THE GLYPTODONT, GLYPTOTHERIUM, FROM THE PLIOCENE AND PLEISTOCENE OF NORTH AMERICA: UPDATE

ZURITA, A. E; GILLETTE, D.

Prescott, Arizona

Congreso; Western Association of Vertebrate Paleontology; 2017

Western Association of Vertebrate Paleontology

Improved samples of Glyptotherium Osborn 1903 from the 111 Ranch fauna of southeastern Arizona (Late Blancan NALMA) and Guanajuato, central México (Early Blancan NALMA) allow assessment of ontogeny of the dorsal carapace, from baby toadult. e species identi"cation for both faunas is Glyptotherium texanum (= G. arizonae), in which adults are large and robust. Previously postulated distinctions of these two species are now recognized as ontogenetic di#erences between juvenile and adult individuals. Males and females di#er in the marginal row of osteoderms of the posterior half of the dorsal carapace and caudal rings. ere are no morphological di#erences between the earliest Glyptotherium texanumfrom central México (3.9 Ma) and the 111 Ranchfauna (2.7 Ma), and no evidence that more thanone species existed in North America during the Blancan NALMA and Irvingtonian NALMA. Late Pleistocene (Rancholabrean NALMA)Glyptotherium cylindricum (= G. "oridanum and G. mexicanum) di#er from G. texanum only in the relative size of central "gures of mid-carapace osteoderms, a distinction that might be invalidated by new and better specimens. Glyptotherium is either anagenetic, with end-members G. texanum and G. cylindricum, or an example of evolutionary stasis with no evolution following the origin of this genus no later than 4 million years ago. The paleogeographic record of Glyptotherium is generally low elevation coastal plain and low reliefriparian habitats of the Gulf Coast from Central America to Florida and northward to South Carolina. New records in the interior of Méxicoindicate upland habitats and sites that are clearly situated in Paci"c drainages. To date, there are no records of glyptodonts west of the Rio Colorado(Nevada and California). Research in progress indicates clear taxonomic distinction between the South American Glyptodon and the North American Glyptotherium