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

ADRIANA CANDELA, MARCOS CENIZO, DANIEL TESSARA, LUCIANO RASIA, CELINE ROBINET, NAHUEL MUÑOZ, CAROLA CAÑON, ULYSES PARDIÑAS

JOURNAL OF PALEONTOLOGY

PALEONTOLOGICAL SOC INC

Lugar: CAMBRIDGE; Año: 2019

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 southeastern Buenos Aires Province (Central Argentina). Phylogenetic analyses allow us to proposethat the new species described here and the already known Eurzygomatomys mordax (Winge) represent a new genusclosely related to the living Euryzygomatomys spinosus and Clyomys laticeps. The new genus differs from Euryzygomatomys and Clyomys by having much more procumbent upper incisors, a more developed fossa for the M. temporalis, moreflared and laterally expanded zygomatic arches, frontal less markedly expanded posteriorly, jugals much deeper anteriorly than posteriorly, with the dorsal border descending more abruptly posteriorly, smaller orbital cavity, and externalauditory meatus relatively smaller and slanted upward and backward. Several features of the new species reflect a higherdegree of adaptation to semifossorial habits than those of E. spinosus. The origin of the semifossorial ecomorphotypewithin echimyids may have been triggered by the expansion of relatively open and arid environments that arose nearthe Miocene-Pliocene boundary. The record of this new echimyid in Central Argentina indicates that during the earlyPleistocene, 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.