A marsupial assemblage (Mammalia, Didelphimorphia) from the Quaternary of the Serra Da Capivara, State of Piauí, Brazil

Abstract

Didelphimorphia is one of the three extant marsupial orders in South America, and the only one currently found in Brazil. These marsupials have a wide variety of habits and occupy different habitats, making them good indicators of paleoenvironmental conditions. The Serra da Capivara National Park, located in the municipalities of Sao Raimundo Nonato, Coronel Jose Dias, Joao Costa and Brejo do Piaui, in the southeast of the State of Piaui, contains a large number of karstic caves and rock shelters in which hundreds of fossils of Pleistocene mammalian megafauna have been collected, together with small mammal fossils. This study reveals the diversity of didelphids in the Serra da Capivara through the analysis of fragmented maxillae and dentaries found in four paleontological sites: Toca do Serrote das Moendas, Toca do Gordo do Garrincho, Toca do Serrote do Artur and Toca do Barrigudo. The fossils were attributed to six taxa: Monodelphis domestica, Monodelphis americana, Didelphis albiventris, Cryptonanus agricolai, Gracilinanus agilis and Thylamys karimii. They constitute new records for the Quaternary of the Serra da Capivara, except for M. domestica and D. albiventris. Despite the megafauna indicating a Pleistocene age, radiocarbon dating of bioapatite from specimens of small mammals (marsupials and rodents) resulted in Holocene ages (5,550 ± 40 years BP to 1,670 ± 25 years BP), showing temporal mixing in the studied sites. All the taxa described here are currently found in the Caatinga, suggesting stability in the taxonomic composition of the didelphid assemblage, at least since the Middle Holocene.