Hilarcotherium castanedaii, gen. et sp. nov., a new Miocene astrapothere (Mammalia, Astrapotheriidae) from the Upper Magdalena Valley, Colombia

ABSTRACTAstrapotheria is an order of extinct South American herbivores recorded throughout the continent, from the late Paleocene to middle Miocene. Here we describe Hilarcotherium castanedaii, gen. et sp. nov., an Uruguaytheriinae astrapothere from sediments of La Victoria Formation (middle Miocene) in the Tolima Department, Upper Magdalena Valley, Colombia. H. castanedaii, represented by a partial skull, mandible, and some postcranial remains, is characterized by (1) unique dental formula, with 0/3i, 1/1c, 1/1p, and 3/3 m; and (2) lower canines with subtriangular transverse section at the base. Hilarcotherium differs from the equatorial Uruguaytheriinae genera Xenastrapotherium and Granastrapotherium in (1) having three lower incisors; (2) the diagonal implantation of the lower canines; (3) lower molars with lingual cingulid; (4) the presence of the hypocone in the third upper molar; and (5) the presence of an anterolingual pocket in the fourth upper premolar. Our phylogenetic analysis supports the mono...