First Pyrotheria (Mammalia, Meridiungulata) from the Quebrada de Los Colorados Formation (middle Eocene–early Oligocene) at Los Cardones National Park, northwestern Argentina

We report herein a new genus and species of Pyrotheria, Berracotherium koimeterion , from the Quebrada de Los Colorados Formation (middle Eocene-early Oligocene), Salta Province (Argentina). Up to this contribution, pyrotheres had only been known from northwestern Argentina by a single fragmentary tusk referred to Propyrotherium from the Geste Formation (late Eocene), Catamarca Province. This new taxon is based on a right mandibular fragment with the roots of dp4–m1 and m2 in eruption, and it can be differentiated from other pyrotheres as follows: horizontal mandibular ramus high and robust; mandibular symphysis large that extends posteriorly to reach m1; lower cheek teeth longer than wide; m2 bilophodont; mesial and distal lophids completely separated at the labial and lingual ends; both lophids transverse, parallel, nearly straight, and low; crenulations on lophids; the cristid obliqua that connects mesial and labial lophids is conspicuous, almost perpendicular to both lophids, and it is labially placed; and well-expanded distal cingulum that forms a third lobe. A cladistic analysis was performed that recovers Berracotherium gen. nov. as a member of Pyrotheriidae and includes it within an unresolved clade with Griphodon , Propyrotherium , Baguatherium , and Pyrotherium . Berracotherium koimeterion gen. et sp. nov. increases the known diversity of Pyrotheria at both regional and global scales, as well as its geographic and stratigraphic distribution.