Mesa, AZ, United States
Mesa, AZ, United States

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Gillette D.D.,Museum of Northern Arizona | Carranza-Castaneda O.,National Autonomous University of Mexico | White R.S.,Jr | Morgan G.S.,New Mexico Museum of Natural History and Science | And 3 more authors.
Journal of Mammalian Evolution | Year: 2015

North American glyptodonts originated from South American ancestors during the Great American Biotic Interchange no later than early Blancan North American Land Mammal Age (NALMA). A substantial expansion in population samples from the late Blancan 111 Ranch fauna of southeastern Arizona, several late Blancan faunas in New Mexico, and the early Blancan–Irvingtonian faunas of Guanajuato, Mexico, permit, analysis of sexual dimorphism and ontogeny of Glyptotherium texanum Osborn, 1903. Growth of carapacial osteoderms was allometric, including changes of the external sculpturing. Overall anatomy of the carapace changed with growth, with development of distinctive pre-iliac and post-iliac regions in lateral profile of adults. Skulls of adults possess a unique boss on the anterior surface of the descending process of the zygomatic arch that is not present in juveniles. Sexual dimorphism involves differences in anatomy of lateral and posterior osteoderms. Glyptotherium arizonae Gidley, 1926, is a junior synonym of G. texanum. The temporal distribution of G. texanum extends from early Blancan NALMA to Irvingtonian NALMA, with geographical distribution from Central America and Mexico to southern United States. © 2015 Springer Science+Business Media New York

Mead J.I.,East Tennessee State University | Holte S.,University of Florida | White R.S.,International Wildlife Museum | McCord R.,Arizona Museum of Natural History
Journal of Herpetology | Year: 2015

Two cranial osteoderms and a maxilla assigned to Heloderma suspectum (Squamata, Helodermatidae) were recovered from the 111 Ranch fossil locality, San Simon Valley, Graham County, southeastern Arizona. A minimum age of the deposits and fossils is approximately 2.7-2.4 million years ago, latest Blancan Land Mammal Age, spanning the Pliocene-Pleistocene boundary. The presence of a pronounced deep venom grove and a tooth count of eight indicate that the maxilla belongs to Heloderma and not the closely related and extinct Lowesaurus or Eurheloderma. The highly reduced nasolacrimal fossa and the shortened projection of the maxillary lappet on the fossil agree with the condition in H. suspectum and not in Heloderma horridum. During this transition time, the locality was a mosaic grassland-woodland ecosystem with open water and riparian niches occupied with grazing and browsing mammals. Copyright 2015 Society for the Study of Amphibians and Reptiles.

McCord R.D.,Arizona Museum of Natural History
Historical Biology | Year: 2016

Specimens of fossil Kinosternon were examined and described from the Blancan NALMA localities of Benson and 111 Ranch in Arizona. All were referred to Kinosternon arizonense. Kinosternon arizonense shares more derived characters with Kinosternon flavescens than with extant Kinosternon currently classified as Kinosternon arizonense, or any other Kinosternon species. Kinosternon stejnegeri new combination, is proposed for the extant species. © 2016, © 2015 Taylor & Francis.

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