ZURITA Alfredo Eduardo
congresos y reuniones científicas
GLYPTOTHERIUM-GLYPTODON (XENARTHRA, GLYPTODONTIDAE, GLYPTODONTINAE): ANATOMY AND PALAEOBIOGEOGRAPHY
ZURITA, A. E; CARLINI, A. A; GILLETTE, D.
Congreso; SIXTY-EIGHTH ANNUAL MEETING- SOCIETY OF VERTEBRATE PALEONTOLOGY; 2008
SOCIETY OF VERTEBRATE PALEONTOLOGY
The clade Glyptodontidae Glyptodontinae are glyptodonts which actively participated in the Great American Biotic Interchange. During the interval late Pliocene-Pleistocene (~2.7-0.0010 Ma) it is possible to recognize two genera: Glyptodon Owen (1.07-0.008 Ma) and Glyptotherium Osborn (~3.9?-0.0010 Ma). From a palaeobiogeographic viewpoint both taxa are characterized by a great latitudinal range: Glyptodon from 47° S to 10° N; Glyptotherium from 11° N to 37° N. Despite the fact that both taxa are relatively common, no modern contributions have established morphological differentiation between them and, in fact, they are commonly wrongly identified. Preliminary studies suggest that both genera can be characterized (and differentiated) by the following characters: (1) skull: in Glyptotherium the rostral area is narrower, and the infraorbital foramina and the zygomatic process of maxilla are placed more internally than in Glyptodon; (2) morphology of the dorsal carapace: in Glyptotherium (except probably in G. texanum) the carapace has an arched (convex) dorsal profile in lateral aspect and is more highly arched than in Glyptodon,in which the carapace is lower and more elongated; in Glyptotherium, the posteriorregion is recurved upward in lateral aspect, morphology not recognized in Glyptodon;the angle between the most ventrolateral margin of the carapace and the caudal notch isapproximately of 90° in Glyptotherium, whereas in Glyptodon this angle is greater than a right angle; (3) osteoderms: in Glyptotherium the sulci that delimit the central figure are shallower and narrower than in Glyptodon; the thickness of the osteoderms is greater than in Glyptodon; the central figure of the carapacial osteoderms is flat or concave in Glyptotherium, whereas in Glyptodon this exposed surface is convex and the peripheral figures are less developed. The characters observed in G. texanum (~ 2.7 Ma) could support the idea that it belongs to a different (presently undefined) genus. On the other hand, the presence of Glyptotherium in the Pliocene (~3.9 Ma) of central Mexico must be confirmed by more precise studies.