Taxonomic reinterpretation of a Notoungulata Typotheria from the early Oligocene of Cañadón Blanco (Chubut, Argentina)

CERDEÑO, ESPERANZA; REGUERO, MARCELO; VERA, BÁRBARA

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2009 vol. 47

0002-7014

The Cañadón Blanco locality, in Chubut Province, is a classical Paleogene site in Patagonia with mammals mostly collected by Dr. S. Roth. As for other classical collections, precise geographic and geologic data were never recorded, and consequent­ly some problems arise. Reguero, studying the Deseadan notoungulates, made a full revision of many of these materials and synthesized the prob­lems with different localities. Concerning Cañadón Blanco, he explained that Roth provided scarce data on the localities where he recovered fossils. The specimen presented in this work is a very interesting incomplete mandible of a notoungulate presenting a set of characters that a priori could indicate different families of Typotheria, which is why it deserves a particular study. Reguero originally considered it to represent a new taxon of the Family Hegetotheriidae, but a different taxonomic interpretation is presented in this paper. The studied specimen, MLP 12-1530, is stored at the Museo de La Plata (MLP). It is an incomplete mandible with the symphysis and the anterior portions of both horizontal rami. It comes from the Cañadón Blanco locality, in Chubut Province, a classical Paleogene site in Patagonia with mammals mainly collected by Dr. S. Roth. Concerning age, Cañadón Blanco seems to correspond to the “Astraponotéen plus supérieur” of Ameghino from Gran Barranca, which is currently correlated to the Tinguirirican age.