ADVANCES IN THE STUDY OF PUEBLA’S PLEISTOCENE MAMMALS: THE SANTA CRUZ LOCAL FAUNA

The continental Pleistocene of Mexico is very extensive and has yielded a large vertebrate record; however, a good part of it remains to be fully described and published on. Major flaws of many studies are the no geologic characterization of the sites, and the fossils’s lack of stratigraphic control. This is most unfortunate since the fossil vertebrate fauna registers the geologic and biologic process that played a significant role in the composition and structure of the Recent Fauna, such as the Great American Faunal Interchange, the glatiations and the extinction of many species at the end of the Pleistocene.

As far as Puebla is concerned, the finding of large fossil mammals has been frequent, yet the published papers are few and far apart. The Valsequillo Site is the best known. Ongoing research under the senior author on the geology and vertebrate paleontology of the Tepexi de Rodriguez-San Juan Ixcaquixtla-Acatlan de Osorio Area, southcentral Puebla, where Jurassic dinosaurs, Cretaceous fishes and tetrapods and Pleistocene mammals are known to occur, yielded during 2000 near Santa Cruz, Ixcaquixtla these fossils: Mammuthus sp. (molar fragments), Equus sp (molars), Glyptotherium sp. (carapace and postcraneal remains), and Sylvilagus sp. (jaw fragment with M1). These mammals are known from other localities in Puebla, and are common in the Pleistocene of Mexico.

The study area’s Quaternary crops out in the central plateau (between Tepexi and Coyotepec), the western part (Ahuatempan subarea), the eastern part (Atexcal-Tehuixtla subarea), and in fluvial channels in others. It consists of horizontal alluvial and colluvial deposits, whose thickness does not exceed 30 m. Future research besides the Santa Cruz site will involve the whole Pleistocene of the area, which will be systematically prospected and screen-washed to recover microvertebrates.