A new genus and species of Proterotheriidae (Mammalia, Litopterna) from the Fray Bentos Formation (late Oligocene, Deseadan SALMA), Uruguay

The family Proterotheriidae has ancient antecedents in Uruguay, even though the accurate documentation about its diversity and distribution has only recently been organized. Currently, the record of Proterotheriidae in Uruguay has been expanded and increased, encompassing five lithostratigraphic units of various ages, ranging from late Oligocene to Early Holocene. In this work, a new genus and species, Oligopterna orientalis, is reported. This new taxon is the oldest and only late Oligocene record of the family from Uruguay, recovered from the Fray Bentos Formation. The specimen FC-DPV 2811 consists of a right mandibular fragment preserving the alveoli of dp3, enamel of the posterior lobe of dp4, and m1 erupting. The diagnostic characters of the new taxon present in the m1 are: talonid shorter than the trigonid; slim dental cusps and lophids; metaflexid deeper than the entoflexid; a conspicuous conical paraconid located mesially to the metaconid; paraconid, metaconid, and hypoconulid aligned lingually, almost at the same plane, and entoconid strongly lingually located—in front of hypoconulid in the same coronal plane—positioned out of paraconid-hypoconulid plane. This study incorporates imaging techniques and contributes to increasing the diversity of the family in the late Oligocene (Deseadan age).