A new echimyid genus (Rodentia, Caviomorpha) in Central Argentina: uncovered diversity of a Brazilian group of mammals in the Pleistocene

TASSARA, DANIEL; MUÑOZ, NAHUEL A.; CANDELA, ADRIANA M.; RASIA, LUCIANO L.; VALENZUELA, CAROLA CAÑÓN; CENIZO, MARCOS; ROBINET, CÉLINE; PARDIÑAS, ULYSES F. J.; TASSARA, DANIEL; MUÑOZ, NAHUEL A.; CANDELA, ADRIANA M.; RASIA, LUCIANO L.; VALENZUELA, CAROLA CAÑÓN; CENIZO, MARCOS; ROBINET, CÉLINE; PARDIÑAS, ULYSES F. J.

JOURNAL OF PALEONTOLOGY

PALEONTOLOGICAL SOC INC

Lugar: Lawrence; Año: 2020 vol. 94 p. 1 - 15

0022-3360

We describe a new extinct spiny rat, Proclinodontomys dondasi n. gen. n. sp. (Rodentia, Caviomorpha, Echimyidae), represented by a noteworthy preserved skull and mandible from the early-middle Pleistocene outcrops at thecoastal cliffs of SE Buenos Aires Province (Central Argentina). Phylogenetic analyses allow us to propose that thenew species described here and the already known Eurzygomatomys mordax (Winge) represent a new genus closelyrelated to the living Euryzygomatomys spinosus and Clyomys laticeps. The new genus differs from Euryzygomatomysand Clyomys by having much more procumbent upper incisors, a more developed fossa for the M. temporalis, more flaredand laterally expanded zygomatic arches, frontal less markedly expanded posteriorly, jugals much deeper anteriorly thanposteriorly, with the dorsal border descending more abruptly posteriorly, smaller orbital cavity, and external auditorymeatus relatively smaller and slanted upward and backward. Several features of the new species reflect a higher degreeof adaptation to semifossorial habits than those of E. spinosus. The origin of the semifossorial ecomorphotype withinechimyids may have been triggered by the expansion of relatively open and arid environments that arose near the Miocene-Pliocene boundary. The record of this new echimyid in Central Argentina indicates that during the early-middlePleistocene, the southern limit of the geographic range of extinct representatives of the Brazilian lineage of semifossorialechimyids extended farther south than that of their living members.