Boletín de la Sociedad Geológica Mexicana Volumen 67, núm. 2, 2015, p. 315-335 http://dx.doi.org/10.18268/BSGM2015v67n2a14

Description of mastodons (Mammut americanum) from the late Pleistocene of southeastern Hidalgo, central Mexico

Victor M. Bravo-Cuevas^1,*, Nuria M. Morales-García¹, Miguel A. Cabral-Perdomo¹

¹ Museo de Paleontología, Área Académica de Biología, Universidad Autónoma del Estado de Hidalgo, Ciudad del Conocimiento, Carretera Pachuca-Tulancingo km 4.5, CP 42184, Pachuca, Hidalgo, México.

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Abstract

Fossil specimens of American mastodons (Mammut americanum) that have been recovered from fluvial sedimentary deposits of the late Pleistocene of southeastern Hidalgo, central Mexico, are formally described. The sample includes cranial and postcranial remains of an adult male that represents one of the most complete mastodons that have been found in Mexico, as well as a molar belonging to an old individual. The material from Hidalgo shows the following diagnostic features of M. americanum: well-developed tusks that curved upward; upper and lower molars with a simple occlusal pattern; last molars with four to five lophs/ids; a medial sulcus between the lophs/ids; a scapula with a straight caudal border, a short and expanded neck, and a glenoid cavity that is oval in outline; a short and robust humerus with a prominent epicondylar crest; a radius with a wide distal end; and an ulna with a well-developed olecranon process and a deep trochlear notch. The dental size of the mastodon from Hidalgo is comparable to that of mastodons from the Gulf Coastal Plain and the Great Lakes region, whereas the limb dimensions are similar to those of the Watkins Glen Mastodon from the late Pleistocene of New York. In order to characterize the diet and habitat of the mastodons from Hidalgo, a stable carbon and oxygen isotope analysis in tooth enamel apatite was performed. The results indicate that studied specimens were mainly C3 browsers (mean δ¹³C isotope value of -10.06 ‰) that thrived in closed habitats covered by high vegetation, such as trees (mean δ¹⁸O isotope value of -4.31 ‰). This information suggests the presence of closed habitats in the southeastern region of Hidalgo, during the second half of the Pleistocene.

Keywords: mastodons, taxonomy, palaeoecology, Hidalgo, central Mexico.