xiaojiang Fault, Eastern Yunnan, Palaeoenvironment, Palaeogeography

@article{doi101016jgsf201809010,
    author = "Chen, Feiyang and Zhang, Zhifei and Betts, Marissa J. and Zhang, Zhiliang and Liu, Fan",
    title = "First report on Guanshan Biota (Cambrian Stage 4) at the stratotype area of Wulongqing Formation in Malong County, Eastern Yunnan, China",
    year = "2018",
    journal = "Geoscience Frontiers",
    abstract = "Exceptionally preserved fossils, such as those from Cambrian Burgess Shale-type fossil-Lagerstätten are critical because of their unique contributions to knowledge of the phylogenetic radiation and palaeoecological expansion of metazoans during the Cambrian explosion. Critically, these deposits provide information that is usually unobtainable from shelly and skeletonized fossils alone. The Guanshan Biota (Cambrian Series 2, Stage 4) in the Yunnan Province of South China, has produced abundant and diverse, exquisitely preserved fossils that often retain soft tissues and organs. To date, most fossils from the Guanshan Biota have been collected from localities such as Gaoloufang and Gangtoucun, which have become inaccessible due to new urban expansions and constructions of residential buildings. Here we present the first report of soft bodied fossils from a new section at Kanfuqing, close to the Wulongqing village in Malong County, approximately 3 km east of the Wulongqing Formation stratotype section. Fossils retain soft morphology, and include brachiopods with delicate marginal setae, priapulids with well-preserved sclerites and vetulicolians with entire sections of body. In addition, this fauna includes rare occurrences of trilobites preserved with soft tissues replicated as pyrite pseudomorphs after weathering. This discovery represents an important palaeogeographical extension of soft-bodied fossils of the Guanshan fauna to the east of the Xiaojiang Fault (related to Tsinning tectonic movements ca. 700 Ma). The fauna from the new Kanfuqing section is similar to that reported from the Wulongqing Formation west of the Xiaojiang Fault, and thus has significant implications for early Cambrian palaeogeography, faunal successions and palaeoenvironments of eastern Yunnan. Keywords: Guanshan Biota, Early Cambrian, Xiaojiang Fault, Eastern Yunnan, Palaeoenvironment, Palaeogeography",
    url = "https://doi.org/10.1016/j.gsf.2018.09.010",
    doi = "10.1016/j.gsf.2018.09.010",
    openalex = "W2899533842",
    references = "doi101007s114340140419y, doi101016jearscirev201510015, doi101038srep14810, doi103140bullgeosci1269"
}

Euarthropoda is one of the best-preserved fossil animal groups and has been the most diverse animal phylum for over 500 million years. Fossil Konservat-Lagerstätten, such as Burgess Shale-type deposits (BSTs), show the evolution of the euarthropod stem lineage during the Cambrian from 518 million years ago (Ma). The stem lineage includes nonbiomineralized groups, such as Radiodonta (e.g., Anomalocaris) that provide insight into the step-by-step construction of euarthropod morphology, including the exoskeleton, biramous limbs, segmentation, and cephalic structures. Trilobites are crown group euarthropods that appear in the fossil record at 521 Ma, before the stem lineage fossils, implying a ghost lineage that needs to be constrained. These constraints come from the trace fossil record, which show the first evidence for total group Euarthropoda (e.g., Cruziana, Rusophycus) at around 537 Ma. A deep Precambrian root to the euarthropod evolutionary lineage is disproven by a comparison of Ediacaran and Cambrian lagerstätten. BSTs from the latest Ediacaran Period (e.g., Miaohe biota, 550 Ma) are abundantly fossiliferous with algae but completely lack animals, which are also missing from other Ediacaran windows, such as phosphate deposits (e.g., Doushantuo, 560 Ma). This constrains the appearance of the euarthropod stem lineage to no older than 550 Ma. While each of the major types of fossil evidence (BSTs, trace fossils, and biomineralized preservation) have their limitations and are incomplete in different ways, when taken together they allow a coherent picture to emerge of the origin and subsequent radiation of total group Euarthropoda during the Cambrian.

@article{doi101073pnas1719962115,
    author = "Daley, Allison C. and Antcliffe, Jonathan B. and Drage, Harriet B. and Pates, Stephen",
    title = "Early fossil record of Euarthropoda and the Cambrian Explosion",
    year = "2018",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Euarthropoda is one of the best-preserved fossil animal groups and has been the most diverse animal phylum for over 500 million years. Fossil Konservat-Lagerstätten, such as Burgess Shale-type deposits (BSTs), show the evolution of the euarthropod stem lineage during the Cambrian from 518 million years ago (Ma). The stem lineage includes nonbiomineralized groups, such as Radiodonta (e.g., Anomalocaris) that provide insight into the step-by-step construction of euarthropod morphology, including the exoskeleton, biramous limbs, segmentation, and cephalic structures. Trilobites are crown group euarthropods that appear in the fossil record at 521 Ma, before the stem lineage fossils, implying a ghost lineage that needs to be constrained. These constraints come from the trace fossil record, which show the first evidence for total group Euarthropoda (e.g., Cruziana, Rusophycus) at around 537 Ma. A deep Precambrian root to the euarthropod evolutionary lineage is disproven by a comparison of Ediacaran and Cambrian lagerstätten. BSTs from the latest Ediacaran Period (e.g., Miaohe biota, 550 Ma) are abundantly fossiliferous with algae but completely lack animals, which are also missing from other Ediacaran windows, such as phosphate deposits (e.g., Doushantuo, 560 Ma). This constrains the appearance of the euarthropod stem lineage to no older than 550 Ma. While each of the major types of fossil evidence (BSTs, trace fossils, and biomineralized preservation) have their limitations and are incomplete in different ways, when taken together they allow a coherent picture to emerge of the origin and subsequent radiation of total group Euarthropoda during the Cambrian.",
    url = "https://doi.org/10.1073/pnas.1719962115",
    doi = "10.1073/pnas.1719962115",
    openalex = "W2803773655",
    references = "doi101016b9780444594259000196, doi101016jcub201509066, doi101016jearscirev201303008, doi101016jearscirev201606008, doi101016jearscirev201707017, doi101016jpalwor200610005, doi101017s000632310000548x, doi101017s1089332600002837, doi101038376053a0, doi101038nature07673, doi101038nature10689, doi101038nature11874, doi101038nature12520, doi101038nature13414, doi101038nature14256, doi101038ncomms3485, doi101073pnas1111784109, doi101098rstb19750033, doi101098rstb20140313, doi101111brv12168, doi101111j10960031201200413x, doi101126science1107765, doi101126science1169514, doi101126science1206375, doi101126science2745287568, doi101144gsjgs14940607, doi101146annurevearth33092203122519, doi101186s1286201710887, doi101666061301, doi10166612056"
}

Sexuality is an integral component of many intimate relationships, and research has consistently demonstrated a positive association between sexual and marital satisfaction. However, the temporal dynamics of this association remain controversial and understudied with rigorous longitudinal dyadic approaches, and empirical efforts examining this association in non-Western samples remain sparse. Based on three annual waves of data from 268 Chinese couples during the early years of marriage, this study tested a cross-lagged, actor-partner interdependence model examining the association between sexual and marital satisfaction. Results indicated that (a) across three waves, husbands' earlier sexual satisfaction predicted their later marital satisfaction, rather than the reverse; (b) from Wave 1 to Wave 2, wives' earlier marital satisfaction predicted their later sexual satisfaction, rather than the reverse, but no association between wives' sexual and marital satisfaction was found from Wave 2 to Wave 3; and (c) four longitudinal indirect associations linking sexual and marital satisfaction were identified, including three actor associations and one partner association. Such findings shed light on the complexity inherent within the dynamic association between sexual and marital satisfaction over the early years of marriage in the Chinese cultural context.

@article{doi1010800022449920181463503,
    author = "Cao, Hongjian and Zhou, Nan and Fine, Mark A. and Li, Xiaomin and Fang, Xiaoyi",
    title = "Sexual Satisfaction and Marital Satisfaction During the Early Years of Chinese Marriage: A Three-Wave, Cross-Lagged, Actor–Partner Interdependence Model",
    year = "2018",
    journal = "The Journal of Sex Research",
    abstract = "Sexuality is an integral component of many intimate relationships, and research has consistently demonstrated a positive association between sexual and marital satisfaction. However, the temporal dynamics of this association remain controversial and understudied with rigorous longitudinal dyadic approaches, and empirical efforts examining this association in non-Western samples remain sparse. Based on three annual waves of data from 268 Chinese couples during the early years of marriage, this study tested a cross-lagged, actor-partner interdependence model examining the association between sexual and marital satisfaction. Results indicated that (a) across three waves, husbands' earlier sexual satisfaction predicted their later marital satisfaction, rather than the reverse; (b) from Wave 1 to Wave 2, wives' earlier marital satisfaction predicted their later sexual satisfaction, rather than the reverse, but no association between wives' sexual and marital satisfaction was found from Wave 2 to Wave 3; and (c) four longitudinal indirect associations linking sexual and marital satisfaction were identified, including three actor associations and one partner association. Such findings shed light on the complexity inherent within the dynamic association between sexual and marital satisfaction over the early years of marriage in the Chinese cultural context.",
    url = "https://doi.org/10.1080/00224499.2018.1463503",
    doi = "10.1080/00224499.2018.1463503",
    openalex = "W2802819891",
    references = "doi101525srsp20041163"
}

The Cambrian Chengjiang biota of South China provides compelling fossil evidence for the rapid appearance of metazoan phyla in Earth history (the ‘Cambrian explosion’). However, the timing of the Chengjiang biota is poorly constrained owing to lack of datable rock materials within the Maotianshan Shale that yields the fossils. Here we integrate secondary ion mass spectrometry (SIMS) and chemical ablation isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) U–Pb analyses of detrital zircons from the Maotianshan Shale to provide high-precision geochronological constraint on the Chengjiang biota. The youngest group of SIMS U–Pb detrital zircon dates yields an age peak at 520 Ma. Six zircons from this group are further dated by the CA-ID-TIMS U–Pb technique, but suggesting that they were not formed from a single zircon growth event. Thereby neither the age peak nor the weighted mean age defined by the youngest SIMS U–Pb dates could represent the maximum depositional age of the Maotianshan Shale. Instead, the youngest CA-ID-TIMS U–Pb date, 518.03 ± 0.69/0.71 Ma (2 σ, analytical uncertainty/incorporates U–Pb tracer calibration uncertainty), provides the first robust maximum age of the Chengjiang biota. This new geochronological constraint on the Chengjiang biota indicates that the Cambrian explosion reached its major phase around 518.03 ± 0.69/0.71 Ma, demonstrating a protracted process (>22 myr) for the Cambrian explosion. Supplementary material: SIMS and CA-ID-TIMS zircon U–Pb data are available at https://doi.org/10.6084/m9.figshare.c.4024849

@article{doi101144jgs2017103,
    author = "Yang, Chuan and Li, Xian‐Hua and Zhu, Maoyan and Condon, Daniel J. and Chen, Junyuan",
    title = "Geochronological constraint on the Cambrian Chengjiang biota, South China",
    year = "2018",
    journal = "Journal of the Geological Society",
    abstract = "The Cambrian Chengjiang biota of South China provides compelling fossil evidence for the rapid appearance of metazoan phyla in Earth history (the ‘Cambrian explosion’). However, the timing of the Chengjiang biota is poorly constrained owing to lack of datable rock materials within the Maotianshan Shale that yields the fossils. Here we integrate secondary ion mass spectrometry (SIMS) and chemical ablation isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) U–Pb analyses of detrital zircons from the Maotianshan Shale to provide high-precision geochronological constraint on the Chengjiang biota. The youngest group of SIMS U–Pb detrital zircon dates yields an age peak at 520 Ma. Six zircons from this group are further dated by the CA-ID-TIMS U–Pb technique, but suggesting that they were not formed from a single zircon growth event. Thereby neither the age peak nor the weighted mean age defined by the youngest SIMS U–Pb dates could represent the maximum depositional age of the Maotianshan Shale. Instead, the youngest CA-ID-TIMS U–Pb date, 518.03 ± 0.69/0.71 Ma (2 σ, analytical uncertainty/incorporates U–Pb tracer calibration uncertainty), provides the first robust maximum age of the Chengjiang biota. This new geochronological constraint on the Chengjiang biota indicates that the Cambrian explosion reached its major phase around 518.03 ± 0.69/0.71 Ma, demonstrating a protracted process (>22 myr) for the Cambrian explosion. Supplementary material: SIMS and CA-ID-TIMS zircon U–Pb data are available at https://doi.org/10.6084/m9.figshare.c.4024849",
    url = "https://doi.org/10.1144/jgs2017-103",
    doi = "10.1144/jgs2017-103",
    openalex = "W2793886337",
    references = "doi101016jearscirev201707017, doi101016jgr200708004, doi101016jprecamres201609016"
}

BACKGROUND: Extended parental care is a complex reproductive strategy in which progenitors actively look after their offspring up to - or beyond - the first juvenile stage in order to maximize their fitness. Although the euarthropod fossil record has produced several examples of brood-care, the appearance of extended parental care within this phylum remains poorly constrained given the scarcity of developmental data for Palaeozoic stem-group representatives that would link juvenile and adult forms in an ontogenetic sequence. RESULTS: Here, we describe the post-embryonic growth of Fuxianhuia protensa from the early Cambrian Chengjiang Lagerstätte in South China. Our data demonstrate anamorphic post-embryonic development for F. protensa, in which new tergites were sequentially added from a posterior growth zone, the number of tergites varies from eight to 30. The growth of F. protensa is typified by the alternation between segment addition, followed by the depletion of the anteriormost abdominal segment into the thoracic region. The transformation of abdominal into thoracic tergite is demarcated by the development of laterally tergopleurae, and biramous walking legs. The new ontogeny data leads to the recognition of the rare Chengjiang euarthropod Pisinnocaris subconigera as a junior synonym of Fuxianhuia. Comparisons between different species of Fuxianhuia and with other genera within Fuxianhuiida suggest that heterochrony played a prominent role in the morphological diversification of fuxianhuiids. Functional analogy with the flexible trunk ontogeny of Cambrian and Silurian olenimorphic trilobites suggests an adaptation to sporadic low oxygen conditions in Chengjiang deposits for F. protensa. Finally, understanding the growth of F. protensa allows for the interpretation of an exceptional life assemblage consisting of a sexually mature adult alongside four ontogenetically coeval juveniles, which constitutes the oldest occurrence of extended parental care by prolonged cohabitation in the panarthropod fossil record. CONCLUSIONS: Our findings constitute the most detailed characterization of the post-embryonic development in a soft-bodied upper stem-group euarthropod available to date. The new ontogeny data illuminates the systematics, trunk segmentation and palaeoecology of F. protensa, offers insights on the macroevolutionary processes involved in the diversification of this clade, and contributes towards an improved understanding of complex post-embryonic reproductive ecology in Cambrian euarthropods.

@article{doi101186s1286201812626,
    author = "Fu, Dongjing and Ortega‐Hernández, Javier and Daley, Allison C. and Zhang, Xingliang and Shu, Degan",
    title = "Anamorphic development and extended parental care in a 520 million-year-old stem-group euarthropod from China",
    year = "2018",
    journal = "BMC Evolutionary Biology",
    abstract = "BACKGROUND: Extended parental care is a complex reproductive strategy in which progenitors actively look after their offspring up to - or beyond - the first juvenile stage in order to maximize their fitness. Although the euarthropod fossil record has produced several examples of brood-care, the appearance of extended parental care within this phylum remains poorly constrained given the scarcity of developmental data for Palaeozoic stem-group representatives that would link juvenile and adult forms in an ontogenetic sequence. RESULTS: Here, we describe the post-embryonic growth of Fuxianhuia protensa from the early Cambrian Chengjiang Lagerstätte in South China. Our data demonstrate anamorphic post-embryonic development for F. protensa, in which new tergites were sequentially added from a posterior growth zone, the number of tergites varies from eight to 30. The growth of F. protensa is typified by the alternation between segment addition, followed by the depletion of the anteriormost abdominal segment into the thoracic region. The transformation of abdominal into thoracic tergite is demarcated by the development of laterally tergopleurae, and biramous walking legs. The new ontogeny data leads to the recognition of the rare Chengjiang euarthropod Pisinnocaris subconigera as a junior synonym of Fuxianhuia. Comparisons between different species of Fuxianhuia and with other genera within Fuxianhuiida suggest that heterochrony played a prominent role in the morphological diversification of fuxianhuiids. Functional analogy with the flexible trunk ontogeny of Cambrian and Silurian olenimorphic trilobites suggests an adaptation to sporadic low oxygen conditions in Chengjiang deposits for F. protensa. Finally, understanding the growth of F. protensa allows for the interpretation of an exceptional life assemblage consisting of a sexually mature adult alongside four ontogenetically coeval juveniles, which constitutes the oldest occurrence of extended parental care by prolonged cohabitation in the panarthropod fossil record. CONCLUSIONS: Our findings constitute the most detailed characterization of the post-embryonic development in a soft-bodied upper stem-group euarthropod available to date. The new ontogeny data illuminates the systematics, trunk segmentation and palaeoecology of F. protensa, offers insights on the macroevolutionary processes involved in the diversification of this clade, and contributes towards an improved understanding of complex post-embryonic reproductive ecology in Cambrian euarthropods.",
    url = "https://doi.org/10.1186/s12862-018-1262-6",
    doi = "10.1186/s12862-018-1262-6",
    openalex = "W2952588367",
    references = "doi1010029781118896372, doi101007s114340140419y, doi101016jasd200501005, doi101016jcub201705040, doi101038nature11495, doi101038nmeth2019, doi101111j1469185x200900097x, doi101353book31448, doi10182618200374874199301, doi101826182003769311997, openalexw650377807"
}

The chelicerates are a ubiquitous and speciose group of animals that has a considerable ecological effect on modern terrestrial ecosystems-notably as predators of insects and also, for instance, as decomposers1. The fossil record shows that chelicerates diversified early in the marine ecosystems of the Palaeozoic era, by at least the Ordovician period2. However, the timing of chelicerate origins and the type of body plan that characterized the earliest members of this group have remained controversial. Although megacheirans3-5 have previously been interpreted as chelicerate-like, and habeliidans6 (including Sanctacaris7,8) have been suggested to belong to their immediate stem lineage, evidence for the specialized feeding appendages (chelicerae) that are diagnostic of the chelicerates has been lacking. Here we use exceptionally well-preserved and abundant fossil material from the middle Cambrian Burgess Shale (Marble Canyon, British Columbia, Canada) to show that Mollisonia plenovenatrix sp. nov. possessed robust but short chelicerae that were placed very anteriorly, between the eyes. This suggests that chelicerae evolved a specialized feeding function early on, possibly as a modification of short antennules. The head also encompasses a pair of large compound eyes, followed by three pairs of long, uniramous walking legs and three pairs of stout, gnathobasic masticatory appendages; this configuration links habeliidans with euchelicerates ('true' chelicerates, excluding the sea spiders). The trunk ends in a four-segmented pygidium and bears eleven pairs of identical limbs, each of which is composed of three broad lamellate exopod flaps, and endopods are either reduced or absent. These overlapping exopod flaps resemble euchelicerate book gills, although they lack the diagnostic operculum9. In addition, the eyes of M. plenovenatrix were innervated by three optic neuropils, which strengthens the view that a complex malacostracan-like visual system10,11 might have been plesiomorphic for all crown euarthropods. These fossils thus show that chelicerates arose alongside mandibulates12 as benthic micropredators, at the heart of the Cambrian explosion.

@article{doi101038s4158601915254,
    author = "Aria, Cédric and Caron, Jean-Bernard",
    title = "A middle Cambrian arthropod with chelicerae and proto-book gills.",
    year = "2019",
    journal = "Nature",
    abstract = "The chelicerates are a ubiquitous and speciose group of animals that has a considerable ecological effect on modern terrestrial ecosystems-notably as predators of insects and also, for instance, as decomposers1. The fossil record shows that chelicerates diversified early in the marine ecosystems of the Palaeozoic era, by at least the Ordovician period2. However, the timing of chelicerate origins and the type of body plan that characterized the earliest members of this group have remained controversial. Although megacheirans3-5 have previously been interpreted as chelicerate-like, and habeliidans6 (including Sanctacaris7,8) have been suggested to belong to their immediate stem lineage, evidence for the specialized feeding appendages (chelicerae) that are diagnostic of the chelicerates has been lacking. Here we use exceptionally well-preserved and abundant fossil material from the middle Cambrian Burgess Shale (Marble Canyon, British Columbia, Canada) to show that Mollisonia plenovenatrix sp. nov. possessed robust but short chelicerae that were placed very anteriorly, between the eyes. This suggests that chelicerae evolved a specialized feeding function early on, possibly as a modification of short antennules. The head also encompasses a pair of large compound eyes, followed by three pairs of long, uniramous walking legs and three pairs of stout, gnathobasic masticatory appendages; this configuration links habeliidans with euchelicerates ('true' chelicerates, excluding the sea spiders). The trunk ends in a four-segmented pygidium and bears eleven pairs of identical limbs, each of which is composed of three broad lamellate exopod flaps, and endopods are either reduced or absent. These overlapping exopod flaps resemble euchelicerate book gills, although they lack the diagnostic operculum9. In addition, the eyes of M. plenovenatrix were innervated by three optic neuropils, which strengthens the view that a complex malacostracan-like visual system10,11 might have been plesiomorphic for all crown euarthropods. These fossils thus show that chelicerates arose alongside mandibulates12 as benthic micropredators, at the heart of the Cambrian explosion.",
    url = "https://pubmed.ncbi.nlm.nih.gov/31511691/",
    doi = "10.1038/s41586-019-1525-4",
    openalex = "W2972754927",
    pmid = "31511691",
    references = "doi101016jasd201507005, doi101038nature09038, doi101038nature11495, doi101038nature20804, doi101038ncomms4210, doi101073pnas1819366116, doi101080106351501753462876, doi101093sysbiosys029, doi101098rsos172206, doi101111j14754983201101124x, doi101130g24961a1, doi101186s1286201710887, openalexw645459046"
}

The trilobite Redlichia Cossmann, 1902 Cossmann, M. 1902. Rectification de la nomenclature. Revista Critica Paleozoologie, 16, 52. [Google Scholar] is an abundant element of the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte on Kangaroo Island, South Australia. Well-preserved, fully articulated specimens from this deposit are known to reach lengths of up to 25 cm, representing one of the largest known Cambrian trilobites. Until now, all Redlichia specimens from the EBS have been referred to Redlichia takooensis Lu, 1950 Lu, Y.-H. 1950. On the genus Redlichia with description of its new species. Geological Review, 15, 157–170. [In Chinese.] [Google Scholar], a species originally described from South China. Previous work recognized considerable differences in exoskeletal morphology among specimens of varying sizes, which was attributed to ontogeny. However, close examination of a large collection of recently acquired specimens shows that this variation actually represents two distinct morphs, interpreted here as separate species: R. takooensis, and a large, new species, Redlichia rex sp. nov. An analysis of morphological variation in holaspides (‘adults’) of the more common R. takooensis reveals considerable ontogenetic change occurred even during this later phase of growth. Some specimens of both Redlichia species from the EBS also exhibit exceptionally preserved soft-part anatomy, particularly the antennae and biramous appendages. Here, appendages (antenniform and biramous) and digestive structures are described, and biramous appendage reconstructions of R. rex sp. nov. are presented, which show a striking resemblance to some early Cambrian trilobites from South China. In particular, R. rex has a tripartite exopodite, as well as a dorsoventrally deep protopodite with gnathobasic spines used to shred or crush food items. Based on recent phylogenetic analyses, it is possible that an exopodite with tripartite subdivisions represents the plesiomorphic condition for Artiopoda (trilobites and kin). The digestive system of R. takooensis exhibits a series of paired digestive glands in the cephalon and anterior thorax, similar to those described for a number of other Cambrian and Ordovician trilobites.http://zoobank.org/urn:lsid:zoobank.org:pub:507BEAFC-4AFA-43F4-A5C4-49E4B58C658E

@article{doi1010801477201920191605411,
    author = "Holmes, James D. and Paterson, John R. and García‐Bellido, Diego C.",
    title = "The trilobite Redlichia from the lower Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia: systematics, ontogeny and soft-part anatomy",
    year = "2019",
    journal = "Journal of Systematic Palaeontology",
    abstract = "The trilobite Redlichia Cossmann, 1902 Cossmann, M. 1902. Rectification de la nomenclature. Revista Critica Paleozoologie, 16, 52. [Google Scholar] is an abundant element of the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte on Kangaroo Island, South Australia. Well-preserved, fully articulated specimens from this deposit are known to reach lengths of up to 25 cm, representing one of the largest known Cambrian trilobites. Until now, all Redlichia specimens from the EBS have been referred to Redlichia takooensis Lu, 1950 Lu, Y.-H. 1950. On the genus Redlichia with description of its new species. Geological Review, 15, 157–170. [In Chinese.] [Google Scholar], a species originally described from South China. Previous work recognized considerable differences in exoskeletal morphology among specimens of varying sizes, which was attributed to ontogeny. However, close examination of a large collection of recently acquired specimens shows that this variation actually represents two distinct morphs, interpreted here as separate species: R. takooensis, and a large, new species, Redlichia rex sp. nov. An analysis of morphological variation in holaspides (‘adults’) of the more common R. takooensis reveals considerable ontogenetic change occurred even during this later phase of growth. Some specimens of both Redlichia species from the EBS also exhibit exceptionally preserved soft-part anatomy, particularly the antennae and biramous appendages. Here, appendages (antenniform and biramous) and digestive structures are described, and biramous appendage reconstructions of R. rex sp. nov. are presented, which show a striking resemblance to some early Cambrian trilobites from South China. In particular, R. rex has a tripartite exopodite, as well as a dorsoventrally deep protopodite with gnathobasic spines used to shred or crush food items. Based on recent phylogenetic analyses, it is possible that an exopodite with tripartite subdivisions represents the plesiomorphic condition for Artiopoda (trilobites and kin). The digestive system of R. takooensis exhibits a series of paired digestive glands in the cephalon and anterior thorax, similar to those described for a number of other Cambrian and Ordovician trilobites.http://zoobank.org/urn:lsid:zoobank.org:pub:507BEAFC-4AFA-43F4-A5C4-49E4B58C658E",
    url = "https://doi.org/10.1080/14772019.2019.1605411",
    doi = "10.1080/14772019.2019.1605411",
    openalex = "W2951355339",
    references = "doi101016jasd201712001, doi10108003115510508619300, doi101080147720192013852903, doi101144jgs2015083, doi104202app20090024"
}

Burgess Shale-type fossil Lagerstätten provide the best evidence for deciphering the biotic patterns and magnitude of the Cambrian explosion. Here, we report a Lagerstätte from South China, the Qingjiang biota (~518 million years old), which is dominated by soft-bodied taxa from a distal shelf setting. The Qingjiang biota is distinguished by pristine carbonaceous preservation of labile organic features, a very high proportion of new taxa (~53%), and preliminary taxonomic diversity that suggests it could rival the Chengjiang and Burgess Shale biotas. Defining aspects of the Qingjiang biota include a high abundance of cnidarians, including both medusoid and polypoid forms; new taxa resembling extant kinorhynchs; and abundant larval or juvenile forms. This distinctive composition holds promise for providing insights into the evolution of Cambrian ecosystems across environmental gradients.

@article{doi101126scienceaau8800,
    author = "Fu, Dongjing and Tong, Guanghui and Dai, Tao and Liu, Wei and Yang, Yuning and Zhang, Yuan and Cui, Linhao and Li, Luoyang and Yun, Hao and Wu, Yu and Sun, Ao and Liu, Cong and Pei, Wenrui and Gaines, Robert R. and Zhang, Xingliang",
    title = "The Qingjiang biota—A Burgess Shale–type fossil Lagerstätte from the early Cambrian of South China",
    year = "2019",
    journal = "Science",
    abstract = "Burgess Shale-type fossil Lagerstätten provide the best evidence for deciphering the biotic patterns and magnitude of the Cambrian explosion. Here, we report a Lagerstätte from South China, the Qingjiang biota (\textasciitilde 518 million years old), which is dominated by soft-bodied taxa from a distal shelf setting. The Qingjiang biota is distinguished by pristine carbonaceous preservation of labile organic features, a very high proportion of new taxa (\textasciitilde 53\%), and preliminary taxonomic diversity that suggests it could rival the Chengjiang and Burgess Shale biotas. Defining aspects of the Qingjiang biota include a high abundance of cnidarians, including both medusoid and polypoid forms; new taxa resembling extant kinorhynchs; and abundant larval or juvenile forms. This distinctive composition holds promise for providing insights into the evolution of Cambrian ecosystems across environmental gradients.",
    url = "https://doi.org/10.1126/science.aau8800",
    doi = "10.1126/science.aau8800",
    openalex = "W2923733494",
    references = "doi1010029781118896372, doi101007s114340140419y, doi1010160016703795000382, doi101016b9780444594259000196, doi101016jearscirev201707017, doi101016jpalwor201510001, doi101017s108933260000276x, doi101038nature11874, doi101038ncomms4210, doi101073pnas1111784109, doi101073pnas1719962115, doi101111j14754983200700656x, doi101130g24961a1, doi101144jgs1582211, doi101144jgs2015083, doi10166612056, doi102110palo2009p09004r"
}

Parasite-host systems are pervasive in nature but are extremely difficult to convincingly identify in the fossil record. Here we report quantitative evidence of parasitism in the form of a unique, enduring life association between tube-dwelling organisms encrusted to densely clustered shells of a monospecific organophosphatic brachiopod assemblage from the lower Cambrian (Stage 4) of South China. Brachiopods with encrusting tubes have decreased biomass (indicating reduced fitness) compared to individuals without tubes. The encrusting tubes orient tightly in vectors matching the laminar feeding currents of the host, suggesting kleptoparasitism. With no convincing parasite-host interactions known from the Ediacaran, this widespread sessile association reveals intimate parasite-host animal systems arose in early Cambrian benthic communities and their emergence may have played a key role in driving the evolutionary and ecological innovations associated with the Cambrian radiation.

@article{doi101038s41467020163323,
    author = "Zhang, Zhifei and Strotz, Luke C. and Topper, Timothy P. and Chen, Feiyang and Chen, Yanlong and Liang, Yue and Zhang, Zhiliang and Skovsted, Christian B. and Brock, Glenn A.",
    title = "An encrusting kleptoparasite-host interaction from the early Cambrian",
    year = "2020",
    journal = "Nature Communications",
    abstract = "Parasite-host systems are pervasive in nature but are extremely difficult to convincingly identify in the fossil record. Here we report quantitative evidence of parasitism in the form of a unique, enduring life association between tube-dwelling organisms encrusted to densely clustered shells of a monospecific organophosphatic brachiopod assemblage from the lower Cambrian (Stage 4) of South China. Brachiopods with encrusting tubes have decreased biomass (indicating reduced fitness) compared to individuals without tubes. The encrusting tubes orient tightly in vectors matching the laminar feeding currents of the host, suggesting kleptoparasitism. With no convincing parasite-host interactions known from the Ediacaran, this widespread sessile association reveals intimate parasite-host animal systems arose in early Cambrian benthic communities and their emergence may have played a key role in driving the evolutionary and ecological innovations associated with the Cambrian radiation.",
    url = "https://doi.org/10.1038/s41467-020-16332-3",
    doi = "10.1038/s41467-020-16332-3",
    openalex = "W3030110323",
    references = "doi101016jearscirev201510015, doi101016jpalaeo200705023, doi101144jgs2015083, doi101144jgs2019043, doi105860choice416546"
}

, from the middle Cambrian Burgess Shale of Canada, also brooded young, but carried fewer (≤ 26 per clutch), larger (Ø, ~2.0 mm) eggs. The notable differences in clutch/egg sizes between these two species suggest an evolutionary trade-off between quantity and quality of offspring. The shift toward fewer, larger eggs might be an adaptive response to marine ecosystem changes through the early-middle Cambrian. We hypothesize that reproductive trade-offs might have facilitated the evolutionary success of early arthropods.

@article{doi101126sciadvaaz3376,
    author = "Ou, Qiang and Vannier, Jean and Yang, Xianfeng and Chen, Ailin and Mai, Huijuan and Shu, Degan and Han, Jian and Fu, Dongjing and Wang, Rong and Mayer, Georg",
    title = "Evolutionary trade-off in reproduction of Cambrian arthropods",
    year = "2020",
    journal = "Science Advances",
    abstract = ", from the middle Cambrian Burgess Shale of Canada, also brooded young, but carried fewer (≤ 26 per clutch), larger (Ø, \textasciitilde 2.0 mm) eggs. The notable differences in clutch/egg sizes between these two species suggest an evolutionary trade-off between quantity and quality of offspring. The shift toward fewer, larger eggs might be an adaptive response to marine ecosystem changes through the early-middle Cambrian. We hypothesize that reproductive trade-offs might have facilitated the evolutionary success of early arthropods.",
    url = "https://doi.org/10.1126/sciadv.aaz3376",
    doi = "10.1126/sciadv.aaz3376",
    openalex = "W3023357219",
    references = "doi101186s1286201812626"
}

BACKGROUND: The Chengjiang biota is one of the most species-rich Cambrian Konservat-Lagerstätten, and preserves a community dominated by non-biomineralized euarthropods. However, several Chengjiang euarthropods have an unfamiliar morphology, are extremely rare, or incompletely preserved. RESULTS: We employed micro-computed tomography to restudy the enigmatic euarthropod Jianshania furcatus. We reveal new morphological details, and demonstrate that the specimens assigned to this species represent two different taxa. The holotype of J. furcatus features a head shield with paired anterolateral notches, stalked lateral eyes, and an articulated tailspine with a bifurcate termination. The other specimen is formally redescribed as Xiaocaris luoi gen. et sp. nov., and is characterized by stalked eyes connected to an anterior sclerite, a subtrapezoidal head shield covering three small segments with reduced tergites, a trunk with 15 overlapping tergites with a well-developed dorsal keel, and paired tail flukes. CONCLUSIONS: The presence of antennae, biramous appendages with endopods composed of 15 articles, and multiple appendage pairs associated with the trunk tergites identify X. luoi nov. as a representative of Fuxianhuiida, an early branching group of stem-group euarthropods endemic to the early Cambrian of Southwest China. X. luoi nov. represents the fifth fuxianhuiid species described from the Chengjiang biota, and its functional morphology illuminates the ecological diversity of this important clade for understanding the early evolutionary history of euarthropods.

@article{doi101186s12862020016254,
    author = "Liu, Yu and Ortega‐Hernández, Javier and Chen, Hong and Mai, Huijuan and Zhai, Dayou and Hou, Xianguang",
    title = "Computed tomography sheds new light on the affinities of the enigmatic euarthropod Jianshania furcatus from the early Cambrian Chengjiang biota",
    year = "2020",
    journal = "BMC Evolutionary Biology",
    abstract = "BACKGROUND: The Chengjiang biota is one of the most species-rich Cambrian Konservat-Lagerstätten, and preserves a community dominated by non-biomineralized euarthropods. However, several Chengjiang euarthropods have an unfamiliar morphology, are extremely rare, or incompletely preserved. RESULTS: We employed micro-computed tomography to restudy the enigmatic euarthropod Jianshania furcatus. We reveal new morphological details, and demonstrate that the specimens assigned to this species represent two different taxa. The holotype of J. furcatus features a head shield with paired anterolateral notches, stalked lateral eyes, and an articulated tailspine with a bifurcate termination. The other specimen is formally redescribed as Xiaocaris luoi gen. et sp. nov., and is characterized by stalked eyes connected to an anterior sclerite, a subtrapezoidal head shield covering three small segments with reduced tergites, a trunk with 15 overlapping tergites with a well-developed dorsal keel, and paired tail flukes. CONCLUSIONS: The presence of antennae, biramous appendages with endopods composed of 15 articles, and multiple appendage pairs associated with the trunk tergites identify X. luoi nov. as a representative of Fuxianhuiida, an early branching group of stem-group euarthropods endemic to the early Cambrian of Southwest China. X. luoi nov. represents the fifth fuxianhuiid species described from the Chengjiang biota, and its functional morphology illuminates the ecological diversity of this important clade for understanding the early evolutionary history of euarthropods.",
    url = "https://doi.org/10.1186/s12862-020-01625-4",
    doi = "10.1186/s12862-020-01625-4",
    openalex = "W3032409411",
    references = "doi101007s114340140419y, doi101144jgs2019043, doi101186s1286201812626"
}

Understanding the functional morphology and mobility of appendages of fossil animals is important for exploring ecological traits such as feeding and locomotion. Previous work on fossils from the 518 million-year-old Chengjiang biota of China was based mainly on two-dimensional information captured from the surface of the specimens. Only recently, μCT techniques started to reveal almost the entire, though flattened and compressed, three-dimensionally preserved morphologies of the arthropods from Chengjiang. This allows more accurate work on reconstructing the possible movement of certain structures such as the appendages. Here, we present a workflow on how to reconstruct the mobility of a limb of the early Chengjiang arthropod Ercaicunia multinodosa from the famous Chinese fossil site. Based on μCT scans of the fossil, we rendered surface models of the 13th-15th right endopods using the 3D visualization and 3D-rendering software Amira. The 3D objects then were postprocessed (Collapse Hierarchy, Unify Normals) in SAP 3D Visual Enterprise Author before being imported into the 3D animation program Autodesk Maya 2020. Using the add-on tool X_ROMM in Maya, we illustrate step-by-step on how to make the articles of the limbs swing-in toward each other. Eventually, we propose several possible limb movements of E. multinodosa, which helps to understand how this early arthropod could have moved its endopods.

@article{doi101002jemt23628,
    author = "Schmidt, Michel and Liu, Yu and Zhai, Dayou and Hou, Xianguang and Melzer, Roland R",
    title = "Moving legs: A workflow on how to generate a flexible endopod of the 518 million-year-old Chengjiang arthropod Ercaicunia multinodosa using 3D-kinematics (Cambrian, China).",
    year = "2021",
    journal = "Microscopy research and technique",
    abstract = "Understanding the functional morphology and mobility of appendages of fossil animals is important for exploring ecological traits such as feeding and locomotion. Previous work on fossils from the 518 million-year-old Chengjiang biota of China was based mainly on two-dimensional information captured from the surface of the specimens. Only recently, μCT techniques started to reveal almost the entire, though flattened and compressed, three-dimensionally preserved morphologies of the arthropods from Chengjiang. This allows more accurate work on reconstructing the possible movement of certain structures such as the appendages. Here, we present a workflow on how to reconstruct the mobility of a limb of the early Chengjiang arthropod Ercaicunia multinodosa from the famous Chinese fossil site. Based on μCT scans of the fossil, we rendered surface models of the 13th-15th right endopods using the 3D visualization and 3D-rendering software Amira. The 3D objects then were postprocessed (Collapse Hierarchy, Unify Normals) in SAP 3D Visual Enterprise Author before being imported into the 3D animation program Autodesk Maya 2020. Using the add-on tool X\_ROMM in Maya, we illustrate step-by-step on how to make the articles of the limbs swing-in toward each other. Eventually, we propose several possible limb movements of E. multinodosa, which helps to understand how this early arthropod could have moved its endopods.",
    url = "https://pubmed.ncbi.nlm.nih.gov/33155750/",
    doi = "10.1002/jemt.23628",
    openalex = "W3094896445",
    pmid = "33155750",
    references = "doi101002jez589, doi101016b978012387582250040x, doi101017s1464793103006274, doi101038s4158601808512, doi101111j155856461965tb01720x, doi10111712935640, doi101130g206401, doi1023072406439, doi105860choice416546, openalexw1573076930"
}

BACKGROUND: The Chengjiang biota from southwest China (518-million-years old, early Cambrian) has yielded nearly 300 species, of which more than 80 species represent early chelicerates, crustaceans and relatives. The application of µCT-techniques combined with 3D software (e.g., Drishti), has been shown to be a powerful tool in revealing and analyzing 3D features of the Chengjiang euarthropods. In order to address several open questions that remained from previous studies on the morphology of the xandarellid euarthropod Sinoburius lunaris, we reinvestigated the µCT data with Amira to obtain a different approach of visualization and to generate new volume-rendered models. Furthermore, we used Blender to design 3D models showing aspects of intraspecific variation. RESULTS: New findings are: (1) antennulae consist of additional proximal articles that have not been detected before; (2) compared to other appendages, the second post-antennular appendage has a unique shape, and its endopod is comprised of only five articles (instead of seven); (3) the pygidium bears four pairs of appendages which are observed in all specimens. On the other hand, differences between specimens also have been detected. These include the presence/absence of diplotergites resulting in different numbers of post-antennular appendages and tergites and different distances between the tip of the hypostome and the anterior margin of the head shield. CONCLUSIONS: Those new observations reveal intraspecific variation among Chengjiang euarthropods not observed before and encourage considerations about possible sexual dimorphic pairs or ontogenetic stages. Sinoburius lunaris is a variable species with respect to its morphological characters, cautioning that taxon-specific variabilities need to be considered when exploring new species.

@article{doi101186s12862021018541,
    author = "Schmidt, Michel and Liu, Yu and Hou, Xianguang and Haug, Joachim T. and Haug, Carolin and Mai, Huijan and Melzer, Roland R.",
    title = "Intraspecific variation in the Cambrian: new observations on the morphology of the Chengjiang euarthropod Sinoburius lunaris",
    year = "2021",
    journal = "BMC Ecology and Evolution",
    abstract = "BACKGROUND: The Chengjiang biota from southwest China (518-million-years old, early Cambrian) has yielded nearly 300 species, of which more than 80 species represent early chelicerates, crustaceans and relatives. The application of µCT-techniques combined with 3D software (e.g., Drishti), has been shown to be a powerful tool in revealing and analyzing 3D features of the Chengjiang euarthropods. In order to address several open questions that remained from previous studies on the morphology of the xandarellid euarthropod Sinoburius lunaris, we reinvestigated the µCT data with Amira to obtain a different approach of visualization and to generate new volume-rendered models. Furthermore, we used Blender to design 3D models showing aspects of intraspecific variation. RESULTS: New findings are: (1) antennulae consist of additional proximal articles that have not been detected before; (2) compared to other appendages, the second post-antennular appendage has a unique shape, and its endopod is comprised of only five articles (instead of seven); (3) the pygidium bears four pairs of appendages which are observed in all specimens. On the other hand, differences between specimens also have been detected. These include the presence/absence of diplotergites resulting in different numbers of post-antennular appendages and tergites and different distances between the tip of the hypostome and the anterior margin of the head shield. CONCLUSIONS: Those new observations reveal intraspecific variation among Chengjiang euarthropods not observed before and encourage considerations about possible sexual dimorphic pairs or ontogenetic stages. Sinoburius lunaris is a variable species with respect to its morphological characters, cautioning that taxon-specific variabilities need to be considered when exploring new species.",
    url = "https://doi.org/10.1186/s12862-021-01854-1",
    doi = "10.1186/s12862-021-01854-1",
    openalex = "W3176179897",
    references = "doi101002jemt23628, doi10100797814757908323, doi101016b978012387582250040x, doi101017s1464793103006274, doi1010371082989x4184, doi10111712935640, doi1023072412740, doi1023072528217, doi105860choice273873, doi105860choice416546, openalexw2134978213"
}

The origin of mandibulates, the hyperdiverse arthropod group that includes pancrustaceans and myriapods, dates back to the Cambrian. Bivalved arthropod groups such as hymenocarines have been argued to be early mandibulates, but many species are still poorly known, and their affinities remain uncertain. One of the most common and globally distributed Cambrian bivalved arthropods is Tuzoia. Originally described in 1912 from the Burgess Shale based on isolated carapaces, its full anatomy has remained largely unknown. Here, we describe new specimens of Tuzoia from the Canadian Burgess Shale (Wuliuan, Cambrian) showcasing exceptionally preserved soft tissues, allowing for the first comprehensive reconstruction of its anatomy, ecology and evolutionary affinities. The head bears antennae and differentiated cephalic appendages. The body is divided into a cephalothorax, a homonomous trunk bearing ca 10 pairs of legs with heptopodomerous endopods and enlarged basipods, and a tail fan with two pairs of caudal rami. These traits suggest that Tuzoia swam along the seafloor and used its spinose legs for predation or scavenging. Tuzoia is retrieved by a Bayesian phylogenetic analysis as an early mandibulate hymenocarine lineage, exemplifying the rapid diversification of this group in open marine environments during the Cambrian Explosion.

@article{doi101098rsos220933,
    author = "Izquierdo‐López, Alejandro and Caron, Jean‐Bernard",
    title = "The problematic Cambrian arthropod Tuzoia and the origin of mandibulates revisited",
    year = "2022",
    journal = "Royal Society Open Science",
    abstract = "The origin of mandibulates, the hyperdiverse arthropod group that includes pancrustaceans and myriapods, dates back to the Cambrian. Bivalved arthropod groups such as hymenocarines have been argued to be early mandibulates, but many species are still poorly known, and their affinities remain uncertain. One of the most common and globally distributed Cambrian bivalved arthropods is Tuzoia. Originally described in 1912 from the Burgess Shale based on isolated carapaces, its full anatomy has remained largely unknown. Here, we describe new specimens of Tuzoia from the Canadian Burgess Shale (Wuliuan, Cambrian) showcasing exceptionally preserved soft tissues, allowing for the first comprehensive reconstruction of its anatomy, ecology and evolutionary affinities. The head bears antennae and differentiated cephalic appendages. The body is divided into a cephalothorax, a homonomous trunk bearing ca 10 pairs of legs with heptopodomerous endopods and enlarged basipods, and a tail fan with two pairs of caudal rami. These traits suggest that Tuzoia swam along the seafloor and used its spinose legs for predation or scavenging. Tuzoia is retrieved by a Bayesian phylogenetic analysis as an early mandibulate hymenocarine lineage, exemplifying the rapid diversification of this group in open marine environments during the Cambrian Explosion.",
    url = "https://doi.org/10.1098/rsos.220933",
    doi = "10.1098/rsos.220933",
    openalex = "W4310803405",
    references = "doi101016jcub201904057, doi101017s1464793103006274, doi101038ncomms3485, doi101093bioinformaticsbtq706, doi101093bioinformaticsbty633, doi101093sysbiosys029, doi101093sysbiosyy032, doi101098rsos191350, doi101098rsos220933, doi101098rspb20100590, doi101098rstb20210034, doi1011112041210x12035, doi101111brv12864, doi1018637jssv056i13"
}

The Cambrian Stage 3 Chengjiang biota in South China is one of the most influential Konservat-Lagerstätten worldwide thanks to the fossilization of diverse non-biomineralizing organisms through pyritization. Despite their contributions to understanding the evolution of early animals, several Chengjiang species remain poorly known owing to their scarcity and/or incomplete preservation. Here, we use micro-computed tomography to reveal in detail the ventral appendage organization of the enigmatic non-trilobite artiopod Pygmaclypeatus daziensis-one of the rarest euarthropods in Chengjiang-and explore its functional ecology and broader evolutionary significance. Pygmaclypeatus daziensis possesses a set of uniramous antennae and 14 pairs of post-antennal biramous appendages, the latter of which show an unexpectedly high degree of heteronomy based on the localized differentiation of the protopodite, endopodite and exopodite along with the antero-posterior body axis. The small body size (less than 2 cm), the presence of delicate spinose endites and well-developed exopodites with multiple paddle-shaped lamellae on the appendages of P. daziensis indicate a nekto-benthic mode of life and a scavenging/detritus feeding strategy. Pygmaclypeatus daziensis shows that appendage heteronomy is phylogenetically widespread within Artiopoda-the megadiverse clade that includes trilobites and their relatives with non-biomineralizing exoskeletons-and suggests that a single exopodite lobe with paddle-like lamellae is ancestral for this clade. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.

@article{doi101098rstb20210030,
    author = "Schmidt, Michel and Hou, Xianguang and Zhai, Dayou and Mai, Huijuan and Belojević, Jelena and Chen, Xiaohan and Melzer, Roland R and Ortega-Hernández, Javier and Liu, Yu",
    title = "Before trilobite legs: Pygmaclypeatus daziensis reconsidered and the ancestral appendicular organization of Cambrian artiopods.",
    year = "2022",
    journal = "Philosophical transactions of the Royal Society of London. Series B, Biological sciences",
    abstract = "The Cambrian Stage 3 Chengjiang biota in South China is one of the most influential Konservat-Lagerstätten worldwide thanks to the fossilization of diverse non-biomineralizing organisms through pyritization. Despite their contributions to understanding the evolution of early animals, several Chengjiang species remain poorly known owing to their scarcity and/or incomplete preservation. Here, we use micro-computed tomography to reveal in detail the ventral appendage organization of the enigmatic non-trilobite artiopod Pygmaclypeatus daziensis-one of the rarest euarthropods in Chengjiang-and explore its functional ecology and broader evolutionary significance. Pygmaclypeatus daziensis possesses a set of uniramous antennae and 14 pairs of post-antennal biramous appendages, the latter of which show an unexpectedly high degree of heteronomy based on the localized differentiation of the protopodite, endopodite and exopodite along with the antero-posterior body axis. The small body size (less than 2 cm), the presence of delicate spinose endites and well-developed exopodites with multiple paddle-shaped lamellae on the appendages of P. daziensis indicate a nekto-benthic mode of life and a scavenging/detritus feeding strategy. Pygmaclypeatus daziensis shows that appendage heteronomy is phylogenetically widespread within Artiopoda-the megadiverse clade that includes trilobites and their relatives with non-biomineralizing exoskeletons-and suggests that a single exopodite lobe with paddle-like lamellae is ancestral for this clade. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC8819370/",
    doi = "10.1098/rstb.2021.0030",
    openalex = "W4220880714",
    pmcid = "PMC8819370",
    pmid = "35125003",
    references = "doi1010029781118896372, doi101016jpalaeo200303001, doi101017s1464793103006274, doi101038ncomms3485, doi101038s4158602028837, doi101098rstb19810164, doi101111cla12160, doi101111j10960031200800217x, doi10111712935640, doi101130g206401, doi101146annurevearth35031306140258"
}

Biramous appendages are a common feature among modern marine arthropods that evolved deep in arthropod phylogeny. The branched appendage of Cambrian arthropods has long been considered as the ancient biramous limb, sparking numerous investigations on its origin and evolution. Here, we report a new arthropod, Erratus sperare gen. et sp. nov., from the Lower Cambrian (Stage 3, 520 Ma) Chengjiang biota of Yunnan, China, with unique trunk appendages formed of lateral anomalocaridid-type flaps and ventral subconical endopods. These appendages represent an intermediate stage of biramous limb evolution, i.e. from 'two pairs of flap appendages' in radiodonts to 'flap + endopod' in Erratus, to 'exopod + endopod' in the rest of carapace-bearing arthropods that populate the basal region of the upper-stem lineage arthropods (deuteropods). The new species occupies a phylogenetic position at the first node closer to deuteropods than to radiodonts, and therefore pinpoints the earliest occurrence of the endopod within Deuteropoda. The primitive endopod is weakly sclerotized, and has unspecialized segments without endites or claw. The findings might support previous claims that the outer branch of the biramous limb of fossil marine arthropods, such as trilobites, is not a true exopod, but is instead a modified exite. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.

@article{doi101098rstb20210034,
    author = "Fu, Dongjing and Legg, David A and Daley, Allison C and Budd, Graham E and Wu, Yu and Zhang, Xingliang",
    title = "The evolution of biramous appendages revealed by a carapace-bearing Cambrian arthropod.",
    year = "2022",
    journal = "Philosophical transactions of the Royal Society of London. Series B, Biological sciences",
    abstract = "Biramous appendages are a common feature among modern marine arthropods that evolved deep in arthropod phylogeny. The branched appendage of Cambrian arthropods has long been considered as the ancient biramous limb, sparking numerous investigations on its origin and evolution. Here, we report a new arthropod, Erratus sperare gen. et sp. nov., from the Lower Cambrian (Stage 3, 520 Ma) Chengjiang biota of Yunnan, China, with unique trunk appendages formed of lateral anomalocaridid-type flaps and ventral subconical endopods. These appendages represent an intermediate stage of biramous limb evolution, i.e. from 'two pairs of flap appendages' in radiodonts to 'flap + endopod' in Erratus, to 'exopod + endopod' in the rest of carapace-bearing arthropods that populate the basal region of the upper-stem lineage arthropods (deuteropods). The new species occupies a phylogenetic position at the first node closer to deuteropods than to radiodonts, and therefore pinpoints the earliest occurrence of the endopod within Deuteropoda. The primitive endopod is weakly sclerotized, and has unspecialized segments without endites or claw. The findings might support previous claims that the outer branch of the biramous limb of fossil marine arthropods, such as trilobites, is not a true exopod, but is instead a modified exite. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC8819368/",
    doi = "10.1098/rstb.2021.0034",
    openalex = "W4210932836",
    pmcid = "PMC8819368",
    pmid = "35125000",
    references = "doi101017s1464793103006274, doi101038nature07890, doi101038nature11874, doi101038nature14256, doi101038ncomms3485, doi101098rspb20121958, doi101098rstb20210034, doi101111brv12168, doi101111j10960031200800209x, doi101126science1169514, doi105860choice416546"
}

The rise of arthropods is a decisive event in the history of life. Likely the first animals to have established themselves on land and in the air, arthropods have pervaded nearly all ecosystems and have become pillars of the planet's ecological networks. Forerunners of this saga, exceptionally well-preserved Palaeozoic fossils recently discovered or re-discovered using new approaches and techniques have elucidated the precocious appearance of extant lineages at the onset of the Cambrian explosion, and pointed to the critical role of the plankton and hard integuments in early arthropod diversification. The notion put forward at the beginning of the century that the acquisition of extant arthropod characters was stepwise and represented by the majority of Cambrian fossil taxa is being rewritten. Although some key traits leading to Euarthropoda are indeed well documented along a diversified phylogenetic stem, this stem led to several speciose and ecologically diverse radiations leaving descendants late into the Palaeozoic, and a large part, if not all of the Cambrian euarthropods can now be placed on either of the two extant lineages: Mandibulata and Chelicerata. These new observations and discoveries have altered our view on the nature and timing of the Cambrian explosion and clarified diagnostic characters at the origin of extant arthropods, but also raised new questions, especially with respect to cephalic plasticity. There is now strong evidence that early arthropods shared a homologous frontalmost appendage, coined here the cheira, which likely evolved into antennules and chelicerae, but other aspects, such as brain and labrum evolution, are still subject to active debate. The early evolution of panarthropods was generally driven by increased mastication and predation efficiency and sophistication, but a wealth of recent studies have also highlighted the prevalent role of suspension-feeding, for which early panarthropods developed their own adaptive feedback through both specialized appendages and the diversification of small, morphologically differentiated larvae. In a context of general integumental differentiation and hardening across Cambrian metazoans, arthrodization of body and limbs notably prompted two diverging strategies of basipod differentiation, which arguably became founding criteria in the divergence of total-groups Mandibulata and Chelicerata. The kinship of trilobites and their relatives remains a source of disagreement, but a recent topological solution, termed the 'deep split', could embed Artiopoda as sister taxa to chelicerates and constitute definitive support for Arachnomorpha. Although Cambrian fossils have been critical to all these findings, data of exceptional quality have also been accumulating from other Palaeozoic Konservat-Lagerstätten, and a better integration of this information promises a much more complete and elaborate picture of early arthropod evolution in the near future. From the broader perspective of a total-evidence approach to the understanding of life's history, and despite persisting systematic debates and new interpretative challenges, various advances based on palaeontological evidence open the prospect of finally using the full potential of the most diverse animal phylum to investigate macroevolutionary patterns and processes.

@article{doi101111brv12864,
    author = "Aria, Cédric",
    title = "The origin and early evolution of arthropods",
    year = "2022",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "The rise of arthropods is a decisive event in the history of life. Likely the first animals to have established themselves on land and in the air, arthropods have pervaded nearly all ecosystems and have become pillars of the planet's ecological networks. Forerunners of this saga, exceptionally well-preserved Palaeozoic fossils recently discovered or re-discovered using new approaches and techniques have elucidated the precocious appearance of extant lineages at the onset of the Cambrian explosion, and pointed to the critical role of the plankton and hard integuments in early arthropod diversification. The notion put forward at the beginning of the century that the acquisition of extant arthropod characters was stepwise and represented by the majority of Cambrian fossil taxa is being rewritten. Although some key traits leading to Euarthropoda are indeed well documented along a diversified phylogenetic stem, this stem led to several speciose and ecologically diverse radiations leaving descendants late into the Palaeozoic, and a large part, if not all of the Cambrian euarthropods can now be placed on either of the two extant lineages: Mandibulata and Chelicerata. These new observations and discoveries have altered our view on the nature and timing of the Cambrian explosion and clarified diagnostic characters at the origin of extant arthropods, but also raised new questions, especially with respect to cephalic plasticity. There is now strong evidence that early arthropods shared a homologous frontalmost appendage, coined here the cheira, which likely evolved into antennules and chelicerae, but other aspects, such as brain and labrum evolution, are still subject to active debate. The early evolution of panarthropods was generally driven by increased mastication and predation efficiency and sophistication, but a wealth of recent studies have also highlighted the prevalent role of suspension-feeding, for which early panarthropods developed their own adaptive feedback through both specialized appendages and the diversification of small, morphologically differentiated larvae. In a context of general integumental differentiation and hardening across Cambrian metazoans, arthrodization of body and limbs notably prompted two diverging strategies of basipod differentiation, which arguably became founding criteria in the divergence of total-groups Mandibulata and Chelicerata. The kinship of trilobites and their relatives remains a source of disagreement, but a recent topological solution, termed the 'deep split', could embed Artiopoda as sister taxa to chelicerates and constitute definitive support for Arachnomorpha. Although Cambrian fossils have been critical to all these findings, data of exceptional quality have also been accumulating from other Palaeozoic Konservat-Lagerstätten, and a better integration of this information promises a much more complete and elaborate picture of early arthropod evolution in the near future. From the broader perspective of a total-evidence approach to the understanding of life's history, and despite persisting systematic debates and new interpretative challenges, various advances based on palaeontological evidence open the prospect of finally using the full potential of the most diverse animal phylum to investigate macroevolutionary patterns and processes.",
    url = "https://doi.org/10.1111/brv.12864",
    doi = "10.1111/brv.12864",
    openalex = "W4224942167",
    references = "doi1010079789401149044, doi101016jasd201507005, doi101016jasd201509003, doi101016jasd201610011, doi101016jasd2021101048, doi101016jbiocon201901020, doi101016jcub202005085, doi101016jpalaeo200703046, doi101017s009483730001263x, doi101038nature08742, doi101038ncomms4560, doi101038s4158601915254, doi101038s4158602028837, doi101080147720192012732723, doi101093molbevmsu235, doi101098rsos172206, doi101098rsos191350, doi101098rspb20191079, doi101098rspb20192370, doi101098rstb20140313, doi101098rstb20210034, doi101111pala12236, doi101126science11536548, doi101126science1251817, doi101126scienceaaf2201, doi101146annurevecolsys011720124437, doi101186s1286201710887, doi101186s1286201812626, doi101186s1286201915607, doi101186s1291501602714, doi101371journalpone0124979, doi101666090751, doi105860choice273873, openalexw2185676932"
}

, also known from Chengjiang, and strengthens the close relationship of these taxa that have been suggested by previous studies as early-branching representatives of Trilobitomorpha. Cephalic appendages suggest this animal might be a scavenger, possibly feeding on soft-bodied organisms. Different pairs of pygidial appendages suggest an anamorphic post-embryonic ontogeny, which adds to the understanding of the developmental mode of Cambrian artiopods, and further supports the statement that post-hatching segment addition occurred in the ancestor of Euarthropoda.

@article{doi103390biology11081235,
    author = "Zhang, Maoyin and Liu, Yu and Hou, Xianguang and Ortega‐Hernández, Javier and Mai, Huijuan and Schmidt, Michel and Melzer, Roland R. and Guo, Jin",
    title = "Ventral Morphology of the Non-Trilobite Artiopod Retifacies abnormalis Hou, Chen \& Lu, 1989, from the Early Cambrian Chengjiang Biota, China",
    year = "2022",
    journal = "Biology",
    abstract = ", also known from Chengjiang, and strengthens the close relationship of these taxa that have been suggested by previous studies as early-branching representatives of Trilobitomorpha. Cephalic appendages suggest this animal might be a scavenger, possibly feeding on soft-bodied organisms. Different pairs of pygidial appendages suggest an anamorphic post-embryonic ontogeny, which adds to the understanding of the developmental mode of Cambrian artiopods, and further supports the statement that post-hatching segment addition occurred in the ancestor of Euarthropoda.",
    url = "https://doi.org/10.3390/biology11081235",
    doi = "10.3390/biology11081235",
    openalex = "W4292547135",
    references = "doi101098rstb20210030, doi101186s1286201812626"
}

Abstract Artiopoda was a diverse group of Palaeozoic euarthropods that proliferated in the early Palaeozoic, epitomized by the ubiquitous trilobites. Their possible phylogenetic position outside mandibulates and chelicerates offers the potential for understanding the evolution of euarthropods in more detail. However, this opportunity remains unexploited given that identification of deep‐splitting artiopodans remains to be fully explored. Here, we describe a new non‐trilobite artiopodan from the lower Cambrian Sirius Passet Lagerstätte, North Greenland. Thulaspis tholops gen. et sp. nov. is a large species with a broad, domed head shield, followed by a trunk consisting of 15 thoracic tergites and a small pygidium, giving the body an ovoid appearance when viewed dorsally. Thulaspis is distinctive with its rounded genae and anterior thoracic pleural tips, as well as short pleural spines posteriorly. A heart‐shaped hypostome with an anterior lobe is present. Appendages, partly obscured by the tergal skeleton, have many moderate length gnathobasic spines, and large flap‐like exopods with a fringe of small setae. Cladistic analyses recover Thulaspis as the sister taxon to Squamacula, a genus found in the Chengjiang and Emu Bay Shale biotas, in either a polytomy with a number of artiopodan taxa or as a sister group to all other artiopodans, indicating an important role in understanding the roots of artiopodan anatomy and evolution.

@article{doi101002spp21495,
    author = "Berks, Harry O. and Nielsen, Morten Lunde and Flannery‐Sutherland, Joseph T. and Nielsen, Arne Thorshøj and Park, Tae‐Yoon S. and Vinther, Jakob",
    title = "A possibly deep branching artiopodan arthropod from the lower Cambrian Sirius Passet Lagerstätte (North Greenland)",
    year = "2023",
    journal = "Papers in Palaeontology",
    abstract = "Abstract Artiopoda was a diverse group of Palaeozoic euarthropods that proliferated in the early Palaeozoic, epitomized by the ubiquitous trilobites. Their possible phylogenetic position outside mandibulates and chelicerates offers the potential for understanding the evolution of euarthropods in more detail. However, this opportunity remains unexploited given that identification of deep‐splitting artiopodans remains to be fully explored. Here, we describe a new non‐trilobite artiopodan from the lower Cambrian Sirius Passet Lagerstätte, North Greenland. Thulaspis tholops gen. et sp. nov. is a large species with a broad, domed head shield, followed by a trunk consisting of 15 thoracic tergites and a small pygidium, giving the body an ovoid appearance when viewed dorsally. Thulaspis is distinctive with its rounded genae and anterior thoracic pleural tips, as well as short pleural spines posteriorly. A heart‐shaped hypostome with an anterior lobe is present. Appendages, partly obscured by the tergal skeleton, have many moderate length gnathobasic spines, and large flap‐like exopods with a fringe of small setae. Cladistic analyses recover Thulaspis as the sister taxon to Squamacula, a genus found in the Chengjiang and Emu Bay Shale biotas, in either a polytomy with a number of artiopodan taxa or as a sister group to all other artiopodans, indicating an important role in understanding the roots of artiopodan anatomy and evolution.",
    url = "https://doi.org/10.1002/spp2.1495",
    doi = "10.1002/spp2.1495",
    openalex = "W4380990140",
    references = "doi101002spp21495, doi101016jcub201904057, doi101038326181a0, doi101038nature13010, doi101038ncomms3485, doi10108000241160410004764, doi101098rstb20210030, doi1011111475498300080, doi101111brv12864, doi101111j109583122000tb01279x, doi101111j109600311999tb00277x, doi101111j109600311999tb00278x, doi101111j10960031200800217x, doi103140bullgeosci1158"
}

@article{doi101016jcub202308022,
    author = "O’Flynn, Robert J. and Liu, Yu and Hou, Xianguang and Mai, Huijuan and Yu, Mengxiao and Zhuang, Songling and Williams, Mark and Guo, Jin and Edgecombe, Gregory D.",
    title = "The early Cambrian Kylinxia zhangi and evolution of the arthropod head",
    year = "2023",
    journal = "Current Biology",
    url = "https://doi.org/10.1016/j.cub.2023.08.022",
    doi = "10.1016/j.cub.2023.08.022",
    openalex = "W4386226585",
    references = "doi101016jasd2021101048, doi101098rstb20210030, doi101111brv12864"
}

was not arthrodized. The results of our phylogenetic analyses recover isoxyids as some of the earliest branching sclerotized euarthropods, and strengthens the hypothesis that arthropodized biramous appendages evolved before full body arthrodization.

@article{doi101098rspb20230335,
    author = "Zhang, Caixia and Liu, Yu and Ortega‐Hernández, Javier and Wolfe, Joanna M. and Jin, Changfei and Mai, Huijuan and Hou, Xianguang and Guo, Jin and Zhai, Dayou",
    title = "Three-dimensional morphology of the biramous appendages in Isoxys from the early Cambrian of South China, and its implications for early euarthropod evolution",
    year = "2023",
    journal = "Proceedings of the Royal Society B Biological Sciences",
    abstract = "was not arthrodized. The results of our phylogenetic analyses recover isoxyids as some of the earliest branching sclerotized euarthropods, and strengthens the hypothesis that arthropodized biramous appendages evolved before full body arthrodization.",
    url = "https://doi.org/10.1098/rspb.2023.0335",
    doi = "10.1098/rspb.2023.0335",
    openalex = "W4366247954",
    references = "doi101098rstb20210030, doi101098rstb20210034"
}

Abstract The Cambrian (Series 2, Stage 3) Qingjiang Lagerstätte of South China is one of the most diverse Burgess Shale‐type deposits around the world, yielding abundant non‐biomineralized fossils. Radiodonta, a taxonomically and ecologically diverse stem‐euarthropod group, has been generally thought to represent the largest consumers in early Palaeozoic marine ecosystems. Here we describe several new radiodont specimens from the Qingjiang Lagerstätte assigned to various groups, including Stanleycaris qingjiangensis sp. nov., a new type of hurdiid head carapace, one possible Hurdia carapace, and two partial appendages with uncertain affinities. These specimens not only extend the geographic and stratigraphic range of these taxa, they also illuminate the diversity of radiodonts (in particular hurdiids) in their early evolutionary history. Radiodont palaeobiogeographic patterns are visualized using network analysis. Laurentia and South China share many members at the genus level, Anomalocaris is the most cosmopolitan taxon, but most genera are endemic. Radiodonts show a high initial diversity that declines through the early Palaeozoic, enabling three diversification phases of radiodonts to be recognized: the thriving phase (Cambrian Series 2), declining phase (Cambrian Miaolingian) and terminal phase (Cambrian Furongian to Ordovician Floian).

@article{doi101002spp21583,
    author = "Wu, Yu and Pates, Stephen and Zhang, Mingjing and Lin, Weiliang and Ma, Jiaxin and Liu, Cong and Wu, Yuheng and Zhang, Xingliang and Fu, Dongjing",
    title = "Exceptionally preserved radiodont arthropods from the lower Cambrian (Stage 3) Qingjiang Lagerstätte of Hubei, South China and the biogeographic and diversification patterns of radiodonts",
    year = "2024",
    journal = "Papers in Palaeontology",
    abstract = "Abstract The Cambrian (Series 2, Stage 3) Qingjiang Lagerstätte of South China is one of the most diverse Burgess Shale‐type deposits around the world, yielding abundant non‐biomineralized fossils. Radiodonta, a taxonomically and ecologically diverse stem‐euarthropod group, has been generally thought to represent the largest consumers in early Palaeozoic marine ecosystems. Here we describe several new radiodont specimens from the Qingjiang Lagerstätte assigned to various groups, including Stanleycaris qingjiangensis sp. nov., a new type of hurdiid head carapace, one possible Hurdia carapace, and two partial appendages with uncertain affinities. These specimens not only extend the geographic and stratigraphic range of these taxa, they also illuminate the diversity of radiodonts (in particular hurdiids) in their early evolutionary history. Radiodont palaeobiogeographic patterns are visualized using network analysis. Laurentia and South China share many members at the genus level, Anomalocaris is the most cosmopolitan taxon, but most genera are endemic. Radiodonts show a high initial diversity that declines through the early Palaeozoic, enabling three diversification phases of radiodonts to be recognized: the thriving phase (Cambrian Series 2), declining phase (Cambrian Miaolingian) and terminal phase (Cambrian Furongian to Ordovician Floian).",
    url = "https://doi.org/10.1002/spp2.1583",
    doi = "10.1002/spp2.1583",
    openalex = "W4401789453",
    references = "doi101016jjseaes201702043, doi101098rsos191350, doi101098rsos220933, doi101098rspb20230638, doi103389feart20231160285"
}

Abstract Phylogenetic analysis demonstrates that Kuamaia lata, a helmetiid euarthropod from the lower Cambrian (Series 2, Stage 3) Chengjiang Konservat-Lagerstätte, nests robustly within Artiopoda, the euarthropod clade including trilobitomorphs. Microtomography of new specimens of K. lata reveals details of morphology, notably a six-segmented head and raptorial frontal appendages, the latter contrasting with filiform antennae considered to be a diagnostic character of Artiopoda. Phylogenetic analyses demonstrate that a raptorial frontal appendage is a symplesiomorphy for upper stem-group euarthropods, retained across a swathe of tree space, but evolved secondarily in K. lata from an antenna within Artiopoda. The phylogenetic position of K. lata adds support to a six-segmented head being an ancestral state for upper stem- and crown-group euarthropods.

@article{doi101017jpa202433,
    author = "O’Flynn, Robert J. and Williams, Mark and Liu, Yu and Hou, Xian-guang and Guo, Jin and Edgecombe, Gregory D.",
    title = "The early Cambrian Kuamaia lata, an artiopodan euarthropod with a raptorial frontal appendage",
    year = "2024",
    journal = "Journal of Paleontology",
    abstract = "Abstract Phylogenetic analysis demonstrates that Kuamaia lata, a helmetiid euarthropod from the lower Cambrian (Series 2, Stage 3) Chengjiang Konservat-Lagerstätte, nests robustly within Artiopoda, the euarthropod clade including trilobitomorphs. Microtomography of new specimens of K. lata reveals details of morphology, notably a six-segmented head and raptorial frontal appendages, the latter contrasting with filiform antennae considered to be a diagnostic character of Artiopoda. Phylogenetic analyses demonstrate that a raptorial frontal appendage is a symplesiomorphy for upper stem-group euarthropods, retained across a swathe of tree space, but evolved secondarily in K. lata from an antenna within Artiopoda. The phylogenetic position of K. lata adds support to a six-segmented head being an ancestral state for upper stem- and crown-group euarthropods.",
    url = "https://doi.org/10.1017/jpa.2024.33",
    doi = "10.1017/jpa.2024.33",
    openalex = "W4407421618",
    references = "doi101098rstb20210030"
}

Radiodonts, a diverse clade of early Palaeozoic stem-group euarthropods, have provided critical information for understanding the evolution of this phylum, and were important constituents of marine ecosystems at this time. The well-known Chengjiang Lagerst atte (Cambrian Stage 3, c. 518 Ma) has yielded the highest known diversity of radiodonts of any Cambrian Konservat-Lagerst atten, and represents a crucial deposit for radiodont research. One important but generally overlooked Chengjiang radiodont taxon, previously identified as Anomalocaris sp. or Radiodont C, is herein designated as the type species of a new monotypic genus, Shucaris ankylosskelos gen. et sp. nov., based on dozens of specimens. Shucaris is distinctive for its combination of several characters, including the presence of two pairs of endites on its proximal-most claw podomere, posteriorly inward curved endites on claw podomeres 2-6, and, most strikingly, the coexistence of gnathobase-like structures and an oral cone. New material of Ramskoeldia consimilis records the first known oral cone in this species, confirming that oral cones and gnathobase-like structures co-occur in multiple radiodont taxa. Phylogenetic analyses retrieve Shucaris as either an early diverging member of Anomalocarididae or as sister to the clade Anomalocarididae Amplectobeluidae. Moreover, our phylogenetic analyses also support the divergence between hurdiid and non-hurdiid radiodonts.

@article{doi1010801477201920242364887,
    author = "Wu, Yu and Pates, Stephen and Liu, Cong and Zhang, Mingjing and Lin, Weiliang and Ma, Jiaxin and Wu, Yuheng and Chai, Shu and Zhang, Xingliang and Fu, Dongjing",
    title = "A new radiodont from the lower Cambrian (Series 2 Stage 3) Chengjiang Lagerstätte, South China informs the evolution of feeding structures in radiodonts",
    year = "2024",
    journal = "Journal of Systematic Palaeontology",
    abstract = "Radiodonts, a diverse clade of early Palaeozoic stem-group euarthropods, have provided critical information for understanding the evolution of this phylum, and were important constituents of marine ecosystems at this time. The well-known Chengjiang Lagerst atte (Cambrian Stage 3, c. 518 Ma) has yielded the highest known diversity of radiodonts of any Cambrian Konservat-Lagerst atten, and represents a crucial deposit for radiodont research. One important but generally overlooked Chengjiang radiodont taxon, previously identified as Anomalocaris sp. or Radiodont C, is herein designated as the type species of a new monotypic genus, Shucaris ankylosskelos gen. et sp. nov., based on dozens of specimens. Shucaris is distinctive for its combination of several characters, including the presence of two pairs of endites on its proximal-most claw podomere, posteriorly inward curved endites on claw podomeres 2-6, and, most strikingly, the coexistence of gnathobase-like structures and an oral cone. New material of Ramskoeldia consimilis records the first known oral cone in this species, confirming that oral cones and gnathobase-like structures co-occur in multiple radiodont taxa. Phylogenetic analyses retrieve Shucaris as either an early diverging member of Anomalocarididae or as sister to the clade Anomalocarididae Amplectobeluidae. Moreover, our phylogenetic analyses also support the divergence between hurdiid and non-hurdiid radiodonts.",
    url = "https://doi.org/10.1080/14772019.2024.2364887",
    doi = "10.1080/14772019.2024.2364887",
    openalex = "W4400684312",
    references = "doi101016s0748300703000604, doi101093sysbiosys029, doi101093sysbiosyy032, doi101098rstb20210034, doi101111cla12160, doi101111j109600311996tb00196x, doi101111j109600311999tb00277x, doi101111j155856461985tb00420x, doi101186s128590171934z, doi103389feart20231160285, doi105860choice334500, openalexw2611511275"
}

based on new specimens from the Burgess Shale and describe exquisitely preserved mandibles with teeth and adjacent structures: a hypostome, maxillae and potential paragnaths. These structures can be homologized with those of Cambrian fuxianhuiids and extant mandibulates, and suggest that the ancestral mandibulate head could have had a limbless segment but retained its plasticity, allowing for limb re-expression within Pancrustacea. Furthermore, we show the presence of limbs with spinose endites which created a suspension-feeding structure. This discovery provides morphological evidence for suspension feeding among large Cambrian euarthropods and evinces the increasing exploitation of planktonic resources in Cambrian pelagic food webs.

@article{doi101098rspb20240622,
    author = "Izquierdo‐López, Alejandro and Caron, Jean‐Bernard",
    title = "The Cambrian Odaraia alata and the colonization of nektonic suspension-feeding niches by early mandibulates",
    year = "2024",
    journal = "Proceedings of the Royal Society B Biological Sciences",
    abstract = "based on new specimens from the Burgess Shale and describe exquisitely preserved mandibles with teeth and adjacent structures: a hypostome, maxillae and potential paragnaths. These structures can be homologized with those of Cambrian fuxianhuiids and extant mandibulates, and suggest that the ancestral mandibulate head could have had a limbless segment but retained its plasticity, allowing for limb re-expression within Pancrustacea. Furthermore, we show the presence of limbs with spinose endites which created a suspension-feeding structure. This discovery provides morphological evidence for suspension feeding among large Cambrian euarthropods and evinces the increasing exploitation of planktonic resources in Cambrian pelagic food webs.",
    url = "https://doi.org/10.1098/rspb.2024.0622",
    doi = "10.1098/rspb.2024.0622",
    openalex = "W4400900685",
    references = "doi101098rsos191350, doi101098rsos220933"
}

Abstract Artiopoda, an early arthropod group, displays post-antennal appendages resembling trilobite limbs, but relationships with other ealy arthropods remain enigmatic. Limited studies and morphological details hinder the understanding of internal relationships within Artiopoda. Recently, exceptionally well preserved arthropod fossils from the Chengjiang Biota were studied using X-ray computed tomography, revealing detailed morphologies. In this study, Cindarella eucalla, a xandarellid from the Chengjiang Biota, was re-investigated using X-ray computed tomography and fluorescent microscopy to reconstruct its morphology and understand its phylogeny and ecology. This study successfully reconstructed a three-dimensional model of Cindarella eucalla, revealing features, such as spindle-shaped trunk tergites with the anterior six covered by the head shield and axial spines extending from the last four, natant hypostome, four post-antennal cephalic appendage pairs, dorsoventral mismatch existed between trunk tergites and limb pairs. This research suggests that Cindarella eucalla could escape in a very short time when it encounters an enemy, and it probably lived in muddy environments with ample light. Phylogenetic analysis indicates that Xandarellids may have close relationship with concililiterga or a clade composed of Nektaspida + (Conciliterga + (Phytophilaspis pergamena + Trilobita)).

@misc{doi10110120240710602865,
    author = "Zhang, Maoyin and Liu, Yu and Mai, Huijuan and Schmidt, Michel and Hou, Xianguang",
    title = "Ventral Morphology and Ecological Implications of Cindarella eucalla (Artiopoda, Xandarellida) from Chengjiang Biota, China",
    year = "2024",
    booktitle = "bioRxiv (Cold Spring Harbor Laboratory)",
    abstract = "Abstract Artiopoda, an early arthropod group, displays post-antennal appendages resembling trilobite limbs, but relationships with other ealy arthropods remain enigmatic. Limited studies and morphological details hinder the understanding of internal relationships within Artiopoda. Recently, exceptionally well preserved arthropod fossils from the Chengjiang Biota were studied using X-ray computed tomography, revealing detailed morphologies. In this study, Cindarella eucalla, a xandarellid from the Chengjiang Biota, was re-investigated using X-ray computed tomography and fluorescent microscopy to reconstruct its morphology and understand its phylogeny and ecology. This study successfully reconstructed a three-dimensional model of Cindarella eucalla, revealing features, such as spindle-shaped trunk tergites with the anterior six covered by the head shield and axial spines extending from the last four, natant hypostome, four post-antennal cephalic appendage pairs, dorsoventral mismatch existed between trunk tergites and limb pairs. This research suggests that Cindarella eucalla could escape in a very short time when it encounters an enemy, and it probably lived in muddy environments with ample light. Phylogenetic analysis indicates that Xandarellids may have close relationship with concililiterga or a clade composed of Nektaspida + (Conciliterga + (Phytophilaspis pergamena + Trilobita)).",
    url = "https://doi.org/10.1101/2024.07.10.602865",
    doi = "10.1101/2024.07.10.602865",
    openalex = "W4400618474",
    references = "doi101002spp21495, doi101186s12862021018541"
}

BACKGROUND: The early Cambrian arthropod clade Megacheira, also referred to as great appendage arthropods, comprised a group of diminutive and elongated predators during the early Palaeozoic era, around 518 million years ago. In addition to those identified in the mid-Cambrian Burgess Shale biota, numerous species are documented in the renowned 518-million-year-old Chengjiang biota of South China. Notably, one species, Tanglangia longicaudata, has remained inadequately understood due to limited available material and technological constraints. In this study, we, for the first time, examined eight fossil specimens (six individuals) utilizing state-of-the-art μCT and computer-based 3D rendering techniques to unveil the hitherto hidden ventral and appendicular morphology of this species. RESULTS: We have identified a set of slender endopodites gradually narrowing distally, along with a leaf-shaped exopodite adorned with fringed setae along its margins, and a small putative exite attached to the basipodite. Our techniques have further revealed the presence of four pairs of biramous appendages in the head, aligning with the recently reported six-segmented head in other early euarthropods. Additionally, we have discerned two peduncle elements for the great appendage. These findings underscore that, despite the morphological diversity observed in early euarthropods, there exists similarity in appendicular morphology across various groups. In addition, we critically examine the existing literature on this taxon, disentangling previous mislabelings, mentions, descriptions, and, most importantly, illustrations. CONCLUSIONS: The μCT-based investigation of fossil material of Tanglangia longicaudata, a distinctive early Cambrian euarthropod from the renowned Chengjiang biota, enhances our comprehensive understanding of the evolutionary morphology of the Megacheira. Its overall morphological features, including large cup-shaped eyes, raptorial great appendages, and a remarkably elongated telson, suggest its potential ecological role as a crepuscular predator and adept swimmer in turbid waters.

@article{doi101186s1291502401889y,
    author = "Schmidt, Michel and Hou, Xianguang and Mai, Huijuan and Zhou, Guixian and Melzer, Roland R. and Zhang, Xilin and Liu, Yu",
    title = "Unveiling the ventral morphology of a rare early Cambrian great appendage arthropod from the Chengjiang biota of China",
    year = "2024",
    journal = "BMC Biology",
    abstract = "BACKGROUND: The early Cambrian arthropod clade Megacheira, also referred to as great appendage arthropods, comprised a group of diminutive and elongated predators during the early Palaeozoic era, around 518 million years ago. In addition to those identified in the mid-Cambrian Burgess Shale biota, numerous species are documented in the renowned 518-million-year-old Chengjiang biota of South China. Notably, one species, Tanglangia longicaudata, has remained inadequately understood due to limited available material and technological constraints. In this study, we, for the first time, examined eight fossil specimens (six individuals) utilizing state-of-the-art μCT and computer-based 3D rendering techniques to unveil the hitherto hidden ventral and appendicular morphology of this species. RESULTS: We have identified a set of slender endopodites gradually narrowing distally, along with a leaf-shaped exopodite adorned with fringed setae along its margins, and a small putative exite attached to the basipodite. Our techniques have further revealed the presence of four pairs of biramous appendages in the head, aligning with the recently reported six-segmented head in other early euarthropods. Additionally, we have discerned two peduncle elements for the great appendage. These findings underscore that, despite the morphological diversity observed in early euarthropods, there exists similarity in appendicular morphology across various groups. In addition, we critically examine the existing literature on this taxon, disentangling previous mislabelings, mentions, descriptions, and, most importantly, illustrations. CONCLUSIONS: The μCT-based investigation of fossil material of Tanglangia longicaudata, a distinctive early Cambrian euarthropod from the renowned Chengjiang biota, enhances our comprehensive understanding of the evolutionary morphology of the Megacheira. Its overall morphological features, including large cup-shaped eyes, raptorial great appendages, and a remarkably elongated telson, suggest its potential ecological role as a crepuscular predator and adept swimmer in turbid waters.",
    url = "https://doi.org/10.1186/s12915-024-01889-y",
    doi = "10.1186/s12915-024-01889-y",
    openalex = "W4396227366",
    references = "doi101186s12862021018541"
}

Abstract Artiopoda, an early arthropod group, displays post-antennal appendages resembling trilobite limbs, but relationships with other ealy arthropods remain enigmatic. Limited studies and morphological details hinder the understanding of internal relationships within Artiopoda. Recently, exceptionally well preserved arthropod fossils from the Chengjiang Biota were studied using X-ray computed tomography, revealing detailed morphologies. In this study, Cindarella eucalla, a xandarellid from the Chengjiang Biota, was re-investigated using X-ray computed tomography and fluorescent microscopy to reconstruct its morphology and understand its phylogeny and ecology. This study successfully reconstructed a three-dimensional model of Cindarella eucalla, revealing features, such as spindle-shaped trunk tergites with the anterior six covered by the head shield and axial spines extending from the last four, natant hypostome, four post-antennal cephalic appendage pairs, dorsoventral mismatch existed between trunk tergites and limb pairs. This research suggests that Cindarella eucalla could escape in a very short time when it encounters an enemy, and it probably lived in muddy environments with ample light. Phylogenetic analysis indicates that Xandarellids may have close relationship with concililiterga or a clade composed of Nektaspida + (Conciliterga + (Phytophilaspis pergamena + Trilobita)).

@misc{doi107554elife100729,
    author = "Zhang, Maoyin and Liu, Yu and Mai, Huijuan and Schmidt, Michel and Hou, Xianguang",
    title = "Ventral Morphology and Ecological Implications of Cindarella eucalla (Artiopoda, Xandarellida) from Chengjiang Biota, China",
    year = "2024",
    abstract = "Abstract Artiopoda, an early arthropod group, displays post-antennal appendages resembling trilobite limbs, but relationships with other ealy arthropods remain enigmatic. Limited studies and morphological details hinder the understanding of internal relationships within Artiopoda. Recently, exceptionally well preserved arthropod fossils from the Chengjiang Biota were studied using X-ray computed tomography, revealing detailed morphologies. In this study, Cindarella eucalla, a xandarellid from the Chengjiang Biota, was re-investigated using X-ray computed tomography and fluorescent microscopy to reconstruct its morphology and understand its phylogeny and ecology. This study successfully reconstructed a three-dimensional model of Cindarella eucalla, revealing features, such as spindle-shaped trunk tergites with the anterior six covered by the head shield and axial spines extending from the last four, natant hypostome, four post-antennal cephalic appendage pairs, dorsoventral mismatch existed between trunk tergites and limb pairs. This research suggests that Cindarella eucalla could escape in a very short time when it encounters an enemy, and it probably lived in muddy environments with ample light. Phylogenetic analysis indicates that Xandarellids may have close relationship with concililiterga or a clade composed of Nektaspida + (Conciliterga + (Phytophilaspis pergamena + Trilobita)).",
    url = "https://doi.org/10.7554/elife.100729",
    doi = "10.7554/elife.100729",
    openalex = "W4403184523",
    references = "doi101002spp21495, doi101186s12862021018541"
}

Abstract Artiopoda, an early arthropod group, displays post-antennal appendages resembling trilobite limbs, but relationships with other ealy arthropods remain enigmatic. Limited studies and morphological details hinder the understanding of internal relationships within Artiopoda. Recently, exceptionally well preserved arthropod fossils from the Chengjiang Biota were studied using X-ray computed tomography, revealing detailed morphologies. In this study, Cindarella eucalla, a xandarellid from the Chengjiang Biota, was re-investigated using X-ray computed tomography and fluorescent microscopy to reconstruct its morphology and understand its phylogeny and ecology. This study successfully reconstructed a three-dimensional model of Cindarella eucalla, revealing features, such as spindle-shaped trunk tergites with the anterior six covered by the head shield and axial spines extending from the last four, natant hypostome, four post-antennal cephalic appendage pairs, dorsoventral mismatch existed between trunk tergites and limb pairs. This research suggests that Cindarella eucalla could escape in a very short time when it encounters an enemy, and it probably lived in muddy environments with ample light. Phylogenetic analysis indicates that Xandarellids may have close relationship with concililiterga or a clade composed of Nektaspida + (Conciliterga + (Phytophilaspis pergamena + Trilobita)).

@misc{doi107554elife1007291,
    author = "Zhang, Maoyin and Liu, Yu and Mai, Huijuan and Schmidt, Michel and Hou, Xianguang",
    title = "Ventral Morphology and Ecological Implications of Cindarella eucalla (Artiopoda, Xandarellida) from Chengjiang Biota, China",
    year = "2024",
    abstract = "Abstract Artiopoda, an early arthropod group, displays post-antennal appendages resembling trilobite limbs, but relationships with other ealy arthropods remain enigmatic. Limited studies and morphological details hinder the understanding of internal relationships within Artiopoda. Recently, exceptionally well preserved arthropod fossils from the Chengjiang Biota were studied using X-ray computed tomography, revealing detailed morphologies. In this study, Cindarella eucalla, a xandarellid from the Chengjiang Biota, was re-investigated using X-ray computed tomography and fluorescent microscopy to reconstruct its morphology and understand its phylogeny and ecology. This study successfully reconstructed a three-dimensional model of Cindarella eucalla, revealing features, such as spindle-shaped trunk tergites with the anterior six covered by the head shield and axial spines extending from the last four, natant hypostome, four post-antennal cephalic appendage pairs, dorsoventral mismatch existed between trunk tergites and limb pairs. This research suggests that Cindarella eucalla could escape in a very short time when it encounters an enemy, and it probably lived in muddy environments with ample light. Phylogenetic analysis indicates that Xandarellids may have close relationship with concililiterga or a clade composed of Nektaspida + (Conciliterga + (Phytophilaspis pergamena + Trilobita)).",
    url = "https://doi.org/10.7554/elife.100729.1",
    doi = "10.7554/elife.100729.1",
    openalex = "W4403184343",
    references = "doi101002spp21495, doi101186s12862021018541"
}

Abstract Pterygotids were Paleozoic marine and marginal marine large apex predatory arthropods. However, their evolution remains poorly understood due to the scarcity of their fossils and the delicate nature of their exoskeletons. The well-studied Devonian Xiaxishancun Formation in Qujing City, Yunnan, China contains various Agnatha and three eurypterid species. Our study focuses on the eurypterid material assigned to Erettopterus qujingensis Ma et al., 2022 and Pterygotus wanggaii Ma et al., 2023. The two species were discovered from the same locality, both with individuals of different developmental stages (juveniles more common), suggesting that this area could represent a breeding site, in agreement with mass molt behavior and the occurrence of other pterygotids in shallow waters. Moreover, the coexistence of heavily armed Agnatha with Pterygotus wanggaii in the Xiaxishancun Formation, alongside their robust chelicerae, supports the hypothesis that some pterygotids were piscivorous. In addition, due to ambiguity of pterygotid cheliceral dentition nomenclature, we introduce a new framework to define the cheliceral denticle types of pterygotids based on their relative positions: TD, terminal denticle; MD, median denticle (including: MMD, modified MD, and OMD, ordinary MD); BD, basal denticle. A key diagnostic feature in the cheliceral denticles of E. qujingensis is established: movable finger ends in a curved TD, 3 MMD’s present, 9 OMDs between MMD 1 and MMD 2 (OMD 4 and OMD 8 slightly enlarged); fixed finger ends in an acute TD’, 3 MMD’s present (MMD’ 2 being the largest), 8 OMD’s between MMD’ 1 and MMD’ 2 (OMD’ 5 slightly enlarged), 15 OMD’s between MMD’ 2 and MMD’ 3 (OMD’ 1 and OMD’ 10-12 slightly enlarged). This cheliceral diagnosis distinguishes E. qujingensis from Pterygotus wanggaii by its distinct number of MMDs.

@article{doi101017jpa202510135,
    author = "Wang, Maxwell and Braddy, Simon J. and Tang, Victoria and Ma, Zhiheng",
    title = "Early Devonian pterygotid eurypterids from Yunnan Province, China",
    year = "2025",
    journal = "Journal of Paleontology",
    abstract = "Abstract Pterygotids were Paleozoic marine and marginal marine large apex predatory arthropods. However, their evolution remains poorly understood due to the scarcity of their fossils and the delicate nature of their exoskeletons. The well-studied Devonian Xiaxishancun Formation in Qujing City, Yunnan, China contains various Agnatha and three eurypterid species. Our study focuses on the eurypterid material assigned to Erettopterus qujingensis Ma et al., 2022 and Pterygotus wanggaii Ma et al., 2023. The two species were discovered from the same locality, both with individuals of different developmental stages (juveniles more common), suggesting that this area could represent a breeding site, in agreement with mass molt behavior and the occurrence of other pterygotids in shallow waters. Moreover, the coexistence of heavily armed Agnatha with Pterygotus wanggaii in the Xiaxishancun Formation, alongside their robust chelicerae, supports the hypothesis that some pterygotids were piscivorous. In addition, due to ambiguity of pterygotid cheliceral dentition nomenclature, we introduce a new framework to define the cheliceral denticle types of pterygotids based on their relative positions: TD, terminal denticle; MD, median denticle (including: MMD, modified MD, and OMD, ordinary MD); BD, basal denticle. A key diagnostic feature in the cheliceral denticles of E. qujingensis is established: movable finger ends in a curved TD, 3 MMD’s present, 9 OMDs between MMD 1 and MMD 2 (OMD 4 and OMD 8 slightly enlarged); fixed finger ends in an acute TD’, 3 MMD’s present (MMD’ 2 being the largest), 8 OMD’s between MMD’ 1 and MMD’ 2 (OMD’ 5 slightly enlarged), 15 OMD’s between MMD’ 2 and MMD’ 3 (OMD’ 1 and OMD’ 10-12 slightly enlarged). This cheliceral diagnosis distinguishes E. qujingensis from Pterygotus wanggaii by its distinct number of MMDs.",
    url = "https://doi.org/10.1017/jpa.2025.10135",
    doi = "10.1017/jpa.2025.10135",
    openalex = "W4414480814",
    references = "doi101002ece311303"
}

More than half a billion years ago, a high diversity of organisms appeared in the fossil record. All major clades we know today already existed, and arthropods dominated the marine faunas. Many were already equipped with a pair of elaborated compound eyes on top of movable eye stalks. Some of them also possessed 3-4 small single-aperture eyes, so-called median eyes. Just trilobites possessed sessile dorsal eyes. One pair of compound eyes/lateral eyes is considered plesiomorphic and is a common trait for euarthropods. Here, we describe an arthropod that possessed two independent compound eye systems-a pair of stalked and a pair of tiny sessile dorsal trilobite-like compound eyes, unique in the arthropod kingdom so far. A competition between prey and predators for the capacity of vision triggered the evolution of visual systems, and we discuss this newly described system(s) in its evolutionary context and ecological significance. Regarding its eye system phylogenetically, P. daziensis reinforces the position of a now non-missing link between the non-trilobite artiopodans and trilobites.

@article{doi101038s42003025076641,
    author = "Schmidt, Michel and Schoenemann, Brigitte and Hou, Xianguang and Melzer, Roland R. and Liu, Yu",
    title = "Pygmaclypeatus daziensis, a unique lower Cambrian arthropod with two different compound eye systems",
    year = "2025",
    journal = "Communications Biology",
    abstract = "More than half a billion years ago, a high diversity of organisms appeared in the fossil record. All major clades we know today already existed, and arthropods dominated the marine faunas. Many were already equipped with a pair of elaborated compound eyes on top of movable eye stalks. Some of them also possessed 3-4 small single-aperture eyes, so-called median eyes. Just trilobites possessed sessile dorsal eyes. One pair of compound eyes/lateral eyes is considered plesiomorphic and is a common trait for euarthropods. Here, we describe an arthropod that possessed two independent compound eye systems-a pair of stalked and a pair of tiny sessile dorsal trilobite-like compound eyes, unique in the arthropod kingdom so far. A competition between prey and predators for the capacity of vision triggered the evolution of visual systems, and we discuss this newly described system(s) in its evolutionary context and ecological significance. Regarding its eye system phylogenetically, P. daziensis reinforces the position of a now non-missing link between the non-trilobite artiopodans and trilobites.",
    url = "https://doi.org/10.1038/s42003-025-07664-1",
    doi = "10.1038/s42003-025-07664-1",
    openalex = "W4407946431",
    references = "doi101186s12862021018541"
}

Much diversity in arthropod form is the result of variation in the number and differentiation of segments (tagmosis). Fossil evidence to date has suggested that the earliest-diverging arthropods, the radiodonts, exhibited comparatively limited variability in tagmosis. We present a new radiodont, Mosura fentoni n. gen. and n. sp., from the Cambrian (Wuliuan) Burgess Shale that departs from this pattern. Mosura exhibits up to 26 trunk segments, the highest number reported for any radiodont, despite being among the smallest known. The head is short, with a small, rounded preocular sclerite, three prominent eyes and appendages with curving endites tipped with paired spines, altogether suggesting a nektonic, macrophagous predatory ecology. The trunk is divided into a neck, mesotrunk with large swimming flaps and multisegmented posterotrunk with tightly spaced bands of gill lamellae and reduced flaps. Detailed preservation of expansive circulatory lacunae, closely associated with the gills, clarifies the nature of similar structures in other Cambrian arthropod fossils, including Opabinia. The morphology of the posterotrunk suggests specialization for respiration, unique among radiodonts, but broadly convergent with the xiphosuran opisthosoma, isopod pleon and hexapod abdomen. This reinforces the hypothesis that multiple arthropod lineages underwent parallel diversification in tagmosis, in tandem with their initial Cambrian radiation.

@article{doi101098rsos242122,
    author = "Moysiuk, Joseph and Caron, Jean-Bernard",
    title = "Early evolvability in arthropod tagmosis exemplified by a new radiodont from the Burgess Shale.",
    year = "2025",
    journal = "Royal Society open science",
    abstract = "Much diversity in arthropod form is the result of variation in the number and differentiation of segments (tagmosis). Fossil evidence to date has suggested that the earliest-diverging arthropods, the radiodonts, exhibited comparatively limited variability in tagmosis. We present a new radiodont, Mosura fentoni n. gen. and n. sp., from the Cambrian (Wuliuan) Burgess Shale that departs from this pattern. Mosura exhibits up to 26 trunk segments, the highest number reported for any radiodont, despite being among the smallest known. The head is short, with a small, rounded preocular sclerite, three prominent eyes and appendages with curving endites tipped with paired spines, altogether suggesting a nektonic, macrophagous predatory ecology. The trunk is divided into a neck, mesotrunk with large swimming flaps and multisegmented posterotrunk with tightly spaced bands of gill lamellae and reduced flaps. Detailed preservation of expansive circulatory lacunae, closely associated with the gills, clarifies the nature of similar structures in other Cambrian arthropod fossils, including Opabinia. The morphology of the posterotrunk suggests specialization for respiration, unique among radiodonts, but broadly convergent with the xiphosuran opisthosoma, isopod pleon and hexapod abdomen. This reinforces the hypothesis that multiple arthropod lineages underwent parallel diversification in tagmosis, in tandem with their initial Cambrian radiation.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC12076883/",
    doi = "10.1098/rsos.242122",
    pmcid = "PMC12076883",
    pmid = "40370603",
    references = "doi101098rsos220933"
}

In this study, a healthy iPSC line SDQLCHi087-A was successfully generated by reprogramming from peripheral blood mononuclear cells using integration-free episomal plasmids. The iPSC line presented a normal karyotype, expressed high levels of pluripotent markers, and exhibited the ability to differentiate to three germ layers in vitro. The cell line serves as a valuable control for studies of molecular pathogenesis and the development of disease models.

@article{doi101016jscr2026103997,
    author = "Lin, Ziming and Li, Anna and Zhang, Haiyan",
    title = "Generation of a human induced pluripotent stem cell line SDQLCHi087-A from a healthy Chinese child donor.",
    year = "2026",
    journal = "Stem cell research",
    abstract = "In this study, a healthy iPSC line SDQLCHi087-A was successfully generated by reprogramming from peripheral blood mononuclear cells using integration-free episomal plasmids. The iPSC line presented a normal karyotype, expressed high levels of pluripotent markers, and exhibited the ability to differentiate to three germ layers in vitro. The cell line serves as a valuable control for studies of molecular pathogenesis and the development of disease models.",
    url = "https://pubmed.ncbi.nlm.nih.gov/42044570/",
    doi = "10.1016/j.scr.2026.103997",
    openalex = "W7154954138",
    pmid = "42044570"
}

have been considered Cambrian stem- or crown-group chelicerates, but they all lack unequivocal chelicerae, leaving the emergence of chelicerae-bearing arthropods unclear. Here we describe Megachelicerax cousteaui gen. et sp. nov., a large soft-bodied arthropod from the middle Cambrian of Utah featuring massive three-segmented chelicerae, along with five pairs of pseudobiramous prosomal limbs with non-foliaceous exopodal rami, and plate-like lamellae-bearing opisthosomal appendages. Bayesian and parsimony phylogenetic analyses resolve Megachelicerax as a stem-group chelicerate bridging Cambrian habeliids and post-Cambrian chelicerae-bearing synziphosurines. This finding provides unequivocal evidence of large predatory chelicerates in the Cambrian, illuminates their body plan's origin, and confirms habeliids, mollisoniids and probably megacheirans as members of total-group Chelicerata.

@article{doi101038s41586026102842,
    author = "Lerosey-Aubril, Rudy and Ortega-Hernández, Javier",
    title = "A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates",
    year = "2026",
    journal = "Nature",
    abstract = "have been considered Cambrian stem- or crown-group chelicerates, but they all lack unequivocal chelicerae, leaving the emergence of chelicerae-bearing arthropods unclear. Here we describe Megachelicerax cousteaui gen. et sp. nov., a large soft-bodied arthropod from the middle Cambrian of Utah featuring massive three-segmented chelicerae, along with five pairs of pseudobiramous prosomal limbs with non-foliaceous exopodal rami, and plate-like lamellae-bearing opisthosomal appendages. Bayesian and parsimony phylogenetic analyses resolve Megachelicerax as a stem-group chelicerate bridging Cambrian habeliids and post-Cambrian chelicerae-bearing synziphosurines. This finding provides unequivocal evidence of large predatory chelicerates in the Cambrian, illuminates their body plan's origin, and confirms habeliids, mollisoniids and probably megacheirans as members of total-group Chelicerata.",
    url = "https://doi.org/10.1038/s41586-026-10284-2",
    doi = "10.1038/s41586-026-10284-2",
    openalex = "W7147179299",
    references = "doi101098rsos220933"
}

BACKGROUND: Problematic gaming and internet gaming disorder (IGD) symptoms are prevalent in adolescence, yet the longitudinal interplay between physical activity (PA), loneliness, and IGD symptoms, as well as potential sexual differences, remains unclear. OBJECTIVE: This study aimed to examine reciprocal within-person associations between PA, loneliness, and IGD symptoms among Chinese adolescent gamers and test sexual differences in these associations. METHODS: We conducted a three-wave prospective cohort study among 1332 Chinese adolescents selected using convenience sampling from five middle schools in central China who had engaged in online gaming during the previous year (n=441, 33.1%, females; mean age 3.64, SD 0.76, years). PA, loneliness, and IGD symptoms were assessed using the Physical Activity Rating Scale-3, the three-item short form of the University of California, Los Angeles Loneliness Scale, and the nine-item Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition IGD Checklist, respectively, at three 6-month intervals: wave 1 (baseline, T1), wave 2 (T2), and wave 3 (T3). A random intercept (RI) cross-lagged panel model (CLPM) and multigroup analyses were conducted. RESULTS: RI-CLPM indicated that at the within-person level, higher PA predicted decreased subsequent loneliness (T1→T2: β=-0.12, 95% CI -0.16 to -0.08; T2→T3: β=-0.13, 95% CI -0.17 to -0.08) and IGD symptoms (T1→T2: β=-0.10, 95% CI -0.16 to -0.04, P=.009; T2→T3: β=-0.10, 95% CI -0.16 to -0.04). Increased loneliness (β=-0.22, 95% CI -0.26 to -0.18) and increased IGD symptoms (β=-0.08, 95% CI -0.12 to -0.04) each predicted later reductions in PA, indicating a mutually reinforcing cycle. Increased loneliness also predicted an increase in subsequent IGD symptoms (T1→T2: β=0.14, 95% CI 0.11-0.17), and increased IGD symptoms, in turn, predicted greater loneliness in the next wave (T1→T2: β=0.18, 95% CI 0.14-0.22). Multigroup models indicated that the protective effect of PA on later loneliness and the prospective effect of loneliness on subsequent IGD symptoms were stronger among girls than boys. In males, PA significantly predicted loneliness (β=-0.08 to -0.09, 95% CI -0.15 to -0.01), and loneliness significantly predicted IGD symptoms (β=0.09, 95% CI 0.03-0.15). In females, the cross-lagged effects from PA to loneliness were significant but stronger (β=-0.17, 95% CI -0.23 to -0.11), and the paths from loneliness to later IGD symptoms were also significant (β=0.16, 95% CI 0.11-0.21). CONCLUSIONS: PA, loneliness, and IGD symptoms are reciprocally linked in adolescent gamers. By using RI-CLPM to distinguish within-person changes from stable between-person differences, this study extends prior research based mainly on cross-sectional designs or traditional CLPMs and provides a clearer understanding of the dynamic interplay among behavioral, emotional, and gaming-related factors. The findings highlight that interventions aiming to prevent IGD symptoms should simultaneously promote PA and reduce loneliness, with particular attention to sex-specific patterns, especially in girls.

@article{doi10219687847,
    author = "Hu, Chang and Meng, Xuan and Wang, Xi and Huang, Jilin",
    title = "Reciprocal Within-Person Dynamics Between Internet Gaming Disorder Symptoms, Physical Activity, and Loneliness Among Chinese Adolescent Gamers: Three-Wave Prospective Cohort Study.",
    year = "2026",
    journal = "JMIR serious games",
    abstract = "BACKGROUND: Problematic gaming and internet gaming disorder (IGD) symptoms are prevalent in adolescence, yet the longitudinal interplay between physical activity (PA), loneliness, and IGD symptoms, as well as potential sexual differences, remains unclear. OBJECTIVE: This study aimed to examine reciprocal within-person associations between PA, loneliness, and IGD symptoms among Chinese adolescent gamers and test sexual differences in these associations. METHODS: We conducted a three-wave prospective cohort study among 1332 Chinese adolescents selected using convenience sampling from five middle schools in central China who had engaged in online gaming during the previous year (n=441, 33.1\%, females; mean age 3.64, SD 0.76, years). PA, loneliness, and IGD symptoms were assessed using the Physical Activity Rating Scale-3, the three-item short form of the University of California, Los Angeles Loneliness Scale, and the nine-item Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition IGD Checklist, respectively, at three 6-month intervals: wave 1 (baseline, T1), wave 2 (T2), and wave 3 (T3). A random intercept (RI) cross-lagged panel model (CLPM) and multigroup analyses were conducted. RESULTS: RI-CLPM indicated that at the within-person level, higher PA predicted decreased subsequent loneliness (T1→T2: β=-0.12, 95\% CI -0.16 to -0.08; T2→T3: β=-0.13, 95\% CI -0.17 to -0.08) and IGD symptoms (T1→T2: β=-0.10, 95\% CI -0.16 to -0.04, P=.009; T2→T3: β=-0.10, 95\% CI -0.16 to -0.04). Increased loneliness (β=-0.22, 95\% CI -0.26 to -0.18) and increased IGD symptoms (β=-0.08, 95\% CI -0.12 to -0.04) each predicted later reductions in PA, indicating a mutually reinforcing cycle. Increased loneliness also predicted an increase in subsequent IGD symptoms (T1→T2: β=0.14, 95\% CI 0.11-0.17), and increased IGD symptoms, in turn, predicted greater loneliness in the next wave (T1→T2: β=0.18, 95\% CI 0.14-0.22). Multigroup models indicated that the protective effect of PA on later loneliness and the prospective effect of loneliness on subsequent IGD symptoms were stronger among girls than boys. In males, PA significantly predicted loneliness (β=-0.08 to -0.09, 95\% CI -0.15 to -0.01), and loneliness significantly predicted IGD symptoms (β=0.09, 95\% CI 0.03-0.15). In females, the cross-lagged effects from PA to loneliness were significant but stronger (β=-0.17, 95\% CI -0.23 to -0.11), and the paths from loneliness to later IGD symptoms were also significant (β=0.16, 95\% CI 0.11-0.21). CONCLUSIONS: PA, loneliness, and IGD symptoms are reciprocally linked in adolescent gamers. By using RI-CLPM to distinguish within-person changes from stable between-person differences, this study extends prior research based mainly on cross-sectional designs or traditional CLPMs and provides a clearer understanding of the dynamic interplay among behavioral, emotional, and gaming-related factors. The findings highlight that interventions aiming to prevent IGD symptoms should simultaneously promote PA and reduce loneliness, with particular attention to sex-specific patterns, especially in girls.",
    url = "https://pubmed.ncbi.nlm.nih.gov/42044501/",
    doi = "10.2196/87847",
    pmid = "42044501"
}