Lagostomus telenkechanum sp. nov., a new lagostomine rodent (Caviomorpha, Chinchillidae) from the Arroyo Chasicó Formation (late Miocene; Buenos Aires Province, Argentina)

RASIA, LUCIANO LUIS; CANDELA, ADRIANA MAGDALENA

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Lugar: Lawrence; Año: 2017

0272-4634

We describe a new lagostomine rodent (Caviomorpha, Chinchillidae),Lagostomus telenkechanum sp. nov., from the Arroyo Chasicó Formation (late Miocene; Buenos Aires Province, Argentina). Three characters permit it assignation to Lagostomus: suborbital canal for the infraorbital nerve limited by a boney lamina, well developed posterior process of the palatine, and posterior maxillary foramen located at the midpoint of the M3. In addition, we identify the new species based on a unique character combination (e.g., small size, palatines reaching anteriorly the level of the midpoint of P4, anteriormargin of mesopterygoid fossa at the level of the anterior border of M3, upper cheek teeth more compressed anteroposteriorly and more obliquely implanted in the maxilla than in L. pretrichodactyla, L. compressidens and L. maximus, but less than in L. incisus, and thick cement layer in the hypoflexus). Since the early Miocene?middle Miocene genera, Prolagostomus and Pliolagostomus, are no longer recorded during the late Miocene, whereas the oldest record of the extant genus Lagostomus is recognized, we consider this period as an important turnover time in the taxonomic composition of the Chinchillidae. This study increases the understanding of the taxonomic diversity of the late Cenozoic lagostomines, contributing so to the further knowledge of the evolutionary and paleobiogeographic history of chinchillids.