Ischigualasto formation

@misc{reig1963la2,
    author = "Reig, O. A",
    title = {La presencia de dinosaurios en los "Estratos de Ischigualastro" (Mesotriasico Superior) de las provincias de San Juan y la Rioja},
    year = "1963",
    howpublished = "Ameghiniana, v. 3, p. 1-20",
    note = {talkorigins\_source = {true}; raw\_reference = {Reig, O. A., 1963, La presencia de dinosaurios en los "Estratos de Ischigualastro" (Mesotriasico Superior) de las provincias de San Juan y la Rioja: Ameghiniana, v. 3, p. 1-20.}}
}

@misc{novas1987un1,
    author = "Novas, F",
    title = "Un probable teropodo (Saurisquia) de la Formacion Ischigualasto (Triasico Superior), San Juan, Argentina",
    year = "1987",
    howpublished = "IV Congress Argentino de Paleontologia Biostratigraphica, v. 2, p. 1-6",
    note = "talkorigins\_source = {true}; raw\_reference = {Novas, F., 1987, Un probable teropodo (Saurisquia) de la Formacion Ischigualasto (Triasico Superior), San Juan, Argentina: IV Congress Argentino de Paleontologia Biostratigraphica, v. 2, p. 1-6.}"
}

Two skulls representing new forms of carnivorous cynodonts were discovered recently in the Upper Triassic (Carnian) Ischigualasto Formation of northwestern Argentina. These specimens are the first complete carnivorous cynodonts described from the Late Triassic of Argentina, and provide critical evidence for the evolution of cranial form between well known Middle Triassic cynodonts, such as Probainognathus, and the first mammals in the latest Triassic. The first skull (PVSJ 422) is proportionately long, with a posterior skull width only 35 per cent of basal skull length (9.5 cm.). Other distinctive features of the skull include the form of the postcanine crowns, which have two cusps posterior to the principal cusp and fine serations on their leading edges, and which overlap each other in an imbricate pattern. Postcanines 5-7 are subequal in size, overlap the dentary laterally, and are substantially larger than postcanines 2-4. The dental formula in the upper jaw is I4-C1-PC7, with the small first postcanine separated fore and aft by small diastemas. As in other advanced eucynodonts, no pineal foramen is present. Some postcranial elements, as yet unstudied, were also found with this specimen. The second skull (PVSJ 411) has broader proportions, the width between quadrates almost half that of basal skull length (7.5 cm.). These proportions, in combination with deep, curved zygomatic arches, resemble other Middle Triassic cynodonts such as Probelesodon. Distinctive features of this skull include bicusped postcanines in the upper jaw similar to those of Probelesodon, and a mandibular symphysis that extends back to the level of the fourth postcanine. The dental formula in the upper jaw is I4-C1-PC6. As in the first skull, a pineal foramen is absent. Several advanced cranial features, such as a fused mandibular symphysis, occur in both skulls and strongly suggest that these new forms belong within the Eucynodontia (Hopson, 1991). Other advanced features, such as the absence of a pineal foramen, further suggest that these new forms are closer to mammals than are traversodontid cynodonts. In contrast, other characters appear to be curiosly primitive, such as a short hard palate in the first skull. These new cynodonts thus may introduce previously unseen features and character combinations to the study of cynodont cranial evolution.

@article{martínez1992two,
    author = "Martínez, Ricardo N. and Forster, Catherine A. and May, Cathleen L.",
    title = "Two new carnivorous cynodonts from the Ischigualasto Formation (Upper Triassic) of Argentina",
    year = "1992",
    journal = "The Paleontological Society Special Publications",
    abstract = "Two skulls representing new forms of carnivorous cynodonts were discovered recently in the Upper Triassic (Carnian) Ischigualasto Formation of northwestern Argentina. These specimens are the first complete carnivorous cynodonts described from the Late Triassic of Argentina, and provide critical evidence for the evolution of cranial form between well known Middle Triassic cynodonts, such as Probainognathus, and the first mammals in the latest Triassic. The first skull (PVSJ 422) is proportionately long, with a posterior skull width only 35 per cent of basal skull length (9.5 cm.). Other distinctive features of the skull include the form of the postcanine crowns, which have two cusps posterior to the principal cusp and fine serations on their leading edges, and which overlap each other in an imbricate pattern. Postcanines 5-7 are subequal in size, overlap the dentary laterally, and are substantially larger than postcanines 2-4. The dental formula in the upper jaw is I4-C1-PC7, with the small first postcanine separated fore and aft by small diastemas. As in other advanced eucynodonts, no pineal foramen is present. Some postcranial elements, as yet unstudied, were also found with this specimen. The second skull (PVSJ 411) has broader proportions, the width between quadrates almost half that of basal skull length (7.5 cm.). These proportions, in combination with deep, curved zygomatic arches, resemble other Middle Triassic cynodonts such as Probelesodon. Distinctive features of this skull include bicusped postcanines in the upper jaw similar to those of Probelesodon, and a mandibular symphysis that extends back to the level of the fourth postcanine. The dental formula in the upper jaw is I4-C1-PC6. As in the first skull, a pineal foramen is absent. Several advanced cranial features, such as a fused mandibular symphysis, occur in both skulls and strongly suggest that these new forms belong within the Eucynodontia (Hopson, 1991). Other advanced features, such as the absence of a pineal foramen, further suggest that these new forms are closer to mammals than are traversodontid cynodonts. In contrast, other characters appear to be curiosly primitive, such as a short hard palate in the first skull. These new cynodonts thus may introduce previously unseen features and character combinations to the study of cynodont cranial evolution.",
    url = "https://doi.org/10.1017/s2475262200007620",
    doi = "10.1017/s2475262200007620",
    pages = "202-202",
    volume = "6"
}

The oldest-known dinosaurs (Herrerasaurus, Pisanosaurus) occur within the Ischigualasto Formation. Recent work in the formation has brought to light significant new material, including the complete skeleton of a new primitive dinosaur. We sketch below the paleoenvironment and faunal succession during the range of these early dinosaurs, and review some of the taphonomic factors that shaped their fossil record. The Ischigualasto Formation (Carnian?) is included within the Agua de la Peña Group, a series of continental Triassic deposits exposed in the Ischigualasto-Ville Union Basin of northwest Argentina. Ischigualasto sediments rest unconformably upon the carbonaceous fluvial/lacustrine Los Rastros Formation; this contact is characterized locally by marked angular discordance. The upper contact is gradational into red-beds of the Los Colorados Formation. Medium- to coarse-grained conglomeratic sandstones, siltstones, and silty mudstones dominate the section. Sand bodies are characterized by medium- to large-scale trough cross-stratification and broad lenticular/narrow sheet geometries, and are interpreted as deposits of shallow, low-sinuosity streams. Siltstones and mudstones show pervasive evidence of soil development, including root traces, nodular caliche horizons, and pedogenic slickensides. Deposits attributable to lacustrine/paludal sedimentation are scarce, and freshwater vertebrates and invertebrates are extremely rare. These data suggest an upland depositional setting on a low-relief alluvial plain with seasonal climate. The Ischigualasto vertebrate fauna includes archosaurs, rhynchosaurs, traversodontid and carnivorous cynodonts, and temnospondyl amphibians. Rhynchosaurs dominate (relative specimen abundance) in the lower half of the section, but are absent from the upper half. Traversodontid cynodonts occur throughout the formation, but are much more abundant up-section. Archosaurs, carnivorous cynodonts, and particularly temnospondyls are rare throughout, with dinosaurs limited to the lower half. No major stratigraphic or sedimentologic changes occur up-section, and there is no evidence for significant shifts in physical or chemical taphonomic processes. Thus, trends in relative taxon abundance likely record a true biotic signal (e.g., local extinction, immigration) rather than a taphonomically-driven preservational bias. Fossils are preserved as isolated carcasses or disarticulated elements, most often in fine-grained overbank facies. Bone beds and microsites are conspicuously absent. Temnospondyl remains were found within a local carbonaceous lens developed upon a sand body, suggesting autochthonous burial in an abandoned-channel setting. Isolated skulls, particularly those of the traversodontid Exaeretodon, are extremely common. Fifteen isolated crania of this cynodont were mapped in a single stratum with limited areal exposure. Abundant preservation of isolated therapsid crania has also been reported in the Beaufort Series (Permo-Triassic) of the Karoo Basin, South Africa (Smith, 1980). Post-disarticulation hydrodynamic sorting (enhanced by scavenging?) of an areally dispersed mass-mortality assemblage may explain this unusual occurrence.

@article{rogers1992paleoenvironment,
    author = "Rogers, Raymond R. and Forster, Catherine A. and May, Cathleen L. and Monetta, Alfredo and Sereno, Paul C.",
    title = "Paleoenvironment and taphonomy of the dinosaur-bearing Ischigualasto Formation (Upper Triassic, Argentina)",
    year = "1992",
    journal = "The Paleontological Society Special Publications",
    abstract = "The oldest-known dinosaurs (Herrerasaurus, Pisanosaurus) occur within the Ischigualasto Formation. Recent work in the formation has brought to light significant new material, including the complete skeleton of a new primitive dinosaur. We sketch below the paleoenvironment and faunal succession during the range of these early dinosaurs, and review some of the taphonomic factors that shaped their fossil record. The Ischigualasto Formation (Carnian?) is included within the Agua de la Peña Group, a series of continental Triassic deposits exposed in the Ischigualasto-Ville Union Basin of northwest Argentina. Ischigualasto sediments rest unconformably upon the carbonaceous fluvial/lacustrine Los Rastros Formation; this contact is characterized locally by marked angular discordance. The upper contact is gradational into red-beds of the Los Colorados Formation. Medium- to coarse-grained conglomeratic sandstones, siltstones, and silty mudstones dominate the section. Sand bodies are characterized by medium- to large-scale trough cross-stratification and broad lenticular/narrow sheet geometries, and are interpreted as deposits of shallow, low-sinuosity streams. Siltstones and mudstones show pervasive evidence of soil development, including root traces, nodular caliche horizons, and pedogenic slickensides. Deposits attributable to lacustrine/paludal sedimentation are scarce, and freshwater vertebrates and invertebrates are extremely rare. These data suggest an upland depositional setting on a low-relief alluvial plain with seasonal climate. The Ischigualasto vertebrate fauna includes archosaurs, rhynchosaurs, traversodontid and carnivorous cynodonts, and temnospondyl amphibians. Rhynchosaurs dominate (relative specimen abundance) in the lower half of the section, but are absent from the upper half. Traversodontid cynodonts occur throughout the formation, but are much more abundant up-section. Archosaurs, carnivorous cynodonts, and particularly temnospondyls are rare throughout, with dinosaurs limited to the lower half. No major stratigraphic or sedimentologic changes occur up-section, and there is no evidence for significant shifts in physical or chemical taphonomic processes. Thus, trends in relative taxon abundance likely record a true biotic signal (e.g., local extinction, immigration) rather than a taphonomically-driven preservational bias. Fossils are preserved as isolated carcasses or disarticulated elements, most often in fine-grained overbank facies. Bone beds and microsites are conspicuously absent. Temnospondyl remains were found within a local carbonaceous lens developed upon a sand body, suggesting autochthonous burial in an abandoned-channel setting. Isolated skulls, particularly those of the traversodontid Exaeretodon, are extremely common. Fifteen isolated crania of this cynodont were mapped in a single stratum with limited areal exposure. Abundant preservation of isolated therapsid crania has also been reported in the Beaufort Series (Permo-Triassic) of the Karoo Basin, South Africa (Smith, 1980). Post-disarticulation hydrodynamic sorting (enhanced by scavenging?) of an areally dispersed mass-mortality assemblage may explain this unusual occurrence.",
    url = "https://doi.org/10.1017/s2475262200008091",
    doi = "10.1017/s2475262200008091",
    pages = "249-249",
    volume = "6"
}

40 Ar/ 39 Ar dating of sanidine from a bentonite interbedded in the Ischigualasto Formation of northwestern Argentina yielded a plateau age of 227.8 ± 0.3 million years ago. This middle Carnian age is a direct calibration of the Ischigualasto tetrapod assemblage, which includes some of the best known early dinosaurs. This age shifts last appearances of Ischigualasto taxa back into the middle Carnian, diminishing the magnitude of the proposed late Carnian tetrapod extinction event. By 228 million years ago, the major dinosaurian lineages were established, and theropods were already important constituents of the carnivorous tetrapod guild in the Ischigualasto—Villa Unión Basin. Dinosaurs as a whole remained minor components of tetrapod faunas for at least another 10 million years.

@article{doi101126science2605109794,
    author = "Rogers, Raymond R. and Swisher, Carl C. and Sereno, Paul C. and Monetta, Alfredo M. and Forster, Catherine A. and Martínez, Ricardo N.",
    title = "The Ischigualasto Tetrapod Assemblage (Late Triassic, Argentina) and 40 Ar/ 39 Ar Dating of Dinosaur Origins",
    year = "1993",
    journal = "Science",
    abstract = "40 Ar/ 39 Ar dating of sanidine from a bentonite interbedded in the Ischigualasto Formation of northwestern Argentina yielded a plateau age of 227.8 ± 0.3 million years ago. This middle Carnian age is a direct calibration of the Ischigualasto tetrapod assemblage, which includes some of the best known early dinosaurs. This age shifts last appearances of Ischigualasto taxa back into the middle Carnian, diminishing the magnitude of the proposed late Carnian tetrapod extinction event. By 228 million years ago, the major dinosaurian lineages were established, and theropods were already important constituents of the carnivorous tetrapod guild in the Ischigualasto—Villa Unión Basin. Dinosaurs as a whole remained minor components of tetrapod faunas for at least another 10 million years.",
    url = "https://doi.org/10.1126/science.260.5109.794",
    doi = "10.1126/science.260.5109.794",
    openalex = "W2017250743",
    references = "doi101007bf01134434, doi101111j155856461971tb01922x, doi1023073514444, doi1023073514695, doi105962bhlpart22965, openalexw1574544995"
}

ABSTRACT Herrerasauridae from the Ischigualasto Formation (San Juan Province, Argentina) included Herrerasaurus ischigualastensis Reig, 1963, Ischisaurus cattoi Reig, 1963, and Frenguellisaurus ischigualastensis Novas, 1986. Review of type and referred specimens of those taxa suggests that Ischisaurus and Frenguellisaurus are junior synonyms of Herrerasaurus. At present, Herrerasaurus is the only Herrerasauridae documented in the Ischigualasto Formation, and the record of a cf. Staurikosaurus in those beds is here dismissed. Cladistic analysis counters previous hypotheses supporting the outgroup position of Herrerasauridae with respect to the remaining dinosaurs. Instead, new evidence supports this group as saurischian dinosaurs: the posterior process of the jugal is forked, a hyposphene-hypantrum articulation is present in dorsal vertebrae, the distal shaft of the ischium is rod-like, and six other saurischian synapomorphies are present. Moreover, herrerasaurids share with other theropods 11 synapomorphies including prong-shaped epipophyses on the cervical vertebrae, elongate prezygapophyses in distal caudals, humerus nearly 50% of femoral length, strongly reduced metacarpals IV and V, and distally enlarged pubis. In the context of the hypothesis accepted here, the presence of two sacral vertebrae and absence of a brevis fossa on the ilium in the Herrerasauridae are interpreted as apomorphic reversals within Dinosauria.

@article{doi10108002724634199410011523,
    author = "Novas, Fernando E.",
    title = "New information on the systematics and postcranial skeleton of Herrerasaurus ischigualastensis (Theropoda: Herrerasauridae) from the Ischigualasto Formation (Upper Triassic) of Argentina",
    year = "1994",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT Herrerasauridae from the Ischigualasto Formation (San Juan Province, Argentina) included Herrerasaurus ischigualastensis Reig, 1963, Ischisaurus cattoi Reig, 1963, and Frenguellisaurus ischigualastensis Novas, 1986. Review of type and referred specimens of those taxa suggests that Ischisaurus and Frenguellisaurus are junior synonyms of Herrerasaurus. At present, Herrerasaurus is the only Herrerasauridae documented in the Ischigualasto Formation, and the record of a cf. Staurikosaurus in those beds is here dismissed. Cladistic analysis counters previous hypotheses supporting the outgroup position of Herrerasauridae with respect to the remaining dinosaurs. Instead, new evidence supports this group as saurischian dinosaurs: the posterior process of the jugal is forked, a hyposphene-hypantrum articulation is present in dorsal vertebrae, the distal shaft of the ischium is rod-like, and six other saurischian synapomorphies are present. Moreover, herrerasaurids share with other theropods 11 synapomorphies including prong-shaped epipophyses on the cervical vertebrae, elongate prezygapophyses in distal caudals, humerus nearly 50\% of femoral length, strongly reduced metacarpals IV and V, and distally enlarged pubis. In the context of the hypothesis accepted here, the presence of two sacral vertebrae and absence of a brevis fossa on the ilium in the Herrerasauridae are interpreted as apomorphic reversals within Dinosauria.",
    url = "https://doi.org/10.1080/02724634.1994.10011523",
    doi = "10.1080/02724634.1994.10011523",
    openalex = "W2050709074",
    references = "crossref1976allosaurus, doi101007bf02985709, doi101007bf02986571, doi101017s247526300000091x, doi10108002724634199010011815, doi10108002724634199110011426, doi101111j109583121965tb00944x, doi101126science10246376, doi105281zenodo16120887, doi105281zenodo16171435, doi105281zenodo16692311, doi105479si00963801361666197, doi105962p226819, doi105962p234849, doi105962p313819, galton1977onstaurikosaums, openalexw1594077233, openalexw3140893762, openalexw53287739"
}

ABSTRACT The nearly complete skull of a recently discovered carnivorous eucynodont, Ecteninion lunensis, gen. et sp. nov., is described. This is the first new genus of carnivorous cynodont reported from the Late Triassic (middle Carnian) Ischigualasto Formation of northwestern Argentina, and is unique to the formation. Diagnostic features include partially differentiated cheek teeth that overlap in an imbricate pattern, elongate braincase and parietal crest, pronounced lateral expansion of the braincase, sagittal crest that overhangs the occipital plate in dorsal view, gracile postorbital bars, short osseous secondary palate, maxilla excluded from the border of the subtemporal fenestra, palatine and orbitosphenoid that contribute to the medial orbital wall, post-temporal foramen enclosed within the tabular, squamosals that nearly meet at the posterior end of the sagittal crest, narrow and deep groove for the external auditory meatus, jaw articulation located at the anterior base of the zygomatic arches, and cavum epiptericum extensively floored by the prootic. A phylogenetic analysis of the Eucynodontia, using craniodental characters, places Ecteninion lunensis in a trichotomy with Probainognathus and a monophyletic clade consisting of Tritylodontidae, Tritheledontidae, and Morganucodon.

@article{doi10108002724634199610011314,
    author = "Martínez, Ricardo N. and May, Cathleen L. and Forster, Catherine A.",
    title = "A new carnivorous cynodont from the Ischigualasto Formation (Late Triassic, Argentina), with comments on eucynodont phylogeny",
    year = "1996",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT The nearly complete skull of a recently discovered carnivorous eucynodont, Ecteninion lunensis, gen. et sp. nov., is described. This is the first new genus of carnivorous cynodont reported from the Late Triassic (middle Carnian) Ischigualasto Formation of northwestern Argentina, and is unique to the formation. Diagnostic features include partially differentiated cheek teeth that overlap in an imbricate pattern, elongate braincase and parietal crest, pronounced lateral expansion of the braincase, sagittal crest that overhangs the occipital plate in dorsal view, gracile postorbital bars, short osseous secondary palate, maxilla excluded from the border of the subtemporal fenestra, palatine and orbitosphenoid that contribute to the medial orbital wall, post-temporal foramen enclosed within the tabular, squamosals that nearly meet at the posterior end of the sagittal crest, narrow and deep groove for the external auditory meatus, jaw articulation located at the anterior base of the zygomatic arches, and cavum epiptericum extensively floored by the prootic. A phylogenetic analysis of the Eucynodontia, using craniodental characters, places Ecteninion lunensis in a trichotomy with Probainognathus and a monophyletic clade consisting of Tritylodontidae, Tritheledontidae, and Morganucodon.",
    url = "https://doi.org/10.1080/02724634.1996.10011314",
    doi = "10.1080/02724634.1996.10011314",
    openalex = "W2032431312",
    references = "martínez1992two"
}

ABSTRACT A new species of Probelesodon, P. sanjuanensis, from the Late Triassic (middle Carnian) Ischigualasto Formation of Argentina is described Diagnostic characters include: six postcanine teeth, highly arched zygomatic arch, well developed squamosal-surangular articulation, very deep dentary with a strong posteroventral angle, and widely separated postorbitals. Probelesodon is also united as a monophyletic taxon. The presence of Probelesodon in the Ischigualasto Formation significantly extends the range of this genus from the Ladinian (Chañares Formation) into the middle Carnian.

@article{doi10108002724634199610011315,
    author = "Martínez, Ricardo N. and Forster, Catherine A.",
    title = "The skull of Probelesodon sanjuanensis, sp. nov., from the Late Triassic Ischigualasto Formation of Argentina",
    year = "1996",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT A new species of Probelesodon, P. sanjuanensis, from the Late Triassic (middle Carnian) Ischigualasto Formation of Argentina is described Diagnostic characters include: six postcanine teeth, highly arched zygomatic arch, well developed squamosal-surangular articulation, very deep dentary with a strong posteroventral angle, and widely separated postorbitals. Probelesodon is also united as a monophyletic taxon. The presence of Probelesodon in the Ischigualasto Formation significantly extends the range of this genus from the Ladinian (Chañares Formation) into the middle Carnian.",
    url = "https://doi.org/10.1080/02724634.1996.10011315",
    doi = "10.1080/02724634.1996.10011315",
    openalex = "W1992706854",
    references = "martínez1992two, rogers1992paleoenvironment"
}

@article{doi101016jgeobios200304008,
    author = "Arcucci, Andrea B. and Marsicano, Claudia A. and Caselli, Alberto",
    title = "Tetrapod association and palaeoenvironment of the Los Colorados Formation (Argentina): a significant sample from Western Gondwana at the end of the Triassic",
    year = "2004",
    journal = "Geobios",
    url = "https://doi.org/10.1016/j.geobios.2003.04.008",
    doi = "10.1016/j.geobios.2003.04.008",
    openalex = "W1989713280",
    references = "crossref1998encyclopedia, doi101016s0031018298001175, doi1023073514751, doi1023073514816, doi1025249037575361988182172190, doi105860choice273305, doi105860choice304391, doi105860choice325663, openalexw114509570, walker1964triassic"
}

Resumen. En el cerro Las Chilcas y el anticlinal el Cholo, ubicados en el tramo superior del valle del rio Atuel, sudoeste de la provincia de Mendoza, Argentina, se relevaron tres perfiles sedimentologicos de detalle en secciones correspondientes a la Formacion El Freno (Sinemuriano). La Formacion El Freno esta compuesta por una compleja asociacion de conglomerados clasto-soportados, areniscas conglomeradicas, areniscas, fangolitas y niveles heteroliticos. Sobre la base de las texturas y estructuras primarias y de las proporciones entre tipos litologicos se definen diversas asociaciones de facies silicoclasticas que permiten interpretar al conjunto como originado en sistemas fluviales de carga traccional y de carga mixta, los ultimos con cuerpos de canales avulsivos con diseno en faja y cordoniforme. El desarrollo de los distintos modelos de sedimentacion fluvial es atribuido a variaciones regionales y verticales en acomodacion, aportes detriticos, descarga y pendiente regional. En los perfiles relevados se determino la existencia de seis estratos con plantas fosiles, uno de los cuales corresponde al identificado por Borrello y estudiado por Herbst. El estudio del material paleobotanico muestreado durante los relevamientos geologicos, asi como el recolectado por Borrello, permitio confeccionar una lista floristica que incluye 13 taxones: Equisetites sp., Marattia munsteri (Goeppert) Zeiller, Cladophlebis mendozaensis (Geinitz) Frenguelli, Cladophlebisugartei Herbst, Dictyophyllum (D.) atuelense Herbst, Dejerseya lobata (Jones y de Jersey) Herbst, Archangelskya proto-loxsoma (Kurtz) Herbst, Sagenopteris sp. cf. S. rhoifolia Presl, Kurtziana brandmayri Frenguelli, Otozamites bechei Brongniart, O. hislopi (Oldham) Feistmantel, Taeniopteris sp.b. y Elatocladus conferta (Oldham y Morris) Halle. Se establece el contenido paleofloristico de la Formacion El Freno en el area del tramo superior del rio Atuel, para lo cual se adiciona la lista floristica del cerro La Brea. Se compara esta asociacion de plantas fosiles con otras del Jurasico de la Argentina; este analisis ha permitido encontrar una importante similitud entre las paleofloras de la Formacion El Freno y las de la Formacion Nestares (Jurasico Temprano), aflorante en el sector noroccidental del Macizo Norpatagonico. Abstract. CONTRIBUTION TO THE SEDIMENTOLOGICAL AND PALAEOBOTANICAL KNOWLEDGE OF THE EL FRENO FORMATION (EARLY JURASSIC) IN THEUPPER ATUEL RIVER VALLEY, MENDOZA, ARGENTINA. Three detailed stratigraphic logs form the siliciclastic deposits belonging to the El Freno Formation (Sinemurian) have been measured at Las Chilcas Hill and at El Cholo Anticline (upper reaches of the Atuel River Valley, Andean Cordillera of Mendoza, Argentina). The El Freno Formation is composed of clast-supported conglomerates, gravelly sandstones, sandstones, mudstones and heterolithic levels. The El Freno deposits were formed in fluvial systems which were characterised by systematic changes in architectural style due to vertical and regional variations in accommodation space, clastic supply, discharge and regional slope. Tractional bedload systems and mixed-load systems have been recognized. The former are characterised by vertical and lateral stacking of clast-supported coarse-grained deposits with common transitional flow-regime and low flow-regime tractional structures. The mixed-load systems consist of repeated cycles of channel-fill and aggradational flood plain deposits. Two main types of palaeochannel geometries (strings and belts) have been distinguished in the mixed-load systems. Six plantiferous levels have been identified in the measured profiles. One of them had been previously defined by Borrello and studied by Herbst. The floral assemblage of the El Freno Formation is composed of 13 taxa: Equisetites sp., Marattia munsteri (Goeppert) Zeiller, Cladophlebis mendozaensis (Geinitz) Frenguelli, Cladophlebis ugartei Herbst, Dictyophyllum (D.) atuelense Herbst, Dejerseya lobata (Jones and de Jersey) Herbst, Archangelskya proto-loxsoma (Kurtz) Herbst, Sagenopteris sp. cf. S. rhoifolia Presl, Kurtziana brandmayri Frenguelli, Otozamites bechei Brongniart, O. hislopi (Oldham) Feistmantel, Taeniopteris sp.b. and Elatocladus conferta (Oldham and Morris) Halle. This study, combined with the palaeobotanical analysis of five plantiferous levels in the cerro La Brea section, allowed us to define the overall palaeofloristic composition of the El Freno Formation. The El Freno palaeoflora was compared with other Jurassic palaeofloras of Argentina. A close relationship between the floristic assemblages of the El Freno Formation and the Lower Jurassic Nestares Formation (located in the northwestern sector of the North Patagonian Massif) has been established.

@article{s2df610c785405da356bd7e4752434e149ae3c07bf,
    author = "Spalletti, L. and Morel, E. and Franzese, Juan R. and Artabe, A. and Ganuza, D. and Zúñiga, A.",
    title = "Contribución al conocimiento sedimentológico y paleobotánico de la Formación El Freno (Jurásico temprano) en el valle superior del río Atuel, Mendoza, Argentina",
    year = "2007",
    journal = "Ameghiniana",
    abstract = "Resumen. En el cerro Las Chilcas y el anticlinal el Cholo, ubicados en el tramo superior del valle del rio Atuel, sudoeste de la provincia de Mendoza, Argentina, se relevaron tres perfiles sedimentologicos de detalle en secciones correspondientes a la Formacion El Freno (Sinemuriano). La Formacion El Freno esta compuesta por una compleja asociacion de conglomerados clasto-soportados, areniscas conglomeradicas, areniscas, fangolitas y niveles heteroliticos. Sobre la base de las texturas y estructuras primarias y de las proporciones entre tipos litologicos se definen diversas asociaciones de facies silicoclasticas que permiten interpretar al conjunto como originado en sistemas fluviales de carga traccional y de carga mixta, los ultimos con cuerpos de canales avulsivos con diseno en faja y cordoniforme. El desarrollo de los distintos modelos de sedimentacion fluvial es atribuido a variaciones regionales y verticales en acomodacion, aportes detriticos, descarga y pendiente regional. En los perfiles relevados se determino la existencia de seis estratos con plantas fosiles, uno de los cuales corresponde al identificado por Borrello y estudiado por Herbst. El estudio del material paleobotanico muestreado durante los relevamientos geologicos, asi como el recolectado por Borrello, permitio confeccionar una lista floristica que incluye 13 taxones: Equisetites sp., Marattia munsteri (Goeppert) Zeiller, Cladophlebis mendozaensis (Geinitz) Frenguelli, Cladophlebisugartei Herbst, Dictyophyllum (D.) atuelense Herbst, Dejerseya lobata (Jones y de Jersey) Herbst, Archangelskya proto-loxsoma (Kurtz) Herbst, Sagenopteris sp. cf. S. rhoifolia Presl, Kurtziana brandmayri Frenguelli, Otozamites bechei Brongniart, O. hislopi (Oldham) Feistmantel, Taeniopteris sp.b. y Elatocladus conferta (Oldham y Morris) Halle. Se establece el contenido paleofloristico de la Formacion El Freno en el area del tramo superior del rio Atuel, para lo cual se adiciona la lista floristica del cerro La Brea. Se compara esta asociacion de plantas fosiles con otras del Jurasico de la Argentina; este analisis ha permitido encontrar una importante similitud entre las paleofloras de la Formacion El Freno y las de la Formacion Nestares (Jurasico Temprano), aflorante en el sector noroccidental del Macizo Norpatagonico. Abstract. CONTRIBUTION TO THE SEDIMENTOLOGICAL AND PALAEOBOTANICAL KNOWLEDGE OF THE EL FRENO FORMATION (EARLY JURASSIC) IN THEUPPER ATUEL RIVER VALLEY, MENDOZA, ARGENTINA. Three detailed stratigraphic logs form the siliciclastic deposits belonging to the El Freno Formation (Sinemurian) have been measured at Las Chilcas Hill and at El Cholo Anticline (upper reaches of the Atuel River Valley, Andean Cordillera of Mendoza, Argentina). The El Freno Formation is composed of clast-supported conglomerates, gravelly sandstones, sandstones, mudstones and heterolithic levels. The El Freno deposits were formed in fluvial systems which were characterised by systematic changes in architectural style due to vertical and regional variations in accommodation space, clastic supply, discharge and regional slope. Tractional bedload systems and mixed-load systems have been recognized. The former are characterised by vertical and lateral stacking of clast-supported coarse-grained deposits with common transitional flow-regime and low flow-regime tractional structures. The mixed-load systems consist of repeated cycles of channel-fill and aggradational flood plain deposits. Two main types of palaeochannel geometries (strings and belts) have been distinguished in the mixed-load systems. Six plantiferous levels have been identified in the measured profiles. One of them had been previously defined by Borrello and studied by Herbst. The floral assemblage of the El Freno Formation is composed of 13 taxa: Equisetites sp., Marattia munsteri (Goeppert) Zeiller, Cladophlebis mendozaensis (Geinitz) Frenguelli, Cladophlebis ugartei Herbst, Dictyophyllum (D.) atuelense Herbst, Dejerseya lobata (Jones and de Jersey) Herbst, Archangelskya proto-loxsoma (Kurtz) Herbst, Sagenopteris sp. cf. S. rhoifolia Presl, Kurtziana brandmayri Frenguelli, Otozamites bechei Brongniart, O. hislopi (Oldham) Feistmantel, Taeniopteris sp.b. and Elatocladus conferta (Oldham and Morris) Halle. This study, combined with the palaeobotanical analysis of five plantiferous levels in the cerro La Brea section, allowed us to define the overall palaeofloristic composition of the El Freno Formation. The El Freno palaeoflora was compared with other Jurassic palaeofloras of Argentina. A close relationship between the floristic assemblages of the El Freno Formation and the Lower Jurassic Nestares Formation (located in the northwestern sector of the North Patagonian Massif) has been established.",
    url = "https://www.semanticscholar.org/paper/df610c785405da356bd7e4752434e149ae3c07bf",
    is_oa = "true",
    openalex = "W1533354937",
    semanticscholar_citation_count = "20",
    semanticscholar_id = "df610c785405da356bd7e4752434e149ae3c07bf"
}

@article{currie2009stratigraphy,
    author = "Currie, Brian S. and Colombi, Carina E. and Tabor, Neil J. and Shipman, Todd C. and Montañez, Isabel P.",
    title = "Stratigraphy and architecture of the Upper Triassic Ischigualasto Formation, Ischigualasto Provincial Park, San Juan, Argentina",
    year = "2009",
    journal = "Journal of South American Earth Sciences",
    url = "https://doi.org/10.1016/j.jsames.2008.10.004",
    doi = "10.1016/j.jsames.2008.10.004",
    number = "1",
    pages = "74-87",
    volume = "27"
}

ABSTRACT The Upper Triassic (Carnian–Norian) Ischigualasto Formation has yielded a diverse vertebrate fauna that records the initial phase of dinosaur evolution. Radioisotopic dates from ash layers within the formation provide a chrono- stratigraphic framework, and stratigraphic and sedimetological studies have subdivided the formation into four members and three abundance-based biozones. We describe two new basal dinosauromorphs, an unnamed lagerpetid and a new silesaurid, Ignotosaurus fragilis, gen. et sp. nov., which increase to 29 the number of vertebrates in the Ischigualasto fauna. We provide a census of 848 fossil specimens representing 26 vertebrate taxa logged to stratigraphic intervals of 50 m. This temporally calibrated census shows that abundance and taxonomic diversity within the Ischigualasto Formation does not change suddenly but rather appears to gradually decline in response to climatic deterioration. The only abrupt shift in faunal composition occurs at the end of the second of three biozones, when the abundant cynodont Exaeretodon is replaced by the rare dicynodont Jachaleria. RESUMEN—La Formación Ischigualasto del Triásico Superior (Carniano-Noriano) ha producido una diversa fauna de vertebrados que registra la fase inicial de la evolución de los dinosaurios. Edades radioisotópicas obtenidas de capas de ceniza constituyen un marco cronoestratigráfico y estudios estratigráficos y sedimentológicos permitieron subdividir la formación en cuatro miembros y tres biozonas de abundancia. Describimos dos nuevos dinosauromorfos basales, un lagerpétido indeterminado y un nuevo silesáurido, Ignotosaurus fragilis, gen. et sp. nov., que aumentan a 29 el número de vertebrados conocidos en la fauna de Ischigualasto. Ofrecemos un censo de 848 especímenes fósiles que representan 26 taxones de vertebrados relevados a intervalos estratigráficos de 50 m. Este censo calibrado temporalmente muestra que la abundancia y la diversidad taxonómica dentro de la Formación Ischigualasto no cambian de repente, sino que parecen disminuir gradualmente en respuesta al deterioro climático. El único cambio abrupto en la composición de la fauna se produce al final de la segunda de las tres biozonas, cuando el abundante cinodonte Exaeretodon es sustituido por el escaso dicinodonte Jachaleria.

@article{doi101080027246342013818546,
    author = "Martínez, Ricardo N. and Apaldetti, Cecilia and Alcober, Oscar A. and Colombi, Carina E. and Sereno, Paul C. and Fernández, Eliana and Malnis, Paula Santi and Correa, Gustavo and Abelín, Diego",
    title = "Vertebrate succession in the Ischigualasto Formation",
    year = "2012",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT The Upper Triassic (Carnian–Norian) Ischigualasto Formation has yielded a diverse vertebrate fauna that records the initial phase of dinosaur evolution. Radioisotopic dates from ash layers within the formation provide a chrono- stratigraphic framework, and stratigraphic and sedimetological studies have subdivided the formation into four members and three abundance-based biozones. We describe two new basal dinosauromorphs, an unnamed lagerpetid and a new silesaurid, Ignotosaurus fragilis, gen. et sp. nov., which increase to 29 the number of vertebrates in the Ischigualasto fauna. We provide a census of 848 fossil specimens representing 26 vertebrate taxa logged to stratigraphic intervals of 50 m. This temporally calibrated census shows that abundance and taxonomic diversity within the Ischigualasto Formation does not change suddenly but rather appears to gradually decline in response to climatic deterioration. The only abrupt shift in faunal composition occurs at the end of the second of three biozones, when the abundant cynodont Exaeretodon is replaced by the rare dicynodont Jachaleria. RESUMEN—La Formación Ischigualasto del Triásico Superior (Carniano-Noriano) ha producido una diversa fauna de vertebrados que registra la fase inicial de la evolución de los dinosaurios. Edades radioisotópicas obtenidas de capas de ceniza constituyen un marco cronoestratigráfico y estudios estratigráficos y sedimentológicos permitieron subdividir la formación en cuatro miembros y tres biozonas de abundancia. Describimos dos nuevos dinosauromorfos basales, un lagerpétido indeterminado y un nuevo silesáurido, Ignotosaurus fragilis, gen. et sp. nov., que aumentan a 29 el número de vertebrados conocidos en la fauna de Ischigualasto. Ofrecemos un censo de 848 especímenes fósiles que representan 26 taxones de vertebrados relevados a intervalos estratigráficos de 50 m. Este censo calibrado temporalmente muestra que la abundancia y la diversidad taxonómica dentro de la Formación Ischigualasto no cambian de repente, sino que parecen disminuir gradualmente en respuesta al deterioro climático. El único cambio abrupto en la composición de la fauna se produce al final de la segunda de las tres biozonas, cuando el abundante cinodonte Exaeretodon es sustituido por el escaso dicinodonte Jachaleria.",
    url = "https://doi.org/10.1080/02724634.2013.818546",
    doi = "10.1080/02724634.2013.818546",
    openalex = "W1990982324",
    references = "currie2009stratigraphy, doi1010160016703783901205, doi101016jgca201006017, doi101016jgeobios200304008, doi101016jpalaeo201001011, doi101016s0016703799002045, doi101038163436b0, doi101080027246342013820113, doi101080147720192010484650, doi101098rspb20110410, doi101126science1154339, doi101126science1198467, doi101130b304331, doi1012063521, doi1023071005355, doi105281zenodo16171435, doi10702499798893981674001, openalexw3206657856"
}

@article{s28f0be5a0e1379aafcd76322a1db716275e02add1,
    author = "Casamiquela, R.",
    title = "UN NUEVO DINOSAURIO ORNITISQUIO TRIASICO (PISANOSAURUS MERTII; ORNITHOPODA) DE LA FORMACION ISCHIGUALASTO, ARGENTINA",
    year = "2013",
    journal = "Ameghiniana",
    url = "https://www.semanticscholar.org/paper/8f0be5a0e1379aafcd76322a1db716275e02add1",
    is_oa = "true",
    semanticscholar_citation_count = "71",
    semanticscholar_id = "8f0be5a0e1379aafcd76322a1db716275e02add1"
}

@article{s2d4298073a7db3f2bc58bdc3d2c0ee3b0ae9e2f35,
    author = "Reig, O. A.",
    title = {LA PRESENCIA DE DINOSAURIOS SAURISQUIOS EN LOS "ESTRATOS DE ISCHIGUALASTO" (MESOTRIASICO SUPERIOR) DE LAS PROVINCIAS DE SAN JUAN Y LA RIOJA (ARGENTINA)},
    year = "2013",
    journal = "Ameghiniana",
    url = "https://www.semanticscholar.org/paper/d4298073a7db3f2bc58bdc3d2c0ee3b0ae9e2f35",
    is_oa = "true",
    semanticscholar_citation_count = "71",
    semanticscholar_id = "d4298073a7db3f2bc58bdc3d2c0ee3b0ae9e2f35"
}

A measured magnetozone sequence defined by 24 sampling sites with normal polarity and 28 sites with reverse polarity characteristic magnetizations was established for the heretofore poorly age-constrained Los Colorados Formation and its dinosaur-bearing vertebrate fauna in the Ischigualasto-Villa Union continental rift basin of Argentina. The polarity pattern in this ∼600-m-thick red-bed section can be correlated to Chrons E7r to E15n of the Newark astrochronological polarity time scale. This represents a time interval from 227 to 213 Ma, indicating that the Los Colorados Formation is predominantly Norian in age, ending more than 11 My before the onset of the Jurassic. The magnetochronology confirms that the underlying Ischigualasto Formation and its vertebrate assemblages including some of the earliest known dinosaurs are of Carnian age. The oldest dated occurrences of vertebrate assemblages with dinosaurs in North America (Chinle Formation) are younger (Norian), and thus the rise of dinosaurs was diachronous across the Americas. Paleogeography of the Ischigualasto and Los Colorados Formations indicates prolonged residence in the austral temperate humid belt where a provincial vertebrate fauna with early dinosaurs may have incubated. Faunal dispersal across the Pangean supercontinent in the development of more cosmopolitan vertebrate assemblages later in the Norian may have been in response to reduced contrasts between climate zones and lowered barriers resulting from decreasing atmospheric pCO2 levels.

@article{doi101073pnas1402369111,
    author = "Kent, Dennis V. and Malnis, Paula Santi and Colombi, Carina E. and Alcober, Oscar A. and Martínez, Ricardo N.",
    title = "Age constraints on the dispersal of dinosaurs in the Late Triassic from magnetochronology of the Los Colorados Formation (Argentina)",
    year = "2014",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "A measured magnetozone sequence defined by 24 sampling sites with normal polarity and 28 sites with reverse polarity characteristic magnetizations was established for the heretofore poorly age-constrained Los Colorados Formation and its dinosaur-bearing vertebrate fauna in the Ischigualasto-Villa Union continental rift basin of Argentina. The polarity pattern in this ∼600-m-thick red-bed section can be correlated to Chrons E7r to E15n of the Newark astrochronological polarity time scale. This represents a time interval from 227 to 213 Ma, indicating that the Los Colorados Formation is predominantly Norian in age, ending more than 11 My before the onset of the Jurassic. The magnetochronology confirms that the underlying Ischigualasto Formation and its vertebrate assemblages including some of the earliest known dinosaurs are of Carnian age. The oldest dated occurrences of vertebrate assemblages with dinosaurs in North America (Chinle Formation) are younger (Norian), and thus the rise of dinosaurs was diachronous across the Americas. Paleogeography of the Ischigualasto and Los Colorados Formations indicates prolonged residence in the austral temperate humid belt where a provincial vertebrate fauna with early dinosaurs may have incubated. Faunal dispersal across the Pangean supercontinent in the development of more cosmopolitan vertebrate assemblages later in the Norian may have been in response to reduced contrasts between climate zones and lowered barriers resulting from decreasing atmospheric pCO2 levels.",
    url = "https://doi.org/10.1073/pnas.1402369111",
    doi = "10.1073/pnas.1402369111",
    openalex = "W2148235107",
    references = "currie2009stratigraphy, doi101016jearscirev201004001, doi101016jgeobios200304008, doi101017cbo9780511564413024, doi101017cbo9780511628948, doi101017s0094837300010575, doi101017s1755691011020020, doi1010292009jb007205, doi101080027246342013818546, doi101111j1365246x1980tb02601x, doi101111j1365246x1990tb05683x, doi101126science1198467, doi101126science1234204, doi101130g22967a1, doi101130g306831, doi101175jcli39901, doi101371journalpone0009329, parker2010the"
}

Ramorinoa girolae Speg. is a “vulnerable” tree endemic to Argentina. During the pre-dispersal stage, the seeds are predated by Anypsipyla univitella. The objectives of this study were to describe some reproductive parameters (size and number of fruits and seeds) of R. girolae, to quantify pre-dispersal seed loss by abortion and predation, and to test the effect on pre-dispersal seed predation of fruit production (per tree, of co-specific neighbors, and the sum of both), size of fruits, number of seeds per fruit, and number of predators per fruit. As seeds can be partially consumed by the predator, the viability of partially damaged seeds was assessed as well. At Ischigualasto Park, we sampled 17 adult trees from 3 stands spaced 4 km apart. For each focal tree, we quantified the number of co-specific neighbors and their fruits. We collected ten fruits from canopies and recorded their length and the number and states of seeds (intact, predated, and aborted). Generalized Linear Mixed Models were fitted to evaluate explanatory variables affecting the proportion of pre-dispersal predated seeds. R. girolae suffers great loss of seeds during the pre-dispersal stage, mainly by seed predation (58% of seeds). The proportion of predated seeds was most important relative to the number of predators, the number of seeds per fruit, and the size of fruits. Fruits containing more predators, more seeds, and smaller fruits had higher proportions of predated seeds. Seed abortion would not represent an important factor of seed loss (6% of seeds

@article{papú2015pre,
    author = "Papú, Sofía and Lagos Silnik, Susana and Campos, Claudia M.",
    title = "Pre- dispersal seed loss of Ramorinoa girolae (Fabaceae) in Ischigualasto Provincial Park (San Juan, Argentina",
    year = "2015",
    journal = "Boletín de la Sociedad Argentina de Botánica",
    abstract = "Ramorinoa girolae Speg. is a “vulnerable” tree endemic to Argentina. During the pre-dispersal stage, the seeds are predated by Anypsipyla univitella. The objectives of this study were to describe some reproductive parameters (size and number of fruits and seeds) of R. girolae, to quantify pre-dispersal seed loss by abortion and predation, and to test the effect on pre-dispersal seed predation of fruit production (per tree, of co-specific neighbors, and the sum of both), size of fruits, number of seeds per fruit, and number of predators per fruit. As seeds can be partially consumed by the predator, the viability of partially damaged seeds was assessed as well. At Ischigualasto Park, we sampled 17 adult trees from 3 stands spaced 4 km apart. For each focal tree, we quantified the number of co-specific neighbors and their fruits. We collected ten fruits from canopies and recorded their length and the number and states of seeds (intact, predated, and aborted). Generalized Linear Mixed Models were fitted to evaluate explanatory variables affecting the proportion of pre-dispersal predated seeds. R. girolae suffers great loss of seeds during the pre-dispersal stage, mainly by seed predation (58\% of seeds). The proportion of predated seeds was most important relative to the number of predators, the number of seeds per fruit, and the size of fruits. Fruits containing more predators, more seeds, and smaller fruits had higher proportions of predated seeds. Seed abortion would not represent an important factor of seed loss (6\% of seeds",
    url = "https://doi.org/10.31055/1851.2372.v50.n4.12917",
    doi = "10.31055/1851.2372.v50.n4.12917",
    number = "4",
    openalex = "W2403233892",
    pages = "585-594",
    volume = "50",
    references = "doi1010079781489932426, doi1010160169534794903107, doi101086282687, doi101146annurevecolsys33020602095433, doi101146annureves01110170001551, doi101146annureves02110171002341, doi101146annureves12110181001345, doi1023072285423, doi1023073802723, openalexw1581993271"
}

Neotheropoda includes the vast majority of the predatory dinosaurs and their oldest members are Late Triassic in age. The Triassic neotheropod record is restricted to North America and Europe with the exception of a few specimens from South America, which includes Zupaysaurus rougieri and Lucianovenator bonoi. Here, the South American record of the group is enriched with the description of the new genus and species Powellvenator podocitus from the middle Norian Los Colorados Formation (Ischigualasto-Villa Unión Basin) of northwestern Argentina. The new taxa are represented by previously undescribed partial hindlimbs collected by J. F. Bonaparte and associated to the hypodigm of the pseudosuchian Riojasuchus tenuisceps. In addition, a specimen originally interpreted by Bonaparte in 1972 as an indeterminate coelurosaur is here referred to the new species. Powellvenator podocitus differs from other basal dinosaurs in character-states that include an astragalus with a distinctly sigmoid posterodorsal margin and a rounded dorsal expansion on the anteromedial portion of the astragalar body in anterior view, calcaneum with a laterally projected flange, and strongly reduced shaft of metatarsal II. The phylogenetic relationships of the new species were tested in a comprehensive analyses focused on early neotheropods, which recovered Powellvenator podocitus within Coelophysoidea and as the sister-taxon of Procompsognathus triassicus and Coelophysinae. Powellvenator podocitus represents the first coelophysoid from South America together with Lucianovenator bonoi from the Marayes-El Carrizal Basin.

@article{doi105710amgh040820173100,
    author = "Ezcurra, Martín D.",
    title = "A New Early Coelophysoid Neotheropod from the Late Triassic of Northwestern Argentina",
    year = "2017",
    journal = "Ameghiniana",
    abstract = "Neotheropoda includes the vast majority of the predatory dinosaurs and their oldest members are Late Triassic in age. The Triassic neotheropod record is restricted to North America and Europe with the exception of a few specimens from South America, which includes Zupaysaurus rougieri and Lucianovenator bonoi. Here, the South American record of the group is enriched with the description of the new genus and species Powellvenator podocitus from the middle Norian Los Colorados Formation (Ischigualasto-Villa Unión Basin) of northwestern Argentina. The new taxa are represented by previously undescribed partial hindlimbs collected by J. F. Bonaparte and associated to the hypodigm of the pseudosuchian Riojasuchus tenuisceps. In addition, a specimen originally interpreted by Bonaparte in 1972 as an indeterminate coelurosaur is here referred to the new species. Powellvenator podocitus differs from other basal dinosaurs in character-states that include an astragalus with a distinctly sigmoid posterodorsal margin and a rounded dorsal expansion on the anteromedial portion of the astragalar body in anterior view, calcaneum with a laterally projected flange, and strongly reduced shaft of metatarsal II. The phylogenetic relationships of the new species were tested in a comprehensive analyses focused on early neotheropods, which recovered Powellvenator podocitus within Coelophysoidea and as the sister-taxon of Procompsognathus triassicus and Coelophysinae. Powellvenator podocitus represents the first coelophysoid from South America together with Lucianovenator bonoi from the Marayes-El Carrizal Basin.",
    url = "https://doi.org/10.5710/amgh.04.08.2017.3100",
    doi = "10.5710/amgh.04.08.2017.3100",
    openalex = "W2745900256",
    references = "doi101111cla12160, doi101111j109600311994tb00179x, doi101111j109600312003tb00376x, doi101111j10960031200800217x, doi101111j155856461985tb00420x, doi101111j155856461988tb02497x, doi1012063521, doi101371journalpone0145713, doi1016710272463420072773tclagn20co2, doi102475ajss319111253, doi105281zenodo16171435, openalexw3215057009"
}

@article{reus2017relaciones,
    author = "Reus, María L. and de los Ríos, Claudia and Peco, Begoña and Giannoni, Stella M. and Campos, Claudia M.",
    title = "Relaciones tróficas entre mamíferos herbívoros nativos y exóticos del Parque Provincial Ischigualasto (San Juan, Argentina)",
    year = "2017",
    journal = "Ecología Austral",
    url = "https://doi.org/10.25260/ea.17.27.3.0.545",
    doi = "10.25260/ea.17.27.3.0.545",
    number = "3",
    openalex = "W2774674776",
    pages = "392-403",
    volume = "27",
    references = "doi101007bf00317422, doi101007bf00323544, doi101007bf00378733, doi101007bf00378959, doi101086284369, doi101093icbicp051, doi101111j00218901200400950x, doi101163156853974x00345, doi1016441545154220020830229tdoemd20co2, doi1023071934144"
}

Ramorinoa girolae Speg. (chica) is an endemic tree species which belongs to the Argentinian xerophyte flora. This species constitutes an appreciated forest resource for local people due to its fruits (a substantial basis of the diet of local communities) and its timber (one of the hardest woods). Moreover, chica was pointed as a vulnerable species because it is a monotypic species with low abundance and a very restricted endemism (San Juan, San Luis and La Rioja provinces). There is limited information concerning the status of genetic diversity of the species. For this, we performed an exploratory analysis to characterize the genetic diversity of a natural population located near Ischigualasto Provincial Park (San Juan, Argentina) using AFLP molecular markers in 19 individuals. The genetic data were correlated with morphometric, ecological and geographical data. Our results suggest that this population exhibited a high genetic diversity (Pj=82.3%). These values also were correlated with geographical matrices, revealing that this population exhibited a particular spatial genetic structure (SGS; Mantel Test r=0.45, P<0.001) and spatial autocorrelation. In addition, values of genetic similarity among the different analyzed individuals revealed the absence of clones, suggesting a signifcant contribution of genetic variability due to sexual reproduction in the studied population.https://doi.org/10.25260/EA.18.28.3.0.604

@article{doi1025260ea182830604,
    author = "Ortiz, Noelia Rosa and Giannoni, Stella M. and Paz, Rosalía Cristina",
    title = "Estructura genética espacial y diversidad genética de una población natural de Ramorinoa girolae en la provincia de San Juan (Argentina): Un análisis exploratorio",
    year = "2018",
    journal = "Ecología Austral",
    abstract = "Ramorinoa girolae Speg. (chica) is an endemic tree species which belongs to the Argentinian xerophyte flora. This species constitutes an appreciated forest resource for local people due to its fruits (a substantial basis of the diet of local communities) and its timber (one of the hardest woods). Moreover, chica was pointed as a vulnerable species because it is a monotypic species with low abundance and a very restricted endemism (San Juan, San Luis and La Rioja provinces). There is limited information concerning the status of genetic diversity of the species. For this, we performed an exploratory analysis to characterize the genetic diversity of a natural population located near Ischigualasto Provincial Park (San Juan, Argentina) using AFLP molecular markers in 19 individuals. The genetic data were correlated with morphometric, ecological and geographical data. Our results suggest that this population exhibited a high genetic diversity (Pj=82.3\%). These values also were correlated with geographical matrices, revealing that this population exhibited a particular spatial genetic structure (SGS; Mantel Test r=0.45, P<0.001) and spatial autocorrelation. In addition, values of genetic similarity among the different analyzed individuals revealed the absence of clones, suggesting a signifcant contribution of genetic variability due to sexual reproduction in the studied population.https://doi.org/10.25260/EA.18.28.3.0.604",
    url = "https://doi.org/10.25260/ea.18.28.3.0.604",
    doi = "10.25260/ea.18.28.3.0.604",
    openalex = "W2898003469",
    references = "papú2015pre"
}

espanolEl presente estudio trata sobre la bioestratigrafia de conodontes del tramo medio-superior de la Formacion San Juan (Ordovicico Inferior-Medio), en la seccion expuesta en la quebrada Los Gatos, ubicada en la vertiente occidental del cerro Viejo de Huaco, Precordillera Central de San Juan. Los conodontes recuperados, correspondientes a 55 especies, permiten reconocer las biozonas en la seccion estudiada. El analisis bioestratigrafico posibilita agrupar asociaciones de conodontes asignables a las zonas de Oepikodus evae, Oepikodus intermedius, Baltoniodus triangularis-Tripodus laevis y Lenodus variabilis que corresponden al intervalo Floiano medio-Darriwiliano inferior. Las zonas de Baltoniodus navis y de Microzarkodina parva no se reconocen en esta seccion en virtud de la informacion insuficiente que brinda este tramo estratigrafico. En general, los niveles correspondientes a la Zona de Baltoniodus triangularis-Tripodus laevis contienen mayor cantidad de conodontes, a diferencia de los registros de otras localidades de la Precordillera. El indice de alteracion del color de conodontes representa un CAI 2-2,5, refiriendo a paleotemperaturas de soterramiento de los estratos portadores de entre 60° y 155 °C. La presencia de numerosos conodontes fragmentados, con la lamina superficial recristalizada y con sobrecrecimientos de cristales, indicaria el efecto de procesos fosildiageneticos distintivos en las calizas portadoras. El analisis de la diversidad y abundancia de generos y especies de conodontes por intervalos cronoestratigraficos presenta un gran porcentaje de taxones de distribucion cosmopolita, un 18% y 38% en comun a nivel de especie unicamente con la Provincia Norteamericana Midcontinent (PNAM), y un pequeno porcentaje con la Provincia Nord-atlantica (PNA) y endemica de la Precordillera, lo que permite aproximar una mayor afinidad paleobiogeografica de las asociaciones de conodontes recuperadas con las de la PNAM que con las de la PNA para todo el intervalo estudiado. Por otra parte, se verifica que la Precordillera es una provincia con caracteristicas propias como la identifican diversos autores. EnglishThe present study deals with the conodont biostratigraphy from the middle and upper parts of the San Juan Formation (Lower-Middle Ordovician) exposed at the Los Gatos creek section, west of the cerro Viejo de Huaco, Central Precordillera of San Juan Province. The numerous conodonts recovered, corresponding to 55 species, allow to recognize a series of biozones in the studied section. The biostratigraphic analysis carried out herein allows determining associations of conodonts assignable to the Oepikodus evae, Oepikodus intermedius, Baltoniodus triangularis-Tripodus laevis and Lenodus variabilis zones that correspond to the middle Floian to lower Darriwilian. The Baltoniodus navis and Microzarkodina parva zones were not identified due to insufficient information provided by this stratigraphic section. In general, the levels corresponding to the Baltoniodus triangularis-Tripodus laevis Zone contain more conodonts, than the records of other localities from Precordillera. These specimens are well preserved with a color alteration index (CAI) of 2-2.5, indicating overburden paleotemperatures ranging from 60° and 155° C. The large presence of fragmented conodonts, with recrystallized surfaces and crystal overgrowth, could indicate the effect of distinctive diagenetic fossil processes on the bearer limestone. The analysis of the diversity and abundance of genera and species of conodonts by chronostratigraphic intervals presents a great percentage of cosmopolitan taxa, 18% and 38% in common, at species level, only with the North-American Midcontinent Province (NAMP), and with a small percentage with the North-Atlantic Province (NAP) and the Precordillera, which allows to approximate a greater paleobiogeographic affinity of the conodonts recovered with those of the NAMP than those of the NAP for the entire interval studied. On the other hand, the Precordillera is verified as a province with its own characteristics as identified by several authors.

@article{doi105027andgeov45n23056,
    author = "Mango, Matías J. and Albanesi, G.",
    title = "Bioestratigrafía y provincialismo de conodontes del tramo medio-superior de la Formación San Juan en el cerro Viejo de Huaco, Precordillera, Argentina",
    year = "2018",
    journal = "Andean Geology",
    abstract = "espanolEl presente estudio trata sobre la bioestratigrafia de conodontes del tramo medio-superior de la Formacion San Juan (Ordovicico Inferior-Medio), en la seccion expuesta en la quebrada Los Gatos, ubicada en la vertiente occidental del cerro Viejo de Huaco, Precordillera Central de San Juan. Los conodontes recuperados, correspondientes a 55 especies, permiten reconocer las biozonas en la seccion estudiada. El analisis bioestratigrafico posibilita agrupar asociaciones de conodontes asignables a las zonas de Oepikodus evae, Oepikodus intermedius, Baltoniodus triangularis-Tripodus laevis y Lenodus variabilis que corresponden al intervalo Floiano medio-Darriwiliano inferior. Las zonas de Baltoniodus navis y de Microzarkodina parva no se reconocen en esta seccion en virtud de la informacion insuficiente que brinda este tramo estratigrafico. En general, los niveles correspondientes a la Zona de Baltoniodus triangularis-Tripodus laevis contienen mayor cantidad de conodontes, a diferencia de los registros de otras localidades de la Precordillera. El indice de alteracion del color de conodontes representa un CAI 2-2,5, refiriendo a paleotemperaturas de soterramiento de los estratos portadores de entre 60° y 155 °C. La presencia de numerosos conodontes fragmentados, con la lamina superficial recristalizada y con sobrecrecimientos de cristales, indicaria el efecto de procesos fosildiageneticos distintivos en las calizas portadoras. El analisis de la diversidad y abundancia de generos y especies de conodontes por intervalos cronoestratigraficos presenta un gran porcentaje de taxones de distribucion cosmopolita, un 18\% y 38\% en comun a nivel de especie unicamente con la Provincia Norteamericana Midcontinent (PNAM), y un pequeno porcentaje con la Provincia Nord-atlantica (PNA) y endemica de la Precordillera, lo que permite aproximar una mayor afinidad paleobiogeografica de las asociaciones de conodontes recuperadas con las de la PNAM que con las de la PNA para todo el intervalo estudiado. Por otra parte, se verifica que la Precordillera es una provincia con caracteristicas propias como la identifican diversos autores. EnglishThe present study deals with the conodont biostratigraphy from the middle and upper parts of the San Juan Formation (Lower-Middle Ordovician) exposed at the Los Gatos creek section, west of the cerro Viejo de Huaco, Central Precordillera of San Juan Province. The numerous conodonts recovered, corresponding to 55 species, allow to recognize a series of biozones in the studied section. The biostratigraphic analysis carried out herein allows determining associations of conodonts assignable to the Oepikodus evae, Oepikodus intermedius, Baltoniodus triangularis-Tripodus laevis and Lenodus variabilis zones that correspond to the middle Floian to lower Darriwilian. The Baltoniodus navis and Microzarkodina parva zones were not identified due to insufficient information provided by this stratigraphic section. In general, the levels corresponding to the Baltoniodus triangularis-Tripodus laevis Zone contain more conodonts, than the records of other localities from Precordillera. These specimens are well preserved with a color alteration index (CAI) of 2-2.5, indicating overburden paleotemperatures ranging from 60° and 155° C. The large presence of fragmented conodonts, with recrystallized surfaces and crystal overgrowth, could indicate the effect of distinctive diagenetic fossil processes on the bearer limestone. The analysis of the diversity and abundance of genera and species of conodonts by chronostratigraphic intervals presents a great percentage of cosmopolitan taxa, 18\% and 38\% in common, at species level, only with the North-American Midcontinent Province (NAMP), and with a small percentage with the North-Atlantic Province (NAP) and the Precordillera, which allows to approximate a greater paleobiogeographic affinity of the conodonts recovered with those of the NAMP than those of the NAP for the entire interval studied. On the other hand, the Precordillera is verified as a province with its own characteristics as identified by several authors.",
    url = "http://www.andeangeology.cl/index.php/revista1/article/download/V45n2-3056/pdf",
    doi = "10.5027/andgeov45n2-3056",
    is_oa = "true",
    number = "2",
    pages = "274",
    semanticscholar_citation_count = "21",
    semanticscholar_id = "c0896567072e907e42d37845ee5e8132dbb38f09",
    volume = "45"
}

Present knowledge of Late Triassic tetrapod evolution, including the rise of dinosaurs, relies heavily on the fossil-rich continental deposits of South America, their precise depositional histories and correlations. We report on an extended succession of the Ischigualasto Formation exposed in the Hoyada del Cerro Las Lajas (La Rioja, Argentina), where more than 100 tetrapod fossils were newly collected, augmented by historical finds such as the ornithosuchid Venaticosuchus rusconii and the putative ornithischian Pisanosaurus mertii. Detailed lithostratigraphy combined with high-precision U-Pb geochronology from three intercalated tuffs are used to construct a robust Bayesian age model for the formation, constraining its deposition between 230.2 ± 1.9 Ma and 221.4 ± 1.2 Ma, and its fossil-bearing interval to 229.20 + 0.11/- 0.15-226.85 + 1.45/- 2.01 Ma. The latter is divided into a lower Hyperodapedon and an upper Teyumbaita biozones, based on the ranges of the eponymous rhynchosaurs, allowing biostratigraphic correlations to elsewhere in the Ischigualasto-Villa Unión Basin, as well as to the Paraná Basin in Brazil. The temporally calibrated Ischigualasto biostratigraphy suggests the persistence of rhynchosaur-dominated faunas into the earliest Norian. Our ca. 229 Ma age assignment to Pi. mertii partially fills the ghost lineage between younger ornithischian records and the oldest known saurischians at ca. 233 Ma.

@article{doi101038s41598020678541,
    author = "Desojo, Julia B. and Fiorelli, Lucas E. and Ezcurra, Martín D. and Martinelli, Agustín G. and Ramezani, Jahandar and da Rosa, Átila Augusto Stock and von Baczko, M. Belén and Trotteyn, M. Jimena and Montefeltro, Felipe C. and Ezpeleta, Miguel and Langer, Max C.",
    title = "The Late Triassic Ischigualasto Formation at Cerro Las Lajas (La Rioja, Argentina): fossil tetrapods, high-resolution chronostratigraphy, and faunal correlations",
    year = "2020",
    journal = "Scientific Reports",
    abstract = "Present knowledge of Late Triassic tetrapod evolution, including the rise of dinosaurs, relies heavily on the fossil-rich continental deposits of South America, their precise depositional histories and correlations. We report on an extended succession of the Ischigualasto Formation exposed in the Hoyada del Cerro Las Lajas (La Rioja, Argentina), where more than 100 tetrapod fossils were newly collected, augmented by historical finds such as the ornithosuchid Venaticosuchus rusconii and the putative ornithischian Pisanosaurus mertii. Detailed lithostratigraphy combined with high-precision U-Pb geochronology from three intercalated tuffs are used to construct a robust Bayesian age model for the formation, constraining its deposition between 230.2 ± 1.9 Ma and 221.4 ± 1.2 Ma, and its fossil-bearing interval to 229.20 + 0.11/- 0.15-226.85 + 1.45/- 2.01 Ma. The latter is divided into a lower Hyperodapedon and an upper Teyumbaita biozones, based on the ranges of the eponymous rhynchosaurs, allowing biostratigraphic correlations to elsewhere in the Ischigualasto-Villa Unión Basin, as well as to the Paraná Basin in Brazil. The temporally calibrated Ischigualasto biostratigraphy suggests the persistence of rhynchosaur-dominated faunas into the earliest Norian. Our ca. 229 Ma age assignment to Pi. mertii partially fills the ghost lineage between younger ornithischian records and the oldest known saurischians at ca. 233 Ma.",
    url = "https://doi.org/10.1038/s41598-020-67854-1",
    doi = "10.1038/s41598-020-67854-1",
    openalex = "W3045879460",
    references = "doi101016c20090644421, doi101016jgr201801005, doi101016jquascirev200807009, doi101016s0753396900800026, doi101017cbo9780511612381, doi101017s1755691013000431, doi101038nature22037, doi101073pnas1402369111, doi101080027246342013818546, doi101080027246342013820113, doi101080031155182015994114, doi101098rstb19740001, doi101111j109600311988tb00514x, doi101111j10963642200900631x, doi101111j14679876200800623x, doi101126science1198467, doi101144sp37916, doi1012063521, doi1018814epiiugs2013v36i3002, doi1023071005355, doi1023072413376, doi107717peerj1778"
}

La presentación expone las ideas centrales de la clase teórica correspondiente a la asignatura "Espacios Turísticos Americanos", Unidad 8: Región Nuevo Cuyo de la República Argentina, integrada por las provincias de La Rioja, San Juan, Mendoza y San Luis. El nombre de esta región deriva del Tratado del Nuevo Cuyo (firmado en 1988) donde se incorpora la provincia de La Rioja a la región cuyana (originalmente integrada por San Juan, Mendoza y San Luis). Si bien, el tratado respondía a intereses económico-productivos, dado que permitía la inclusión de La Rioja en la promoción de la producción vitivinícola que caracteriza a la región cuyana, existe una cuestión geológica que permite sostener este nuevo agrupamiento jurisdiccional. La historia de la Tierra se expresa a partir de las eras geológicas, durante el Mesozoico, en el período Triásico (entre 230 y 185 millones de años) dominado por dinosaurios y reptiles, surge la Formación Ischigualasto en el Triásico Superior y la Formación Talampaya en el Triásico Superior; en la actualidad se encuentran en el límite entre San Juan y La Rioja, ambas revisten el carácter de Áreas Protegidas (Parque Provincial Ischigualasto y Parque Nacional Talampaya, respectivamente) porque protegen "geoformas" (esculturas talladas por la naturaleza) que se transforman en el rasgo distintivo de la región. A la oferta de geoformas se suma el Parque Nacional Sierras de la Quijadas (San Luis) y sus estribaciones que alcanzan el nordeste de Mendoza, permiten plantear un circuito turístico promocionado por el Ente Cuyo Turismo como la Ruta de los Dinosaurios, donde a partir de la imagen de esta especie extinguida se unen los sitios de contemplación de geoformas, destinos turísticos y centros de pernoctación localizados más próximos a las áreas protegidas. La región presenta una dicotomía territorial, con población concentrada en los oasis fluviales y serranos, en contraposición a grandes vacíos urbanos. El principal acontecimiento programado es la Fiesta Nacional de la Vendimia, realizada cada año en Mendoza durante la primera semana de marzo y el sitio natural más destacado es el cerro Aconcagua (6959 m) pico de mayor altura en la Cordillera de los Andes y América. Se destacan como estaciones de esquí: Las Leñas (único centro invernal integral o de tercera general) y Los Penitentes, ambos en la provincia de Mendoza. Es la región del sol y del buen vino, el olivo junto con el aceite y la producción de aceitunas, frutos disecados, conservas y sus derivados, así como también presenta escenarios propicios para el Turismo de Aventura.

@article{s2dc83fc28e9875d2be885e773b01910d7a765ac53,
    author = "Benseny, Graciela",
    title = "Tips para analizar los espacios turísticos de la Región Nuevo Cuyo",
    year = "2020",
    journal = "NulanFCEyS (Economic and Social National University of Mar del Plata)",
    abstract = {La presentación expone las ideas centrales de la clase teórica correspondiente a la asignatura "Espacios Turísticos Americanos", Unidad 8: Región Nuevo Cuyo de la República Argentina, integrada por las provincias de La Rioja, San Juan, Mendoza y San Luis. El nombre de esta región deriva del Tratado del Nuevo Cuyo (firmado en 1988) donde se incorpora la provincia de La Rioja a la región cuyana (originalmente integrada por San Juan, Mendoza y San Luis). Si bien, el tratado respondía a intereses económico-productivos, dado que permitía la inclusión de La Rioja en la promoción de la producción vitivinícola que caracteriza a la región cuyana, existe una cuestión geológica que permite sostener este nuevo agrupamiento jurisdiccional. La historia de la Tierra se expresa a partir de las eras geológicas, durante el Mesozoico, en el período Triásico (entre 230 y 185 millones de años) dominado por dinosaurios y reptiles, surge la Formación Ischigualasto en el Triásico Superior y la Formación Talampaya en el Triásico Superior; en la actualidad se encuentran en el límite entre San Juan y La Rioja, ambas revisten el carácter de Áreas Protegidas (Parque Provincial Ischigualasto y Parque Nacional Talampaya, respectivamente) porque protegen "geoformas" (esculturas talladas por la naturaleza) que se transforman en el rasgo distintivo de la región. A la oferta de geoformas se suma el Parque Nacional Sierras de la Quijadas (San Luis) y sus estribaciones que alcanzan el nordeste de Mendoza, permiten plantear un circuito turístico promocionado por el Ente Cuyo Turismo como la Ruta de los Dinosaurios, donde a partir de la imagen de esta especie extinguida se unen los sitios de contemplación de geoformas, destinos turísticos y centros de pernoctación localizados más próximos a las áreas protegidas. La región presenta una dicotomía territorial, con población concentrada en los oasis fluviales y serranos, en contraposición a grandes vacíos urbanos. El principal acontecimiento programado es la Fiesta Nacional de la Vendimia, realizada cada año en Mendoza durante la primera semana de marzo y el sitio natural más destacado es el cerro Aconcagua (6959 m) pico de mayor altura en la Cordillera de los Andes y América. Se destacan como estaciones de esquí: Las Leñas (único centro invernal integral o de tercera general) y Los Penitentes, ambos en la provincia de Mendoza. Es la región del sol y del buen vino, el olivo junto con el aceite y la producción de aceitunas, frutos disecados, conservas y sus derivados, así como también presenta escenarios propicios para el Turismo de Aventura.},
    url = "https://www.semanticscholar.org/paper/dc83fc28e9875d2be885e773b01910d7a765ac53",
    is_oa = "true",
    openalex = "W3046401599",
    semanticscholar_id = "dc83fc28e9875d2be885e773b01910d7a765ac53"
}

@inproceedings{androjas2021utilizing,
    author = "Rojas, Alexia and Currie, Brian and Colombi, Carina E.",
    title = "UTILIZING REMOTE GEOLOGIC MAPPING TO ANALYZE STRATIGRAPHIC VARIATION IN THE TRIASSIC ISCHIGUALASTO FORMATION, SAN JUAN PROVINCE, ARGENTINA",
    year = "2021",
    booktitle = "Geological Society of America Abstracts with Programs",
    url = "https://doi.org/10.1130/abs/2021am-367312",
    doi = "10.1130/abs/2021am-367312",
    openalex = "W3208135392"
}

The discovery of theropod shed teeth associated with sauropod remains is relatively common in Cretaceous deposits of Patagonia. However, only a handful of studies have thoroughly explored the phylogenetic affinities of the theropod dental material. Here, we describe and identify twelve theropod shed teeth associated with a partially complete skeleton of a titanosaur sauropod from the Allen Formation (middle Campanian-lower Maastrichtian; Upper Cretaceous) of Paso Crdoba, Ro Negro, Argentina. Using three methods, namely a cladistic analysis performed on a dentition-based data matrix, and a discriminant and cluster analyses conducted on a large dataset of theropod teeth measurements, we identify three dental morphotypes which are confidently referred to abelisaurid theropods. Whether the morphotypes represent different abelisaurid subclades or different positional entities within the jaw of the same abelisaurid species, is unknown. Such an identification, nevertheless, provides additional evidence of abelisaurids feeding on sauropod carcasses. This study highlights the importance of using combined qualitative and quantitative methodologies to identify isolated theropod teeth, especially those that can provide direct information on feeding ecology.

@article{doi104202app008472020,
    author = "Meso, Jorge Gustavo and Hendrickx, Christophe and Baiano, Mattia A. and Canale, Juan I. and Salgado, Leonardo and Díaz‐Martínez, Ignacio",
    title = "ISOLATED THEROPOD TEETH ASSOCIATED WITH A SAUROPOD SKELETON FROM THE ALLEN FORMATION (CAMPANIAN−MAASTRICHTIAN, UPPER CRETACEOUS) OF RÍO NEGRO, PATAGONIA, ARGENTINA.",
    year = "2021",
    journal = "Acta Palaeontologica Polonica",
    abstract = "The discovery of theropod shed teeth associated with sauropod remains is relatively common in Cretaceous deposits of Patagonia. However, only a handful of studies have thoroughly explored the phylogenetic affinities of the theropod dental material. Here, we describe and identify twelve theropod shed teeth associated with a partially complete skeleton of a titanosaur sauropod from the Allen Formation (middle Campanian-lower Maastrichtian; Upper Cretaceous) of Paso Crdoba, Ro Negro, Argentina. Using three methods, namely a cladistic analysis performed on a dentition-based data matrix, and a discriminant and cluster analyses conducted on a large dataset of theropod teeth measurements, we identify three dental morphotypes which are confidently referred to abelisaurid theropods. Whether the morphotypes represent different abelisaurid subclades or different positional entities within the jaw of the same abelisaurid species, is unknown. Such an identification, nevertheless, provides additional evidence of abelisaurids feeding on sauropod carcasses. This study highlights the importance of using combined qualitative and quantitative methodologies to identify isolated theropod teeth, especially those that can provide direct information on feeding ecology.",
    url = "https://doi.org/10.4202/app.00847.2020",
    doi = "10.4202/app.00847.2020",
    openalex = "W3166828028",
    references = "doi101016jcretres2019104312"
}

In this contribution, fossil woods from the Valle de La Luna Member of the Upper Triassic Ischigualasto Formation at Ischigualasto Provincial Park, San Juan Province, Argentina, are described. The specimens are preserved as silica permineralization in tuffs intercalated with carbonaceous mudstone beds interpreted as distal floodplain facies. The fossil woods were assigned to the new species Agathoxylon argentinum since their anatomy differs from the known Mesozoic Gondwanan species of the genus Agathoxylon. The combination of characters present in the new taxon indicates an affiliation with the conifer family Araucariaceae. Signals of fungal-mediated wood decay were observed, comparable to the activity of basidiomycetes. Spherical structures attached to the walls of the tracheids were recognized and are interpreted as holocarpic chytrid fungi. The growth rings were quantitatively analyzed. Low values of percentage diminution, percentage latewood, and Ring Markedness Index, and a mean percentage skew of +11.5, were obtained, suggesting that the new species was an evergreen gymnosperm. The stratigraphic distribution and taxonomic composition of the Ischigualasto Formation fossil-plant-bearing levels were studied. A vegetation change is recorded in the fossil level bearing Agathoxylon argentinum n. sp., marked by the replacement of the corystosperm genera and a diminution of arboreal corystosperms. This floristic change, in addition to other evidence, indicates humid paleoclimatic conditions for the uppermost part of the Valle de La Luna Member of the Ischigualasto Formation.

@article{bodnar2022araucariaceous,
    author = "Bodnar, Josefina and Sagasti, Ana Julia and Correa, Gustavo A. and Miranda, Victoria and Medina, Florencia",
    title = "Araucariaceous fossil woods from the Upper Triassic Ischigualasto Formation (San Juan Province, Argentina): paleofloristic and paleoclimatic implications",
    year = "2022",
    journal = "Journal of Paleontology",
    abstract = "In this contribution, fossil woods from the Valle de La Luna Member of the Upper Triassic Ischigualasto Formation at Ischigualasto Provincial Park, San Juan Province, Argentina, are described. The specimens are preserved as silica permineralization in tuffs intercalated with carbonaceous mudstone beds interpreted as distal floodplain facies. The fossil woods were assigned to the new species Agathoxylon argentinum since their anatomy differs from the known Mesozoic Gondwanan species of the genus Agathoxylon. The combination of characters present in the new taxon indicates an affiliation with the conifer family Araucariaceae. Signals of fungal-mediated wood decay were observed, comparable to the activity of basidiomycetes. Spherical structures attached to the walls of the tracheids were recognized and are interpreted as holocarpic chytrid fungi. The growth rings were quantitatively analyzed. Low values of percentage diminution, percentage latewood, and Ring Markedness Index, and a mean percentage skew of +11.5, were obtained, suggesting that the new species was an evergreen gymnosperm. The stratigraphic distribution and taxonomic composition of the Ischigualasto Formation fossil-plant-bearing levels were studied. A vegetation change is recorded in the fossil level bearing Agathoxylon argentinum n. sp., marked by the replacement of the corystosperm genera and a diminution of arboreal corystosperms. This floristic change, in addition to other evidence, indicates humid paleoclimatic conditions for the uppermost part of the Valle de La Luna Member of the Ischigualasto Formation.",
    url = "https://doi.org/10.1017/jpa.2022.45",
    doi = "10.1017/jpa.2022.45",
    number = "6",
    openalex = "W4286471267",
    pages = "1354-1378",
    volume = "96",
    references = "doi101007bf02862630, doi101007s0022601205147, doi101016jfbr200709001, doi101016jpalaeo200606041, doi1011632294193290000349, doi101306m46497, doi105860choice442115, openalexw1921158499, openalexw361252124, openalexw617829147"
}

Tarjadia ruthae is a quadrupedal terrestrial pseudosuchian from the Middle-early Upper Triassic of the Chañares Formation, La Rioja Province, Argentina. Originally, this species was identified as an indeterminate archosaur and later as a doswelliid archosauriform based on very fragmentary specimens characterized by the ornamentation of the skull roof and osteoderms. Additional specimens (including skulls and postcrania) recovered in the last decade show that Tarjadia is an erpetosuchid, an enigmatic pseudosuchian group composed of six species registered in Middle-Upper Triassic continental units of Tanzania, Germany, Scotland, North America, Brazil, and Argentina. Tarjadia ruthae from Argentina and Parringtonia gracilis from Tanzania are the best preserved and more abundant species. Although the monophyly of Erpetosuchidae is well supported, alternative high-level positions within Archosauria have been suggested, such as sister taxon to Crocodylomorpha, Aetosauria, or Ornithosuchidae. In order to improve the knowledge about the erpetosuchids, we performed a detailed description and paleoneurological reconstruction of the skull of Tarjadia ruthae, based on two articulated partial skulls (CRILAR-Pv 478 and CRILAR-Pv 495) and other fragmentary specimens. We analyzed the stratigraphic and geographic occurrence of historical and new specimens of Tarjadia and provided a new emended diagnosis (the same for the genus as for the species, due to monotypy) along with a comparative description of the cranial endocast. The skull of Tarjadia is robust, with a thick and strongly ornamented skull roof, triangular in dorsal view, with concave lateral margins at mid-length that form an abrupt widened posterior region. The external nares are the smallest openings of the skull. The antorbital fossa is deeply excavated and has a small heart-shaped fenestra with both lobes pointing anteriorly. The supratemporal fenestrae are as large and rounded as the orbits, and the infratemporal fenestrae are L-shaped with an extensive excavation along the jugal, quadratojugal and quadrate. The hemimandibles are low, slightly concave on the dentigerous region and strongly convex on the posterior region, conferring them a S-shaped profile in dorsal view. The external mandibular fenestra is small and elliptic, being twice longer than high. The maxillary dentition is restricted to the anterior to mid region of the rostrum. Since the braincase of both specimens is partially damaged, the dorsal surface of the brain could not be entirely reconstructed. As a result, the endocast is anteroposteriorly elongated and seemingly flat, and the cephalic flexure seems to be lower than expected for a suchian. The labyrinth is twice wider than high, the semicircular canals are remarkably straight, and the anterior canal is longer than the posterior one.

@article{doi101002ar25382,
    author = "Desojo, Julia B. and von Baczko, M. Belén and Ezcurra, Martín D. and Fiorelli, Lucas E. and Martinelli, Agustín G. and Bona, Paula and Trotteyn, M. Jimena and Lacerda, Marcel B.",
    title = "Cranial osteology and paleoneurology of Tarjadia ruthae: An erpetosuchid pseudosuchian from the Triassic Chañares Formation (late Ladinian‐?early Carnian) of Argentina",
    year = "2024",
    journal = "The Anatomical Record",
    abstract = "Tarjadia ruthae is a quadrupedal terrestrial pseudosuchian from the Middle-early Upper Triassic of the Chañares Formation, La Rioja Province, Argentina. Originally, this species was identified as an indeterminate archosaur and later as a doswelliid archosauriform based on very fragmentary specimens characterized by the ornamentation of the skull roof and osteoderms. Additional specimens (including skulls and postcrania) recovered in the last decade show that Tarjadia is an erpetosuchid, an enigmatic pseudosuchian group composed of six species registered in Middle-Upper Triassic continental units of Tanzania, Germany, Scotland, North America, Brazil, and Argentina. Tarjadia ruthae from Argentina and Parringtonia gracilis from Tanzania are the best preserved and more abundant species. Although the monophyly of Erpetosuchidae is well supported, alternative high-level positions within Archosauria have been suggested, such as sister taxon to Crocodylomorpha, Aetosauria, or Ornithosuchidae. In order to improve the knowledge about the erpetosuchids, we performed a detailed description and paleoneurological reconstruction of the skull of Tarjadia ruthae, based on two articulated partial skulls (CRILAR-Pv 478 and CRILAR-Pv 495) and other fragmentary specimens. We analyzed the stratigraphic and geographic occurrence of historical and new specimens of Tarjadia and provided a new emended diagnosis (the same for the genus as for the species, due to monotypy) along with a comparative description of the cranial endocast. The skull of Tarjadia is robust, with a thick and strongly ornamented skull roof, triangular in dorsal view, with concave lateral margins at mid-length that form an abrupt widened posterior region. The external nares are the smallest openings of the skull. The antorbital fossa is deeply excavated and has a small heart-shaped fenestra with both lobes pointing anteriorly. The supratemporal fenestrae are as large and rounded as the orbits, and the infratemporal fenestrae are L-shaped with an extensive excavation along the jugal, quadratojugal and quadrate. The hemimandibles are low, slightly concave on the dentigerous region and strongly convex on the posterior region, conferring them a S-shaped profile in dorsal view. The external mandibular fenestra is small and elliptic, being twice longer than high. The maxillary dentition is restricted to the anterior to mid region of the rostrum. Since the braincase of both specimens is partially damaged, the dorsal surface of the brain could not be entirely reconstructed. As a result, the endocast is anteroposteriorly elongated and seemingly flat, and the cephalic flexure seems to be lower than expected for a suchian. The labyrinth is twice wider than high, the semicircular canals are remarkably straight, and the anterior canal is longer than the posterior one.",
    url = "https://doi.org/10.1002/ar.25382",
    doi = "10.1002/ar.25382",
    openalex = "W4391171414",
    references = "vonbaczko2024paleoneurology"
}

We present the anatomical study of axes of the corystosperm Rhexoxylon piatnitzkyi and the interactions of this plant with wood-boring beetles. We used a CT scanner and thin sections to reconstruct the boring pattern inside the plant axes, as well as the tissues affected by the beetle. The galleries were abundant in the branch of R. piatnitzkyi, including both longitudinal and transverse borings, and less frequent in the trunks. The galleries are bored preferentially in the secondary phloem and in the pith. The position of the galleries as well as the cell and tissue composition of the frass indicates that the borer was mainly a corticophagous insect. The sample also presents evidence of white rot by lignivorous fungi, and fragments of tracheids can be recognised in the frass that fills the galleries, indicating that the borer had some capacity to feed on decayed wood. The anatomical features of the secondary xylem and phloem suggest that the plant deployed defence mechanisms against the fungal decay and/or the boring beetle. This is the first evidence of insect galleries in axes of corystosperms, a dominant group of plants during the Triassic in Gondwana, and the first possible record of cerambycid borings.

@article{doi1010800891296320242354962,
    author = "Sagasti, Ana Julia and Pino, Santiago Hernández Del and Bodnar, Josefina",
    title = "Rhexoxylon piatnitzkyi and its ancient adversaries: deciphering plant-beetle interactions and its palaeoecological significance in the Ischigualasto Formation (Upper Triassic, Argentina)",
    year = "2024",
    journal = "Historical Biology",
    abstract = "We present the anatomical study of axes of the corystosperm Rhexoxylon piatnitzkyi and the interactions of this plant with wood-boring beetles. We used a CT scanner and thin sections to reconstruct the boring pattern inside the plant axes, as well as the tissues affected by the beetle. The galleries were abundant in the branch of R. piatnitzkyi, including both longitudinal and transverse borings, and less frequent in the trunks. The galleries are bored preferentially in the secondary phloem and in the pith. The position of the galleries as well as the cell and tissue composition of the frass indicates that the borer was mainly a corticophagous insect. The sample also presents evidence of white rot by lignivorous fungi, and fragments of tracheids can be recognised in the frass that fills the galleries, indicating that the borer had some capacity to feed on decayed wood. The anatomical features of the secondary xylem and phloem suggest that the plant deployed defence mechanisms against the fungal decay and/or the boring beetle. This is the first evidence of insect galleries in axes of corystosperms, a dominant group of plants during the Triassic in Gondwana, and the first possible record of cerambycid borings.",
    url = "https://doi.org/10.1080/08912963.2024.2354962",
    doi = "10.1080/08912963.2024.2354962",
    openalex = "W4399477035",
    references = "bodnar2022araucariaceous, doi1010079783642573026, doi101007s1143400901694, doi101016jfbr200709001, doi101016jmri201205001, doi101111brv12158, doi101111j146981371996tb01842x, doi101111j14698137200501436x, doi101146annureves17110186000435, doi101146annurevpy29090191002121, doi105710amgh161120223520, doi105860choice404600"
}

Non‐crocodylomorph loricatans, traditionally known as “rauisuchians,” are considered as the top predators of the Triassic continental faunas that reigned before the emergence of the well‐known theropod dinosaurs. In particular, Saurosuchus galilei is a large quadrupedal prestosuchid loricatan found in the Ischigualasto Formation from northwestern Argentina. Here, we reevaluated the braincase of S. galilei and present the first paleoneurological study based on the partial natural casts of the holotype and the digital cranial endocast of the referred specimen PVSJ 32. The braincase of S. galilei was here reinterpreted, identifying the sutures of the supraoccipital, otoccipital, basioccipital, parabasisphenoid, prootic, and laterosphenoid. A unique feature identified in the braincase of S. galilei is the presence of deep paracondylar recesses associated with pharyngotympanic pneumaticity, which has not been identified in any other “rauisuchians” so far. Most of the structures of the encephalon were recognized in the cranial endocast and natural casts including cranial nerves V–XII, olfactory bulbs, main blood vessels and sinuses, and inner ear. These structures allowed us to quantify some of its sensorial capacities and recognize that S. galilei had an enhanced olfactory acuity, with coefficients higher than those expected for its body size, a condition previously observed in living crocodilians and tyrannosaurid dinosaurs. An improved sense of smell might have allowed Saurosuchus to track its prey from long distances and compensate for the poorer development of its other senses like vision and balance.

@article{vonbaczko2024paleoneurology,
    author = "von Baczko, M. Belén and Cardillo, Ariel F. and Ulloa‐Guaiquin, Karen and Desojo, Julia B. and Paulina‐Carabajal, Ariana",
    title = "Paleoneurology and neuroanatomical notes on the South American “rauisuchian” Saurosuchus galilei from the Ischigualasto formation, San Juan, Argentina",
    year = "2024",
    journal = "The Anatomical Record",
    abstract = "Non‐crocodylomorph loricatans, traditionally known as “rauisuchians,” are considered as the top predators of the Triassic continental faunas that reigned before the emergence of the well‐known theropod dinosaurs. In particular, Saurosuchus galilei is a large quadrupedal prestosuchid loricatan found in the Ischigualasto Formation from northwestern Argentina. Here, we reevaluated the braincase of S. galilei and present the first paleoneurological study based on the partial natural casts of the holotype and the digital cranial endocast of the referred specimen PVSJ 32. The braincase of S. galilei was here reinterpreted, identifying the sutures of the supraoccipital, otoccipital, basioccipital, parabasisphenoid, prootic, and laterosphenoid. A unique feature identified in the braincase of S. galilei is the presence of deep paracondylar recesses associated with pharyngotympanic pneumaticity, which has not been identified in any other “rauisuchians” so far. Most of the structures of the encephalon were recognized in the cranial endocast and natural casts including cranial nerves V–XII, olfactory bulbs, main blood vessels and sinuses, and inner ear. These structures allowed us to quantify some of its sensorial capacities and recognize that S. galilei had an enhanced olfactory acuity, with coefficients higher than those expected for its body size, a condition previously observed in living crocodilians and tyrannosaurid dinosaurs. An improved sense of smell might have allowed Saurosuchus to track its prey from long distances and compensate for the poorer development of its other senses like vision and balance.",
    url = "https://doi.org/10.1002/ar.25362",
    doi = "10.1002/ar.25362",
    number = "4",
    openalex = "W4390114134",
    pages = "1239-1253",
    volume = "307",
    references = "doi101002ar20983, doi10100797830311398338, doi10100797844317693306, doi101038nature02048, doi101073pnas0704250104, doi101126science2865440711, doi1012063521, doi1016710272463420072732caomct20co2, doi1023071005355, doi1023071441916, doi105962bhltitle61419"
}

La presente contribución corresponde al trabajo de tesis titulado “La paleoflora triásica del Grupo Sorocayense en la región de Hilario, cuenca de Barreal-Calingasta, Provincia de San Juan”. Esta contribución tiene como propósito principal el entendimiento de los aspectos paleoambientales y evolutivos de la flora triásica del noroeste de la Argentina. Durante los 12 viajes de campo realizados entre los años 2015 y 2019 al depocentro Agua de los Pajaritos, se reconoció la presencia de cuatro unidades litoestratigráficas (Agua de los Pajaritos, Monina, Hilario y El Alcázar). Se relevaron perfiles sedimentológicos en las quebradas de la Zorra, Colón, del Cerro El Alcázar y Arroyo Agua de los Pajaritos. En esta última se reconocieron estratos fosilíferos portadores de impresiones-compresiones, carbonizaciones y permineralizaciones de vegetales, mencionados por autores previos, como así también nuevos estratos fosilíferos. En total se obtuvieron 170 ejemplares de impresiones-compresiones de tallos, hojas y estructuras reproductivas y 50 ejemplares de troncos permineralizados. Los estudios sedimentológicos, en base al reconocimiento de litofacies, facies y asociaciones de facies, permitió el reconocimiento de los paleoambiente de sedimentación de las formaciones del depocentro Agua de los Pajaritos. La Formación Agua de Los Pajaritos fue depositada por un sistema fluvial entrelazado gravoso y por un sistema meandriforme areno-gravoso, en su parte superior. Por su parte, se confirmó la validez de la Formación Monina e infirió que correspondería a sistemas depositacionales deltaicos en la base de la unidad, meandriforme somero en la pate media y lacustre somero en la parte superior. La Formación Hilario también fue convalidada por el análisis sedimentológico. Se interpretó como constituida por una asociación de facies de plataforma deltaica en un lago poco profundo, con ocasionales caídas de ceniza volcánica y depósitos de canales amalgamados coronando la unidad. Por último, la Formación El Alcázar fue dividida en tres miembros, de base a techo, son: “Miembro Tobas Blancas” correspondiente a depósitos piroclásticos de flujo y caída, “Miembro Tobas Varicolores” interpretados como depósitos de llanura volcaniclástica perturbado por períodos de caída de lluvias de ceniza, y el “Miembro Tobas Rosadas” interpretado como un sistema anastomosado. En contacto con el techo de la Formación El Alcázar, se definió una nueva asociación de facies correspondiente a canales gravo-arenosos, que presentan superficies erosivas y de reactivación. Estos fueron interpretados como generados a partir de un sistema entrelazado gravoso con depósitos de flujo gravitatorios. Finalmente, se realizó un modelo de evolución paleoambiental de la cubeta, y se lo comparó con los modelos ya publicados para los depocentros Rincón Blanco y Barreal. El estudio sistemático de la paleoflora realizado permitió reconocer dos estratos fosilíferos en la Formación Monina y doce en la Formación El Alcázar. Además, se correlacionaron los estratos plantíferos relevados por trabajos de autores previos. Se identificaron los 32 taxones en las formaciones estudiadas (siete en Monina y 25 en El Alcázar): Lepacyclotes sp., Equisetites fertilis, Neocalamites carrerei, Nododendron sp., Cladophlebis mesozoica, Pecopteris sp., Thaumatopteris barrealensis, Dicroidium argenteum, Dicroidium sp., Johnstonia coriacea, Zuberia feistmanteli, Zuberia zuberi, Zuberia sp., Umkomasia cf. macleanii, Rhexoxylon cortaderitaense, Tranquiloxyon sp. nov., Pachydermophyllum pinnatum, Scytophyllum bonettiae, Scytophyllum sp., Dejerseya cf. lunensis, Matatiella cf roseta, Kurtziana cacheutensis, Sphenobaiera argentinae, Sphenobaiera cf. schenkii, Sphenobaiera stormbergensis, Heidiphyllum minutifolium, Yabeiella brackebuschiana, Yabeiella mareyesiaca, Rissikianthus sp., Cordaicarpus sp., Acevedoa cf. rastroensis y Protocircoporoxylon sp. Se registró por primera vez la presencia de fósiles vegetales descriptos para la Formación Monina. El hallazgo y descripción del género Matatiela, constituye el primer registro de este taxón en Argentina. Los géneros Acevedoa y Protocircoporoxylon, amplían la distribución de estos taxones a la cuenca Cuyana, ya que se habían descripto para unidades de la cuenca Ischigualasto-Villa Unión y el depocentro Paso Flores, respectivamente. Para la Formación El Alcázar se citan por primera vez las especies Equisetites fertilis, Thaumatopteris barrealensis, Dicroidium argenteum, Umkomasia cf. macleanii, Pachydermophyllum pinnatum, Scytophyllum bonettiae, Sphenobaiera cf. schenkii y Heidiphyllum minutifolium; y los géneros Zuberia y Nododendron. En relación al análisis tafonómico se describieron cuatro estilos preservacionales en la Formación Monina y nueve estilos preservacionales para la Formación El Alcázar. Tomando como punto de partida los estilos preservacionales de ambas formaciones, se definieron las tafofacies correspondientes a cada unidad litoestratigráfica. En relación a la distribución de tafofacies en la Formación Monina, se observó que, la cantidad y abundancia de fósiles se da en los primeros metros con la presencia de dos tafofacies. En los niveles superiores solo se preservó materia orgánica en forma de bitumen. En la Formación El Alcázar, se pudieron reconocer ocho tafofacies, distribuidas de manera desigual en cada una de las asociaciones de facies. En la base de la formación, “Miembro Tobas Blancas”, se encontró una sola tafofacies, distribuida de manera uniforme, aunque de pocos metros de espesor. En la parte media, o Miembro Tobas Varicolores”, se comprobó la presencia de la mayor cantidad de tafofacies (cinco). Esta sección de la Formación El Alcázar, es la que presenta mayor diversidad y abundancia fosilífera. En el “Miembro Tobas Rosadas”, se describieron cuatro tafofacies. Se pudo comprobar mediante el estudio y la descripción de las tafofacies que las condiciones geoquímicas variaron de una asociación de facies a otra, de reductoras a más oxidantes. Haciendo hincapié en las asociaciones de facies 9 y 10, se observó un cambio climático en donde se establece un clima subtropical subhúmedo a semiárido de régimen estacional en la AF9, a un régimen subtropical estacional semiárido visto en la AF10. El análisis paleoecológico de las tafocenosis permitió definir doce paleocomunidades. Las presentes en la Formación Monina fueron definidas como bosques caducifolios de clima subtropical estacional con un sotobosque dominado por peltaspermales y bosques de coníferas monotípicos. La Formación El Alcázar presenta dos grandes tipos de paleocomunidades: aquellos con una gran cantidad de elementos arbóreos representados en su mayoría por Ginkgoales, Umkomasiales y Gnetales, asociados a Osmundales, Gleicheniales, Maratiales, Peltaspermales y Equisetales como elementos del sotobosque, y una abundancia en cuanto a la presencia de matorrales de esfenofitas. Se realizó la correlación litoestratigráfica de las formaciones del depocentro Agua de los Pajaritos, con las formaciones de los depocentros Barreal y Rincón Blanco, teniendo en cuenta, las litologías, los ambientes depositacionales y las relaciones entre los distintos cuerpos de roca. Finalmente, para el análisis bioestratigráfico, se analizó el biocrón de los taxones hallados en las formaciones Monina y El Alcázar, ubicándolas en el intervalo Anisiano-Retiano. Además, se comparó la flora de la Formación El Alcázar, con otras floras de formaciones triásicas de la Argentina por medio de un análisis de agrupamiento. Todas estas evidencias permitieron considerar a la Formación El Alcázar de edad mesotriásica tardía.

@misc{doi103553710915143720,
    author = "Drovandi, Juan",
    title = "La paleoflora triásica del Grupo Sorocayense en la Región de Hilario, Cuenca de Barreal-Calingasta, provincia de San Juan",
    year = "None",
    abstract = "La presente contribución corresponde al trabajo de tesis titulado “La paleoflora triásica del Grupo Sorocayense en la región de Hilario, cuenca de Barreal-Calingasta, Provincia de San Juan”. Esta contribución tiene como propósito principal el entendimiento de los aspectos paleoambientales y evolutivos de la flora triásica del noroeste de la Argentina. Durante los 12 viajes de campo realizados entre los años 2015 y 2019 al depocentro Agua de los Pajaritos, se reconoció la presencia de cuatro unidades litoestratigráficas (Agua de los Pajaritos, Monina, Hilario y El Alcázar). Se relevaron perfiles sedimentológicos en las quebradas de la Zorra, Colón, del Cerro El Alcázar y Arroyo Agua de los Pajaritos. En esta última se reconocieron estratos fosilíferos portadores de impresiones-compresiones, carbonizaciones y permineralizaciones de vegetales, mencionados por autores previos, como así también nuevos estratos fosilíferos. En total se obtuvieron 170 ejemplares de impresiones-compresiones de tallos, hojas y estructuras reproductivas y 50 ejemplares de troncos permineralizados. Los estudios sedimentológicos, en base al reconocimiento de litofacies, facies y asociaciones de facies, permitió el reconocimiento de los paleoambiente de sedimentación de las formaciones del depocentro Agua de los Pajaritos. La Formación Agua de Los Pajaritos fue depositada por un sistema fluvial entrelazado gravoso y por un sistema meandriforme areno-gravoso, en su parte superior. Por su parte, se confirmó la validez de la Formación Monina e infirió que correspondería a sistemas depositacionales deltaicos en la base de la unidad, meandriforme somero en la pate media y lacustre somero en la parte superior. La Formación Hilario también fue convalidada por el análisis sedimentológico. Se interpretó como constituida por una asociación de facies de plataforma deltaica en un lago poco profundo, con ocasionales caídas de ceniza volcánica y depósitos de canales amalgamados coronando la unidad. Por último, la Formación El Alcázar fue dividida en tres miembros, de base a techo, son: “Miembro Tobas Blancas” correspondiente a depósitos piroclásticos de flujo y caída, “Miembro Tobas Varicolores” interpretados como depósitos de llanura volcaniclástica perturbado por períodos de caída de lluvias de ceniza, y el “Miembro Tobas Rosadas” interpretado como un sistema anastomosado. En contacto con el techo de la Formación El Alcázar, se definió una nueva asociación de facies correspondiente a canales gravo-arenosos, que presentan superficies erosivas y de reactivación. Estos fueron interpretados como generados a partir de un sistema entrelazado gravoso con depósitos de flujo gravitatorios. Finalmente, se realizó un modelo de evolución paleoambiental de la cubeta, y se lo comparó con los modelos ya publicados para los depocentros Rincón Blanco y Barreal. El estudio sistemático de la paleoflora realizado permitió reconocer dos estratos fosilíferos en la Formación Monina y doce en la Formación El Alcázar. Además, se correlacionaron los estratos plantíferos relevados por trabajos de autores previos. Se identificaron los 32 taxones en las formaciones estudiadas (siete en Monina y 25 en El Alcázar): Lepacyclotes sp., Equisetites fertilis, Neocalamites carrerei, Nododendron sp., Cladophlebis mesozoica, Pecopteris sp., Thaumatopteris barrealensis, Dicroidium argenteum, Dicroidium sp., Johnstonia coriacea, Zuberia feistmanteli, Zuberia zuberi, Zuberia sp., Umkomasia cf. macleanii, Rhexoxylon cortaderitaense, Tranquiloxyon sp. nov., Pachydermophyllum pinnatum, Scytophyllum bonettiae, Scytophyllum sp., Dejerseya cf. lunensis, Matatiella cf roseta, Kurtziana cacheutensis, Sphenobaiera argentinae, Sphenobaiera cf. schenkii, Sphenobaiera stormbergensis, Heidiphyllum minutifolium, Yabeiella brackebuschiana, Yabeiella mareyesiaca, Rissikianthus sp., Cordaicarpus sp., Acevedoa cf. rastroensis y Protocircoporoxylon sp. Se registró por primera vez la presencia de fósiles vegetales descriptos para la Formación Monina. El hallazgo y descripción del género Matatiela, constituye el primer registro de este taxón en Argentina. Los géneros Acevedoa y Protocircoporoxylon, amplían la distribución de estos taxones a la cuenca Cuyana, ya que se habían descripto para unidades de la cuenca Ischigualasto-Villa Unión y el depocentro Paso Flores, respectivamente. Para la Formación El Alcázar se citan por primera vez las especies Equisetites fertilis, Thaumatopteris barrealensis, Dicroidium argenteum, Umkomasia cf. macleanii, Pachydermophyllum pinnatum, Scytophyllum bonettiae, Sphenobaiera cf. schenkii y Heidiphyllum minutifolium; y los géneros Zuberia y Nododendron. En relación al análisis tafonómico se describieron cuatro estilos preservacionales en la Formación Monina y nueve estilos preservacionales para la Formación El Alcázar. Tomando como punto de partida los estilos preservacionales de ambas formaciones, se definieron las tafofacies correspondientes a cada unidad litoestratigráfica. En relación a la distribución de tafofacies en la Formación Monina, se observó que, la cantidad y abundancia de fósiles se da en los primeros metros con la presencia de dos tafofacies. En los niveles superiores solo se preservó materia orgánica en forma de bitumen. En la Formación El Alcázar, se pudieron reconocer ocho tafofacies, distribuidas de manera desigual en cada una de las asociaciones de facies. En la base de la formación, “Miembro Tobas Blancas”, se encontró una sola tafofacies, distribuida de manera uniforme, aunque de pocos metros de espesor. En la parte media, o Miembro Tobas Varicolores”, se comprobó la presencia de la mayor cantidad de tafofacies (cinco). Esta sección de la Formación El Alcázar, es la que presenta mayor diversidad y abundancia fosilífera. En el “Miembro Tobas Rosadas”, se describieron cuatro tafofacies. Se pudo comprobar mediante el estudio y la descripción de las tafofacies que las condiciones geoquímicas variaron de una asociación de facies a otra, de reductoras a más oxidantes. Haciendo hincapié en las asociaciones de facies 9 y 10, se observó un cambio climático en donde se establece un clima subtropical subhúmedo a semiárido de régimen estacional en la AF9, a un régimen subtropical estacional semiárido visto en la AF10. El análisis paleoecológico de las tafocenosis permitió definir doce paleocomunidades. Las presentes en la Formación Monina fueron definidas como bosques caducifolios de clima subtropical estacional con un sotobosque dominado por peltaspermales y bosques de coníferas monotípicos. La Formación El Alcázar presenta dos grandes tipos de paleocomunidades: aquellos con una gran cantidad de elementos arbóreos representados en su mayoría por Ginkgoales, Umkomasiales y Gnetales, asociados a Osmundales, Gleicheniales, Maratiales, Peltaspermales y Equisetales como elementos del sotobosque, y una abundancia en cuanto a la presencia de matorrales de esfenofitas. Se realizó la correlación litoestratigráfica de las formaciones del depocentro Agua de los Pajaritos, con las formaciones de los depocentros Barreal y Rincón Blanco, teniendo en cuenta, las litologías, los ambientes depositacionales y las relaciones entre los distintos cuerpos de roca. Finalmente, para el análisis bioestratigráfico, se analizó el biocrón de los taxones hallados en las formaciones Monina y El Alcázar, ubicándolas en el intervalo Anisiano-Retiano. Además, se comparó la flora de la Formación El Alcázar, con otras floras de formaciones triásicas de la Argentina por medio de un análisis de agrupamiento. Todas estas evidencias permitieron considerar a la Formación El Alcázar de edad mesotriásica tardía.",
    url = "http://sedici.unlp.edu.ar/bitstream/handle/10915/143720/Documento\_completo.pdf?sequence=1",
    doi = "10.35537/10915/143720",
    is_oa = "true",
    semanticscholar_citation_count = "2",
    semanticscholar_id = "d46b6e21e2d5982fd673a766a5434722ca90ce5e"
}