Hostname: page-component-8448b6f56d-jr42d Total loading time: 0 Render date: 2024-04-23T21:28:56.552Z Has data issue: false hasContentIssue false

How chordates and echinoderms separated from each other and the problem of dorso-ventral inversion

Published online by Cambridge University Press:  21 July 2017

R. P. S. Jefferies*
Affiliation:
The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom
Get access

Abstract

It is now possible to reconstruct what happened when the chordates and echinoderms first split from each other. This involves a three-way comparison among: 1) the solute Coleicarpus, which is probably a stem-group dexiothete; 2) the Cincta, which seem to be the least crownward known echinoderms; and 3) the solute Castericystis, which is a stem-group chordate, probably the least crownward known. Counter-torsion of the tail, by which the effects of dexiothetism were nullified in the tail, took place in two phases, firstly in the fore tail and later in the hind tail. Echinoderms and chordates are descended from ancestors that were attached to, or lay on, the sea floor and were therefore much more liable to attack from above than beneath. This probably explains why the main nerve trunk in chordates is dorsal, rather than being ventral as in protostomes.

Type
Research Article
Copyright
Copyright © 1997 by The Paleontological Society 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ax, P. 1987. The Phylogenetic System. John Wiley, Chichester, England, 340 p.Google Scholar
Brien, P. 1948. C—Embranchement des Tuniciers, p. 553930. In Grassé, P.-P. (ed), Traité de Zoologie. Tome XI. Échinodermes, Stomochordés, Prochordés. Masson, Paris, 1077 p.Google Scholar
Daley, P. E. J. 1992. The anatomy of the solute Girvanicystis batheri (?Chordata) from the Upper Ordovician of Scotland and a new species of Girvanicystis from the Upper Ordovician of South Wales. Zoological Journal of the Linnean Society, 105:353375.Google Scholar
Daley, P. E. J. 1995. Anatomy, locomotion and ontogeny of the solute Castericystis vali from the Middle Cambrian of Utah. Géobios, 28:585615.Google Scholar
Daley, P. E. J. 1996. The first solute which is attached as an adult; a Middle Cambrian fossil from Utah with echinoderm and chordate affinities. Zoological Journal of the Linnean Society, 117:403440.CrossRefGoogle Scholar
Friedrich, W.-P. 1993. Systematik und Funktionsmorphologie mittelkambrischer Cincta. Beringeria, 7:3190.Google Scholar
Hennig, W. 1969. Die Stammesgeschichte der Insekten. Kramer, Frankfurt-am-Main, 436 p.Google Scholar
Hogan, B. L. M. 1995. Upside-down ideas vindicated. Nature, 376:210211.Google Scholar
Holland, N. D. 1991. Chapter 4. Echinodermata: Crinoidea, p. 247299. In Giese, A. C. and Pearse, J. S., Reproduction in Marine Invertebrates. Academic Press, New York.Google Scholar
Holley, S. A., Jackson, P. D., Sasai, Y., Lu, B., De Robertis, E., Hoffman, F. M., and Ferguson, E. L. 1995. A conserved system for dorsal-ventral patterning in insects and vertebrates involving sog and chordin. Nature, 276:249253.Google Scholar
Jefferies, R. P. S. 1979. The origin of chordates—a methodological essay, p. 443477. In House, M. R. (ed.), The Origin of Major Invertebrate Groups. Systematics Association Special Volume 12, 515 p.Google Scholar
Jefferies, R. P. S. 1986. The Ancestry of the Vertebrates. Cambridge University Press and British Museum (Natural History), London, 376 p.Google Scholar
Jefferies, R. P. S. 1990. The Solute Dendrocystoides scoticus from the Upper Ordovician of Scotland and the ancestry of chordates and echinoderms. Palaeontology, 33:631679.Google Scholar
Jefferies, R. P. S., and Brown, N. A. 1995. Dorsoventral axis inversion? Nature, 374:22.CrossRefGoogle ScholarPubMed
Jefferies, R. P. S., Brown, N. A., and Daley, P. E. J. 1996. The early phylogeny of chordates and echinoderms and the origin of chordate left-right asymmetry and bilateral symmetry. Acta Zoologica (Stockholm), 77:101122.Google Scholar
Katsuyama, Y., Wada, S., Yasugi, S., and Saiga, H. 1995. Expression of the labial Group Hox Gene HrHox-1 and its alteration induced by retinoic acid in development of the ascidian Halocynthia roretzi. Development, 121:31973205.CrossRefGoogle ScholarPubMed
Lester, S. M. 1985. Cephalodiscus sp. (Hemichordata: Pterobranchia): observations of functional morphology, behavior and occurrence in shallow water around Bermuda. Marine Biology, 85:263268.Google Scholar
McGinnis, W., and Krumlauf, R. 1992. Homeobox genes and axial patterning. Cell, 68:283302.Google Scholar
Meyer, D. L. 1979. Length and spacing of the tube feet in crinoids (Echinodermata) and their role in suspension-feeding. Marine Biology, 51:361369.Google Scholar
Nelsen, O. E. 1953. Comparative Embryology of the Vertebrates. Constable, London, 982 p.Google Scholar
Nübler-Jung, K., and Arendt, D. 1994. Is ventral in insects dorsal in vertebrates? Roux' Archives for Developmental Biology, 203:357366.Google Scholar
Paterson, C., and Rosen, D. E. 1977. Review of the Ichthyodectiform and other Mesozoic teleost fishes and the theory and practice of classifying fossils. Bulletin of the American Museum of Natural History, 158:85172.Google Scholar
Paul, C. R. C., and Smith, A. B. 1984. The early radiation and phylogeny of echinoderms. Biological Review, 59:443481.CrossRefGoogle Scholar
Sprinkle, J. 1973. Morphology and Evolution of Blastozoan Echinoderms. Museum of Comparative Zoology, Harvard University, Special Publication, 283 p.Google Scholar
Ubaghs, G. 1968. Homostelea, p. S565S581. In Moore, R. C. (ed.), Treatise on Invertebrate Paleontology, Part S. Echinodermata 1 (2). The Geological Society of America and University of Kansas Press, Lawrence, Kansas.Google Scholar
Ubaghs, G., and Robison, R. A. 1985. A homoiostelean and a new eocrinoid from the Middle Cambrian of Utah. University of Kansas Paleontological Contributions Paper, 115:124.Google Scholar
Ubaghs, G., and Robison, R. A. 1988. Homalozoan echinoderms of the Wheeler Formation (Middle Cambrian) of western Utah. University of Kansas Paleontological Contributions Paper, 120:117.Google Scholar
Van der Horst, C. J. 1927–1939. Hemichordata. In Bronn, W., Klassen und Ordnungen des Tierreichs, Bd. 4, Abt. 4, Buch 2, Teil 2. Leipzig, 737 p.Google Scholar
Wada, H., Holland, P. W. H., and Satoh, N. 1996. Origin of patterning in neural tubes. Nature, 384:123.Google Scholar