New Mexico Geological Society Annual Spring Meeting — Abstracts

Isolated teeth from the lower third of the upper shale member of the Chinle Formation in east-central New Mexico represent at least on taxon of anchisaurid prosauropod. Two distinct tooth morphologies are present. The first type consists of laterally compressed teeth up to 13 mm in height, 6 mm in width, and 9 mm in length. Both anterior and posterior margins of the teeth bear up to 15 coarse serrations which are at angles from 90 degrees to 45 degrees to the tooth margin. Above the root the teeth broaden before tappering to a point. Someteeth are poorly recurved and some bear faint longitudinal striations. Terminal and lateral wear facets are apparent on some teeth. These teeth un-doubtedly represent prosauropod dinosaurs because of their shape, size, and morphology of serrations and are most similar to maxillary and dentary teeth of the anchisaurid Plateosaurus. A second type is represented by triangular laterally compressed teeth, which are up to 9 mm in height, 4mm in width, and 6 mm in length. Up to 10 coarse serrations, angles at about 45 degrees, are present on the anterior and posterior margins of the teeth. A distinct median range is evident on the lateral aspect of these teeth. Some specimens show terminal and lateral wear facets. The roots are narrower than the bases of the crowns. The tooth shape, serration morphology, and presence of median ridges indicate that these teeth represent herbivorous dinosaurs. In size these teeth resemble prosauropods, but in morphology they are most similar to smaller fabrosaurids and some later stegosaurs, such as Huangosaurus. At least the first of these two types of tooth morphology represents an anchisaurid prosauropod. Prosauropods are unknown in the Late Triassic of North America but are common in some rock units of that age in South America, Europe, China, and Africa.