Additional specimens of Sudamericid (Gondwanatheria) mammals from the early paleocene of Argentina

Abstract

The extinct, Cretaceous-Paleogene Gondwanatherians have previously been considered to be early xenarthrans, multituberculates and more recently Mammalia incertae sedis. However, the phylogenetic relationships of Gondwanatheria have yet to be resolved. In this paper, additional dental specimens of the gondwanatherian Sudamerica ameghinoi from the Early Paleocene Salamanca Formation of Argentina are described. These specimens provide additional information on Gondwanatheria affinities, sudamericid morphology and help support earlier hypotheses on Sudamerica dental formula and tooth categories. Sudamericid dental functional morphology and body mass estimates, based on measurements of isolated teeth, are inferred. Dental morphology such as hypsodonty, enamel microstructure and crown features do support a robust clade for Sudamericidae.: © The Palaeontological Association, 2008.