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The seymouriamorph tetrapod Ariekanerpeton sigalovi from the Lower Permian of Tadzhikistan. Part II: Postcranial anatomy and relationships

Published online by Cambridge University Press:  26 July 2007

Jozef Klembara
Affiliation:
Department of Ecology, Comenius University in Bratislava, Mlynská dolina, 84215 Bratislava, Slovak Republic e-mail: [email protected]
Marcello Ruta
Affiliation:
Department of Organismal Biology and Anatomy, University of Chicago, 1027 East 57th Street, Chicago, Illinois 60637-1508, USA

Abstract

The postcranial skeleton of Ariekanerpeton sigalovi (Seymouriamorpha: Discosauriscidae; Lower Permian, Tadzhikistan) differs from that of like-sized Discosauriscus specimens in showing: wider interclavicle anterior plate with smaller, rhomboidal sculptured field on its ventral surface not reaching plate posteromedial margins; broader interclavicle plate-stem junction; slightly narrower interclavicle posterior stem; anteroposteriorly narrower clavicle ventral plate with convex posterior margin; shorter, more robust humerus; four phalanges on fourth manus digit (five phalanges in Discosauriscus); ilium more elongate dorsoventrally with anteroposteriorly narrower neck; posterior process of iliac blade oriented distinctly posterodorsally rather than horizontally; more gracile atlantal rib; broadened distal end of second presacral rib. A revised cladistic analysis of the best known seymouriamorph species retrieves Ariekanerpeton either as sister group to both species of Discosauriscus, or to D. austriacus only.

Type
Research Article
Copyright
Royal Society of Edinburgh 2005

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