Re-assessment of the Oligocene genera Prosotherium and Propachyrucos (Hegetotheriidae, Notoungulata)

SEOANE, F.; CERDEÑO, E; SINGLETON, H.

COMPTES RENDUS PALEVOL

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2019 vol. 18 p. 643 - 662

1631-0683

Severalsystematic revisions of the Hegetotheriidae have been published in the lasttwenty years, but some important taxonomic work remains limited to unpublishedstudies. In one such thesis, the late Oligocene genera Prosotherium and Propachyrucoswere revised, such that Prosotheriumgarzoni and Propachyrucossmithwoodwardi were considered the only valid species for each genus. Laterauthors loosely accepted these informal revisions, but recent phylogeneticcoding has yet to accurately reflect these revisions, with character statesoften at odds with the known material for these genera. This study re-examinesmost of the fossil material assigned to Propachyrucosand Prosotherium, including bothpublished and unpublished fossils, and contributes to a betterunderstanding of the systematics, taxonomic diversity and early morphologicalevolution of the pachyrukhines. We conclude that Prosotherium garzoni and Propachyrucossmithwoodwardi are indeed the only valid species for each genus, confirmingthe influential but unpublished revisions that have become widely accepted. Theknown material for these species is clarified to aide future phylogeneticstudies. At the same time, Propachyrucosaequilatus and Pr. robustus areherein considered nomina dubia. Additionally,Miocene species originally ascribed to Propachyrucos,along with unpublished material loosely assigned to the same genus, are heresynonymized with other genera. Finally, several fossils previously recognizedas Prosotherium sp. are hererecognized as P. garzoni.