The earliest Tertiary therian mammal from South America

GOIN, F.J.; PASCUAL, R.; TEJEDOR, M.F.; GELFO, J.N.; WOODBURNE, M.O.; CASE, J.A.; REGUERO, M.A.; BOND, M.; LÓPEZ, G.; CIONE, A.L.; UDRIZAR SAUTHIER, D.; BALARINO, L.; SCASSO, R.A.; MEDINA, F.A.; UBALDÓN, M.A.

JOURNAL OF VERTEBRATE PALEONTOLOGY

The Society of Vertebrate Paleontology

Lugar: Northbrook, Illinois; Año: 2006 vol. 26 p. 505 - 510

0272-4634

We describe the oldest South American Tertiary therian mammal from Danian-equivalent strata of northwestern Chubut province, Argentina. The specimen is an isolated lower molar most likely pertaining to a polydolopimorphian marsupial, a group known from the Late Cretaceous of North America as well as later Paleocene and Eocene deposits in South America. The derived nature of this bunodont marsupial provides evidence for an evolutionary radiation of marsupials in the earliest Paleocene or Late Cretaceous of the Americas. Whereas the presence of this radiation had been suspected previously, the Lefipán specimen narrows the interval within which that radiation may have occurred.