CONICET | Buscador de Institutos y Recursos Humanos

Several systematic revisions of the Hegetotheriidae have beenpublished in the last twenty years, but some important taxonomic workremains limited to unpublished studies. In one such thesis, the lateOligocene genera Prosotherium and Propachyrucos were revised, such thatProsotherium garzoni and Propachyrucos smithwoodwardi were considered theonly valid species for each genus. Later authors loosely accepted theseinformal revisions, but recent phylogenetic coding has yet to accuratelyreflect these revisions, with character states often at odds with theknown material for these genera. This study re-examines most of thefossil material assigned to Propachyrucos and Prosotherium, includingboth published and unpublished fossils, and contributes to a betterunderstanding of the systematics, taxonomic diversity and earlymorphological evolution of the pachyrukhines. We conclude thatProsotherium garzoni and Propachyrucos smithwoodwardi are indeed the onlyvalid species for each genus, confirming the influential but unpublishedrevisions that have become widely accepted. The known material for thesespecies is clarified to aide future phylogenetic studies. At the sametime, Propachyrucos aequilatus and Pr. robustus are herein considerednomina dubia. Additionally, Miocene species originally ascribed toPropachyrucos, along with unpublished material loosely assigned to thesame genus, are here synonymized with other genera. Finally, severalfossils previously recognized as Prosotherium sp. are here recognized asP. garzoni.