Chordata

Florida lancelet Branchiostoma floridae, from here.

Belongs within: Deuterostomia.
Contains: Urochordata, Vertebrata.

The Chordata includes those animals in which the body has a notochord, a stiffening rod of cartilage running through the dorsum, during at least part of the life cycle (in vertebrates, this is replaced by the spine during embryonic development). Other synapomorphies include the presence of somites, a dorsal nerve cord, and a hypophysis (pituitary gland) (Bourlat et al. 2006). Modern molecular phylogenies support a basal position within the Chordata for the Cephalochordata, lancelets: small, superficially fish-like marine animals that primarily live buried in sand with the head exposed for filter-feeding.

<==Chordata [Acraniata, Chordonia, Euchordata]
    |  i. s.: Emmonsaspis Resser & Howell 1938 Ha62
    |           `--*E. cambrensis (Walcott 1890) [=Phyllograptus cambrensis] Ha62
    |--Cephalochordata [Acrania] BJ06
    |    |--Cathaymyrus diadexus EL11, CM98
    |    `--+--Epigonichthys BJ06
    |       |    |--E. benhami HS01
    |       |    |--E. hectori HS01
    |       |    `--E. lucayanus BJ06
    |       `--Branchiostoma BJ06
    |            |--B. belcheri BJ06
    |            |--B. floridae Hubbs 1922 C05
    |            `--B. lanceolatum [=Limax lanceolatus] G03
    `--Olfactores BJ06
         |--Urochordata BJ06
         `--+--Pikaiidae H62
            |    |--Pikaia Walcott 1911 MS16, Ho62
            |    |    `--*P. gracilens Walcott 1911 Ho62
            |    `--Oesia Walcott 1911 Ho62
            |         `--*O. disjuncta Walcott 1911 Ho62
            `--Craniata [Agnatha, Craniota, Pisces] SCM03
                 |  i. s.: Myllokunmingia SC01
                 |         Acus Müller 1774 BR05
                 |         ‘Acus’ Swainson 1839 non Müller 1774 BR05
                 |         ‘Gonostoma’ van Hasselt 1823 non Rafinesque 1810 BR05
                 |         Aetheolepis mirabilis Woodward 1895 F71
                 |         Apateolepis australis Woodward 1890 F71
                 |         Aphelepis australis Woodward 1895 F71
                 |         Madariscus robustus (Woodward 1895) [=Archaeomaene robustus] F71
                 |         Atherstonia australis Woodward 1902 F71
                 |         Belonorhynchus gigas Woodward 1890 F71
                 |         Belichthys minimus F71
                 |         Brookvalia gracilis F71
                 |         Chrotichthys gregarius (Woodward 1890) [=Pholidophorus gregarius] F71
                 |         Cleithrolepis F71
                 |           |--C. alta Woodward 1890 [=C. altus] F71
                 |           `--C. granulata Egerton 1863 [=C. granulatus] F71
                 |         Coccolepis australis Woodward 1895 F71
                 |         Corunegenys bowralensis Wade 1941 F71
                 |         Dictyopyge F71
                 |           |--D. illustrans Woodward 1890 F71
                 |           |--D. robusta Woodward 1890 F71
                 |           `--D. symmetrica Woodward 1890 F71
                 |         Enigmatichthys attenuatus Wade 1935 F71
                 |         Gosfordia truncata Woodward 1890 F71
                 |         Macroaethes brookvalei Wade 1932 F71
                 |         Myriolepis F71
                 |           |--M. clarkei F71
                 |           `--M. lata Woodward 1890 [=M. latus] F71
                 |         Tripelta dubia (Woodward 1890) [=Peltopleurus dubius] F71
                 |         Pristisomus gracilis Woodward 1890 (see below for synonymy) F71
                 |         Zeuchthiscus australis (Woodward 1890) (see below for synonymy) F71
                 |         Uarbryichthys F71
                 |           |--U. incertus Wade 1953 F71
                 |           `--U. latus Wade 1941 F71
                 |         Urosthenes latus Woodward 1931 F71
                 |         Proctotretus stantoni Girard 1854 DS89
                 |         Homalopomanus trowbridgii Girard 1856 DS89
                 |         Holconotus trowbridgii Girard 1858 DS89
                 |         Metaspriggina Simonetta & Insom 1993 MS16, W96
                 |--Haikouichthys ercaicunensis SCM03
                 `--Vertebrata BJ06

Pristisomus gracilis Woodward 1890 [incl. P. crassus Woodward 1890, P. latus Woodward 1890] F71

Zeuchthiscus australis (Woodward 1890) [=Semionotus australis; incl. S. tenuis Woodward 1908] F71

*Type species of generic name indicated

REFERENCES

[BR05] Bouchet, P., & J.-P. Rocroi. 2005. Classification and nomenclator of gastropod families. Malacologia 47 (1–2): 1–397.

[BJ06] Bourlat, S. J., T. Juliusdottir, C. J. Lowe, R. Freeman, J. Aronowicz, M. Kirschner, E. S. Lander, M. Thorndyke, H. Nakano, A. B. Kohn, A. Heyland, L. L. Moroz, R. R. Copley & M. J. Telford. 2006. Deuterostome phylogeny reveals monophyletic chordates and the new phylum Xenoturbellida. Nature 444 (7115): 85–89.

[C05] Cameron, C. B. 2005. A phylogeny of the hemichordates based on morphological characters. Canadian Journal of Zoology 83: 196–215.

[CM98] Conway Morris, S. 1998. The Crucible of Creation. Oxford University Press: Oxford.

[DS89] Dundee, H. A. & H. M. Smith. 1989. Nomenclatural eponym endings revisited. Systematic Zoology 38 (3): 279–283.

[EL11] Erwin, D. H., M. Laflamme, S. M. Tweedt, E. A. Sperling, D. Pisani & K. J. Peterson. 2011. The Cambrian conundrum: early divergence and later ecological success in the early history of animals. Science 334: 1091–1097.

[F71] Fletcher, H. O. 1971. Catalogue of type specimens of fossils in the Australian Museum, Sydney. Australian Museum Memoir 13: 1–167.

[G03] Gee, H. 2003. You aren’t what you eat. Nature 424: 885–886.

[Ha62] Häntzschel, W. 1962. Trace fossils and problematica. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt W. Miscellanea: Conodonts, Conoidal Shells of Uncertain Affinities, Worms, Trace Fossils and Problematica pp. W177–W245. Geological Society of America, and University of Kansas Press.

[HS01] Hayward, B. W., A. B. Stephenson, M. S. Morley, W. M. Blom, H. R. Grenfell, F. J. Brook, J. L. Riley, F. Thompson & J. J. Hayward. 2001. Marine biota of Parengarenga Harbour, Northland, New Zealand. Records of the Auckland Museum 37: 45–80.

[Ho62] Howell, B. F. 1962. Worms. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt W. Miscellanea: Conodonts, Conoidal Shells of Uncertain Affinities, Worms, Trace Fossils and Problematica pp. W144–W177. Geological Society of America, and University of Kansas Press.

[MS16] McCoy, V. E., E. E. Saupe, J. C. Lamsdell, L. G. Tarhan, S. McMahon, S. Lidgard, P. Mayer, C. D. Whalen, C. Soriano, L. Finney, S. Vogt, E. G. Clark, R. P. Anderson, H. Petermann, E. R. Locatelli & D. E. G. Briggs. 2016. The 'Tully monster' is a vertebrate. Nature 532: 496–499.

[SC01] Shu, D.-G., L. Chen, J. Han & X.-L. Zhang. 2001. An Early Cambrian tunicate from China. Nature 411: 472–473.

[SCM03] Shu, D.-G., S. Conway Morris, J. Han, Z.-F. Zhang, K. Yasul, P. Janvier, L. Chen, X.-L. Zhang, J.-N. Liu, Y. Li & H.-Q. Liu. 2003. Head and backbone of the Early Cambrian vertebrate Haikouichthys. Nature 421: 526–529.