The first record of Galea Meyen, 1832 (Rodentia, Hystricognathi, Caviidae) in the late Pleistocene of southern Brazil and its palaeobiogeographic implications

Abstract

The first caviine rodent referable to Galea Meyen, 1832 is described from the late Pleistocene of southern Brazil based on a left dentary with the p4–m3 series. The specimen derives from the Ponte Velha I locality in the Touro Passo Creek (Touro Passo Formation, upper Pleistocene), western Rio Grande do Sul State. The main characters used to assign this specimen to Galea are: anterior area of horizontal crest at the level of prism I of p4; deep anterior area of masseteric fossa; incisor alveolus on the medial face of the dentary extended up to the level of prism II of m2; and presence of cement in the hypoflexid. Currently, the genus has a disjunct distribution, with a group in Argentina, Bolivia and Peru, and another in northern and northeastern Brazil. The presence of this taxon in Pleistocene deposits of Rio Grande do Sul State, Uruguay and the Argentine Mesopotamian, where there are no extant representatives of the genus, indicates its wider distribution during the late Pleistocene.

Key words:

• Touro Passo Formation
• rodents
• Caviomorpha
• Caviinae
• Quaternary
• Rio Grande do Sul State

Acknowledgements

We thank: the CNPq (Conselho Nacional de Pesquisa e Tecnologia) for financial support to L.K. in form of fellowship in Programa de Pós-Graduação em Geociências (UFRGS); CNPq for financial support (Universal 474485/2008-0 and PROSUL 490299/2008-3); PUCRS for the loan of the specimen; FZBRS for the infrastructure provided; Dr M. Ubilla for photos of Galea and Microcavia; Dr J. Ferigolo (MCN/FZBRS) for the discussions on the anatomy of rodents; Ricardo Duarte and Nilza Dornelles (Cabanha Touro Passo) and Adolfo Martins de Menezes Filho (Fazenda Cinco Palmas) for help with field work; Dra. M.E. Pérez for the information about the homologies of the mandibular crests in Cavioidea; Dra. A. Bezerra, for the unpublished information about the living Galea; Drs D. Verzi, M.G. Vucetich, C. Deschamps, I. Olivares (MLP), J.A. Oliveira and S. Franco (MN) for the access to collections under their care; and the editors of Alcheringa and reviewers M.G. Vucetich and M.M. Ballesteros, for their useful comments that improved the manuscript.