New Anatomical Data on Pyrotherium (Pyrotheriidae) from the Late Oligocene of Mendoza, Argentina

Abstract

Cranial and postcranial remains of a pyrothere from Quebrada Fiera (Mendoza Province, Argentina) are herein described. A comparison with late Oligocene (Deseadan SALMA) taxa allows its identification as Pyrotherium. In morphological cranial characteristics and size, the pyrothere from Mendoza proves close to the Patagonian species, P. romeroi, and larger than P. macfaddeni from Salla (Bolivia). Contrary to the previously assumed exclusiveness of P. macfaddeni in presenting an enamel tubercle between the lobes of some teeth, the specimens from Mendoza and Patagonia share such features. The mandible of the pyrothere of Quebrada Fiera differs from that of P. macfaddeni in its more horizontal symphysis and more procumbent incisors. A number of large postcranial remains are tentatively and for the first time assigned to Pyrotherium romeroi even though the lack of data on this group prevents an accurate determination. Their assignment to other large mammals that are (homalodotheres, leontiniids) or could be (astrapotheres) present in Quebrada Fiera is discarded. Based on a previous pyrothere data matrix consisting of cranial and dental characteristics, a cladistic analysis is herein performed and three new features plus the Quebrada Fiera taxon as a terminal unit are thereafter added. The obtained results are consistent with the taxonomic determination of the studied material and do not differ in terms of the general phylogenetic relationships within Pyrotheriidae.