Oa. Lebedev et Mi. Coates, THE POSTCRANIAL SKELETON OF THE DEVONIAN TETRAPOD TULERPETON CURTUM LEBEDEV, Zoological journal of the Linnean Society, 114(3), 1995, pp. 307-348
Postcranial remains of the Russian Late Devonian tetrapod Tulerpeton i
nclude the hexadactylous fore limb, hind limb, anocleithral pectoral g
irdle, squamation, and associated disarticulated postcranial bones. A
cladistic analysis indicates that Tulerpeton is a reptiliomorph stem-g
roup amniote and the earliest known crown-group tetrapod: Acanthostega
and Ichthyostega are successively more derived plesion stem-group tet
rapods and do not consititute a monophyletic ichthyostegalian radiatio
n. Previous analyses suggesting a profound split in tetrapod phylogeny
are thereby corroborated, and likewise the interpretation of Westloth
iana as a stem-group amniote. The divergence of reptiliomorphs from ba
trachomorphs occurred before the Devonian-Carboniferous boundary. Tule
rpeton originates from an entirely aquatic environment with a diverse
fish fauna. The morphologies of its limbs and those of Devonian stem-t
etrapods suggest that dactyly predates the elaboration of the carpus a
nd tarsus, and that polydactyly persisted after the evolutionary diver
gence of the principal lineages of living tetrapods. The apparent abse
nce of a branchial lamina and gill skeleton suggests that Tulerpeton w
as primarily air-breathing, whereas contemporary stem-group tetrapods
and more recent batrachomorphs retained greater emphasis on gill-breat
hing. (C) 1995 Academic Press Limited