The large American opossum Didelphis (Didelphimorphia, Didelphidae) in the Late Pleistocene of Uruguay, and paleoecological remarks

摘要

The fossil record of the genus Didelphis, despite its current diversity (6 species, 5 occurring in South America) and wide distribution (from southern Canada to Patagonia, Argentina), is very scarce. The oldest record of the genus in South America comes from Late Miocene sediments and the youngest records from the Late Holocene and historical times. In Uruguay, the only record is stratigraphically questionable because the material has been lost. The present contribution describes the first materials with a precise stratigraphic context assigned to Didelphis cf. D. albiventris, based on comparative morphological and numerical analysis. The materials were unearthed from several outcrops of the Sopas Formation (Late Pleistocene, northern Uruguay) and consist of an associated skull and mandible, right hemimandible, and postcranial material. These findings allow us to discuss several aspects related to the biology and ecology of Didelphis. These animals, which exhibit a mixed diet, were able to feed at intermediate levels of the food chain in highly diverse environments during the Late Pleistocene.