CLADOGRAM OF THE AGNATHA AFTER JANVIER (2008a)

This is a diagram taken from Janvier 2008a. This cladogram includes the living (black) and extinct (red) “agnathan” groups. Most notable is the paraphyletic nature of the jawless fishes, a feature also seen in Benton (2005). This analysis supports the Astraspid+Heterostracan+Arandaspid clade of Benton (2005). However, it does support the isolation of the thelodonts and Anaspids despite their superficial relationships. Perhaps, the most important point of the cladogram is the Lamprey+Euphaneropid clade, a relationship for which Janvier has argued (Janvier 2006, 2007a, 2007b, 2007c, 2008a; Janvier and Arsenault 2002, 2007)

1. Animals with neural crests, epidermal placodes, and fin radials. 2. Animals with dermoskeleton in mouth and pharynx. 3. Animals with extensive dermoskeleton over much of the body. 4. Animals with an extensive lateral line system enclosed in grooves and canals, vertical semicircular canals forming loops, and a cerebellum. 5. Animals with endoskeleton lined with calcified cartilage or perichondral bone. 6. Animals with pectoral fins in postbranchial position. 7. Animals with jaws.

LITERATURE CITED Benton, M. J. 2005. Vertebrate Paleontology. Third Edition. Blackwell Publishing, Malden, MA. Janvier, P. 2006. Paleontology: Modern look for ancient lamprey. Nature. 443(7114): 921-924. Janvier, P. 2007a. Born-again hagfishes. Nature. doi:10.1038/nature05712. Janvier, P. 2007b. Primitive fishes and fishes from deep time. In: D. J. McKenzie, A. P. Farrell, and C.J. Brauner, eds. Primitive Fishes. Academic Press. San Francisco. pp 1–51. Janvier, P. 2007c. Homologies and evolutionary transitions in early vertebrate history. In: J. S. Anderson and H.-D. Sues, eds. Major Transitions in Vertebrate Evolution. Indiana University Press. Bloomington. pp 57–121. Janvier, P. 2008a. Early jawless vertebrates and cyclostome origins. Zoological Science. 25: 1045-1056. Janvier, P. and P. Arsenault. 2002. Calcification of early vertebrate cartilage. Nature. 417: 609. Janvier, P. and M. Arsenault. 2007. The anatomy of Euphanerops longaevus Woodward, 1900, an anaspid-like jawless vertebrate from the Upper devonian of Miguasha, Quebec, Canada. Geodiversitas. 29(1): 143-216.

By Jack R. Holt. Last revised: 01/13/2010