@article{bone1958the1,
    author = "Bone, Q",
    title = "The central nervous system in larval acraniates",
    year = "1958",
    journal = "Quarterly Journal of Microscopical Science, v. 100, p. 509-527",
    note = "talkorigins\_source = {true}; raw\_reference = {Bone, Q., 1958, The central nervous system in larval acraniates: Quarterly Journal of Microscopical Science, v. 100, p. 509-527.}"
}

@article{bone1959the,
    author = "Bone, Quentin",
    title = "The Central Nervous System in Larval Acraniates",
    year = "1959",
    journal = "Journal of Cell Science",
    abstract = "This paper describes a part of the organization of the spinal cord of the larva of the Acrania, dealing chiefly with those tracts and cell groups that are probably concerned. with the control of the swimming pattern. These observations serve as a basis for the comparison of the organization of the cord of the larva with that of the adult, and with that known for the larvae of the Agnatha and higher vertebrates. Other observations are concerned with the arrangement of the peripheral nervous system, which differs in some respects from that of the adult. The first section deals with the arrangement of the fibre tracts in the cord, and of the cell-bodies which give rise to these fibres. The form and connexions of the giant cells are then described; it is shown that these cells are equivalent to the Rohon-Beard sensory cells of vertebrate embryos. They send peripheral processes out through dorsal root nerves, but they differ from the vertebrate sensory neurones in their greatly enlarged dendrite field and the longitudinal axon in the cord. Thirdly, the innervation of the gill musculature is described. A ventro-lateral asymmetrical nerve is found, formed by the junction of fibres from the right anterior dorsal root nerves. Lastly, the arrangement of the whole system is discussed in relation to the systems found in the larval stages of other primitive chordates.",
    url = "https://doi.org/10.1242/jcs.s3-100.52.509",
    doi = "10.1242/jcs.s3-100.52.509",
    number = "52",
    openalex = "W2219906851",
    pages = "509-527",
    volume = "S3-100",
    references = "doi101002cne900240205, doi101021ed033p3572, doi1023071535762"
}

@article{doi101242jcss310052509,
    author = "Bone, Q.",
    title = "The Central Nervous System in Larval Acraniates",
    year = "1959",
    journal = "Journal of Cell Science",
    abstract = "ABSTRACT This paper describes a part of the organization of the spinal cord of the larva of the Acrania, dealing chiefly with those tracts and cell groups that are probably concerned. with the control of the swimming pattern. These observations serve as a basis for the comparison of the organization of the cord of the larva with that of the adult, and with that known for the larvae of the Agnatha and higher vertebrates. Other observations are concerned with the arrangement of the peripheral nervous system, which differs in some respects from that of the adult. The first section deals with the arrangement of the fibre tracts in the cord, and of the cell-bodies which give rise to these fibres. The form and connexions of the giant cells are then described; it is shown that these cells are equivalent to the Rohon-Beard sensory cells of vertebrate embryos. They send peripheral processes out through dorsal root nerves, but they differ from the vertebrate sensory neurones in their greatly enlarged dendrite field and the longitudinal axon in the cord. Thirdly, the innervation of the gill musculature is described. A ventro-lateral asymmetrical nerve is found, formed by the junction of fibres from the right anterior dorsal root nerves. Lastly, the arrangement of the whole system is discussed in relation to the systems found in the larval stages of other primitive chordates.",
    url = "https://doi.org/10.1242/jcs.s3-100.52.509",
    doi = "10.1242/jcs.s3-100.52.509",
    openalex = "W2219906851",
    references = "doi101002cne900240205, doi101021ed033p3572, doi1023071535762"
}

@incollection{parker1962subphylum,
    author = "Parker, T. Jeffery and Haswell, William A.",
    title = "Sub-Phylum Acrania (Cephalochordata)",
    year = "1962",
    booktitle = "Textbook of Zoology Vertebrates",
    url = "https://doi.org/10.1007/978-1-349-00198-9\_4",
    doi = "10.1007/978-1-349-00198-9\_4",
    openalex = "W2408873747",
    pages = "47-68"
}

@incollection{wickstead1975chordata,
    author = "Wickstead, John H.",
    title = "CHORDATA: ACRANIA (CEPHALOCHORDATA)",
    year = "1975",
    booktitle = "Reproduction of Marine Invertebrates",
    url = "https://doi.org/10.1016/b978-0-12-282502-6.50014-5",
    doi = "10.1016/b978-0-12-282502-6.50014-5",
    openalex = "W2897933019",
    pages = "283-319",
    references = "doi101002jmor1050540103, doi101016b9780122825019500065, doi101017s0025315400000102, doi101038150474a0, doi1010381901061d0, doi101093aibsbulletin6323c, doi101111j109636421910tb00516x, doi101242jcss262246243, doi101242jcss27228551, openalexw2973821230, openalexw301193904, openalexw574596740"
}

@incollection{wickstead1975chordata2,
    author = "Wickstead, J. H",
    editor = "Giese, A. C. and Pearse, J. S.",
    title = "Chordata: Acrania (Cephalochordata)",
    year = "1975",
    booktitle = "Reproduction of Marine Invertebrates II, Entoprocts and Lesser Coelomates",
    publisher = "New York, Academic Press, p. 283-319",
    note = "talkorigins\_source = {true}; raw\_reference = {Wickstead, J. H., 1975, Chordata: Acrania (Cephalochordata), in Giese, A. C., and Pearse, J. S., eds., Reproduction of Marine Invertebrates II, Entoprocts and Lesser Coelomates: New York, Academic Press, p. 283-319.}"
}

@article{doi1023071541578,
    author = "Holland, Nicholas D. and Holland, Linda Z.",
    title = "Fine Structural Study of the Cortical Reaction and Formation of the Egg Coats in a Lancelet (= Amphioxus), Branchiostoma floridae (Phylum Chordata: Subphylum Cephalochordata = Acrania)",
    year = "1989",
    journal = "Biological Bulletin",
    abstract = "A method for artificial fertilization of lancelet eggs is described, and the egg coats are studied for the first time by transmission electron microscopy. Large, ovarian oocytes and spawned, unfertilized eggs (which are about 140 µm in diameter) are surrounded by a coarsely granular vitelline layer about 1 µm thick and a jelly layer a few micrometers thick. The egg cortex is crowded with a monolayer of cortical granules, each with an average diameter of approximately 3.5 µm. About 20 to 30 s after insemination, a cortical reaction occurs almost simultaneously over the entire egg surface. The cortical granules undergo exocytosis, and part of their content evidently forms a dense layer 30 nm thick against the inside of the vitelline layer: both layers together constitute the fertilization envelope, which begins elevating from the egg surface. By 80 s after insemination, the jelly layer has disappeared, and beneath the fertilization envelope the bulk of the ejected cortical granule material has become organized into a hyaline layer with a finely fibrogranular consistency. By 20 min after insemination, the perivitelline space between the fertilization envelope and the egg surface has attained its maximum width of roughly 150 µm, and both the hyaline layer and the vitelline layer component of the fertilization envelope are much attenuated and remain so until hatching about 9 h after insemination. Egg coats are compared among major deuterostome groups, and the results imply that the ancestral chordate may have been an unspecialized appendicularian.",
    url = "https://doi.org/10.2307/1541578",
    doi = "10.2307/1541578",
    openalex = "W2095689929",
    references = "doi101002jmor1050540103, doi10100797814615681485, doi101083jcb1072731, doi101111j146363951981tb00618x, doi101111j146363951988tb00906x, doi101242jcss27228551, doi1023071443999, doi105962bhltitle55924, openalexw564391913, openalexw654005152"
}

@article{holland1989the,
    author = "Holland, Nicholas D. and Holland, Linda Z.",
    title = "The Fine Structure of the Testis of a Lancelet (=Amphioxus), Branchiostoma floridae (Phylum Chordata: Subphylum Cephalochordata= Acrania)",
    year = "1989",
    journal = "Acta Zoologica",
    abstract = "The germinal and non‐germinal cells of the ripe lancelet testis are described by transmission electron microscopy. The visceral peritoneum of the testis is composed of myoepithelial cells, and the haemal layer consists of regions of narrow sinuses and conspicuously thicker blood vessels filled with blood plasma and bounded by basal laminae. Within the germinal epithelium and the testicular lumen, the non‐germinal cells, which are not abundant, contain conspicuous lysosomes and mitochondria with tubular cristae, indicating that they may be involved in steroid synthesis. In the ripe testis, the non‐germinal cells do not appear to be organized into a blood‐testis barrier. Ail types of spermatogenic cells may be flagellated and are joined in small groups by intercellular bridges. During differentiation of the spermatids, the Golgi complex is associated with formation of the acrosomal vesicle near the posterior pole of the cell. A remarkable feature is the dual origin of the subacrosomal material: one component originates at the posterior end of the spermatid, and the other at the anterior end. Subsequently, the two components merge into one after the acrosomal vesicle has migrated to its definitive anterior position in the mature spermatozoon.",
    url = "https://doi.org/10.1111/j.1463-6395.1989.tb00934.x",
    doi = "10.1111/j.1463-6395.1989.tb00934.x",
    number = "4",
    openalex = "W2071969053",
    pages = "211-219",
    volume = "70",
    references = "doi101007bf00310102, doi1010160378432078900155, doi101016b9780122825026500121, doi101111j146363951979tb00594x, doi101111j146363951988tb00906x, doi101111j146364091979tb00640x, openalexw1506527793, openalexw605514449, openalexw654005152, wickstead1975chordata"
}

@article{doi101098rstb19940059,
    author = "Lacalli, Thurston C. and Holland, Nicholas D. and West, J. E.",
    title = "Landmarks in the anterior central nervous system of amphioxus larvae",
    year = "1994",
    journal = "Philosophical Transactions of the Royal Society B Biological Sciences",
    abstract = "Abstract The anterior end of the dorsal nerve cord of amphioxus is described at the 3-4 gill slit stage based on serial transmission electron microscopy and three-dimensional reconstruction, with special attention to structures that are potential landmarks for comparing amphioxus with other chordates. The larval nerve cord is divisible, at approximately the level of the first somite, into a short anterior region, the cerebral vesicle (c.v.), and an extended posterior region that is thought to include homologues of the vertebrate hindbrain and spinal cord. The c.v., in turn, has an anterior part with a tubular neural canal and a posterior part with a keyhole-shaped neural canal similar to that found in the rest of the cord. The junction between these two parts of the c.v. is marked by a cluster of infundibular cells. The anterior c.v., whose cells have cilia that point anteriorly, includes (i) a structure we call the frontal eye, consisting of a pigment spot and transverse rows of putative receptor and nerve cells, and (ii) several small ventral commissures bridging the major nerve tracts that run ventrolaterally along either side of the nerve cord. The posterior c.v., in contrast, contains cells whose cilia point posteriorly, and includes (i) the beginnings of the floorplate, which continues posteriorly through the rest of the nerve cord, (ii) the dorsal lamellar body, made up of cells with cilia that expand into flattened lamellae, and (iii) a large ventral commissure that incorporates fibres arising from cells of the lamellar body. Where probable homologues of c.v. structures can be identified in vertebrate brain, they are found in the diencephalon, which suggests the c.v. and the vertebrate diencephalon are, to a degree, homologous.",
    url = "https://doi.org/10.1098/rstb.1994.0059",
    doi = "10.1098/rstb.1994.0059",
    openalex = "W2034206853",
    references = "bone1959the, doi101002cne901150105, doi101007bf00348527, doi101007bf02028391, doi101016s0022532062800070, doi101111j1440169x198600569x, doi101111j146363951987tb00892x, doi101111j1469185x1989tb00471x, doi101152jn19814651018, doi101242dev1081121, doi101242dev1163653, doi101242jcss310052509, doi101523jneurosci1202004671992, doi101523jneurosci1301002851993, doi1023071541578, doi1023071541854, ruiz1991the"
}

@misc{crossref2005cephalochordata,
    title = "Cephalochordata (Chordata)",
    year = "2005",
    booktitle = "Van Nostrand's Scientific Encyclopedia",
    url = "https://doi.org/10.1002/0471743984.vse1596",
    doi = "10.1002/0471743984.vse1596",
    openalex = "W4245623911"
}

@article{doi10118620419139427,
    author = "Holland, Linda Z. and Carvalho, João E. and Escrivá, Héctor and Laudet, Vincent and Schubert, Michael and Shimeld, Sebastian M. and Yu, Jr‐Kai",
    title = "Evolution of bilaterian central nervous systems: a single origin?",
    year = "2013",
    journal = "EvoDevo",
    abstract = "The question of whether the ancestral bilaterian had a central nervous system (CNS) or a diffuse ectodermal nervous system has been hotly debated. Considerable evidence supports the theory that a CNS evolved just once. However, an alternative view proposes that the chordate CNS evolved from the ectodermal nerve net of a hemichordate-like ancestral deuterostome, implying independent evolution of the CNS in chordates and protostomes. To specify morphological divisions along the anterior/posterior axis, this ancestor used gene networks homologous to those patterning three organizing centers in the vertebrate brain: the anterior neural ridge, the zona limitans intrathalamica and the isthmic organizer, and subsequent evolution of the vertebrate brain involved elaboration of these ancestral signaling centers; however, all or part of these signaling centers were lost from the CNS of invertebrate chordates. The present review analyzes the evidence for and against these theories. The bulk of the evidence indicates that a CNS evolved just once - in the ancestral bilaterian. Importantly, in both protostomes and deuterostomes, the CNS represents a portion of a generally neurogenic ectoderm that is internalized and receives and integrates inputs from sensory cells in the remainder of the ectoderm. The expression patterns of genes involved in medio/lateral (dorso/ventral) patterning of the CNS are similar in protostomes and chordates; however, these genes are not similarly expressed in the ectoderm outside the CNS. Thus, their expression is a better criterion for CNS homologs than the expression of anterior/posterior patterning genes, many of which (for example, Hox genes) are similarly expressed both in the CNS and in the remainder of the ectoderm in many bilaterians. The evidence leaves hemichordates in an ambiguous position - either CNS centralization was lost to some extent at the base of the hemichordates, or even earlier, at the base of the hemichordates + echinoderms, or one of the two hemichordate nerve cords is homologous to the CNS of protostomes and chordates. In any event, the presence of part of the genetic machinery for the anterior neural ridge, the zona limitans intrathalamica and the isthmic organizer in invertebrate chordates together with similar morphology indicates that these organizers were present, at least in part, at the base of the chordates and were probably elaborated upon in the vertebrate lineage.",
    url = "https://doi.org/10.1186/2041-9139-4-27",
    doi = "10.1186/2041-9139-4-27",
    openalex = "W2131278302",
    references = "doi101002jmor10533, doi101002jmor10868, doi101007s004270050225, doi101016jcub200905063, doi101016jgde200506004, doi101016jydbio201005016, doi101111j146363951995tb00986x, doi101111j146979981978tb03931x, doi101242dev066712, doi101242dev12661295, openalexw600124373"
}

@incollection{lacalli2015acrania,
    author = "Lacalli, Thurston and Stach, Thomas",
    title = "Acrania (Cephalochordata)",
    year = "2015",
    booktitle = "Structure and Evolution of Invertebrate Nervous Systems",
    abstract = "This chapter provides an overview and update of the 2005 review of CNS organization in the lancelet (amphioxus) by Wicht and Lacalli (Can. J. Zool. 83: 122–150). While interesting in its own right, amphioxus has a special place in comparative studies as the best available model for ancestral chordates, having replaced tunicates in this role, and there is an increasing body of data on the molecular mechanisms that act to pattern the CNS for comparison with related taxa. Our knowledge of circuitry, cell types, and transmitters in amphioxus is best for the larval stage, where EM and neurochemical maps of the anterior CNS are available. In contrast, there are still large gaps in our understanding of the adult CNS, even in terms of the basic functions that various parts of the system and its constituent cell types perform. The anterior nerve cord is specialized and brain-like, both in terms of molecular signatures and circuitry. Amphioxus has an assortment of receptor cell types, including four kinds of photoreceptors and numerous peripheral receptor cells, and an extensive system of peripheral plexuses whose functions are poorly understood. An anterior secretory structure, the preoral pit, has in the past been considered a possible homologue of the anterior pituitary, but this remains problematic, not least because amphioxus is now known to lack all but one of the hormones produced by the vertebrate pituitary.",
    url = "https://doi.org/10.1093/acprof:oso/9780199682201.003.0054",
    doi = "10.1093/acprof:oso/9780199682201.003.0054",
    openalex = "W4250754312",
    pages = "719-728",
    references = "doi101038nature13414, doi101073pnas1207580109, doi101086277109, doi101093gbeevq076, doi101139z04163, doi101146annurevneuro31060407125536, doi101159000079744, doi10118620419139427, doi101242dev066720, doi102108zsj231168"
}

@incollection{paululat2023acrania,
    author = "Paululat, Achim and Purschke, Günter",
    title = "Acrania (Cephalochordata) Lanzettfischchen",
    year = "2023",
    booktitle = "Metazoa - Morphologie und Evolution der vielzelligen Tiere",
    url = "https://doi.org/10.1007/978-3-662-66184-0\_10",
    doi = "10.1007/978-3-662-66184-0\_10",
    openalex = "W4376478969",
    pages = "179-188"
}

@incollection{holland2025phylum,
    author = "Holland, Nicholas D. and Holland, Linda Z.",
    title = "Phylum Chordata: Cephalochordata",
    year = "2025",
    booktitle = "Atlas of Marine Invertebrate Larvae",
    url = "https://doi.org/10.1016/b978-0-08-102871-1.00004-x",
    doi = "10.1016/b978-0-08-102871-1.00004-x",
    openalex = "W4410970159",
    pages = "793-806",
    references = "doi101006dbio20010460, doi101016jcub200804078, doi101038078267a0, doi101093plankt5115, doi101242dev12292911, doi101242dev125142701, doi101371journalpone0075461, doi103354meps130071, doi103389fcell2021668006"
}

@incollection{paululat2025acrania,
    author = "Paululat, Achim and Purschke, Günter",
    title = "Acrania (Cephalochordata, Lancelets)",
    year = "2025",
    booktitle = "Metazoa – Morphology and Evolution of Animals",
    url = "https://doi.org/10.1007/978-3-662-69904-1\_10",
    doi = "10.1007/978-3-662-69904-1\_10",
    openalex = "W4412557476",
    pages = "183-193"
}