The Carboniferous amphibian Tuditanus (Eosauravus) and the distinction between microsaurs and reptiles. American Museum novitates ; no. 2337

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New York, N.Y. : American Museum of Natural History
"The genus Tuditanus (Eosauravus) from the Middle Pennsylvanian of Linton, Ohio, is redescribed on the basis of the two type specimens, neither of which had previously been prepared. This animal, which has been considered alternatively a microsaurian amphibian and a primitive reptile, proves to be a microsaur having these characteristics: sculptured skull roof with orbits lying at mid-length and palpebral cups; about 25 isodont marginal teeth; postparietals occipital in position; 29 presacral vertebrae; ilium with dorsal and posterior processes; stout limbs with entepicondylar foramen in humerus; tetradactyl manus with phalangeal count of 2, 3, 4, 3; pentadactyl pes with astragalus and calcaneum and a phalangeal count of 2, 3, 4, 5, 4; and hoe-shaped ungual phalanges. Tuditanus is clearly a member of the central group of microsaurs, although it shows a number of terrestrial adaptations similar to those observed in captorhinomorph reptiles. The anatomy of all microsaur genera is reviewed in order to determine whether any members of this group might be related to the ancestry of reptiles. The following features are found to be characteristic of all microsaurs, and to distinguish them from reptiles: (1) the presence of no more than a single bone in the temporal series; (2) the absence of a transverse flange from the pterygoid; (3) the concave occipital condyle articulating with a single specialized cervical vertebra; (4) the absence of trunk intercentra; and (5) the oval dorsal scales with radial striations superimposed on a concentric growth pattern. These features indicate that microsaurs could share a common ancestry with reptiles only at, or near, the level of the rhipidistian fish and only in pre-Carboniferous time"--P. 46-47.
50 p. : ill. ; 24 cm.
Includes bibliographical references (p. 47-50).