Pleistocene cetacean fossils from the coastal plain of Rio Grande do Sul in southern Brazil

Abstract

Cetacean ear bones are useful for palaeontological studies because it is possible to identify most species based on their gross morphology, and thus glean information about past occurrences and distributions. This study describes cetacean tympanic bullae and periotics preserved in Middle–Late Pleistocene coastal barrier systems from Rio Grande do Sul in southern Brazil. The specimens were collected ex situ on the modern beach, and reveal the presence of the Franciscana dolphin, Pontoporia blainvillei, an indeterminate delphinid, the rorqual whale, Balaenoptera, and right whale, Eubalaena. Given the current diversity of dolphins and whales in the Atlantic Ocean, these fossils suggest that the reported diversity of Pleistocene cetaceans is probably underestimated. The barrier systems of Rio Grande do Sul are the only Brazilian deposits that have preserved Pleistocene cetacean remains to date.

Thayara Silveira Carrasco* [[email protected]], Laboratório de Estratigrafia e Paleontologia and Programa de Pós-graduação em Biodiversidade de Ambientes Costeiros, Instituto de Biociências, Campus do Litoral Paulista, Universidade Estadual Paulista, 11330-900 São Vicente, SP, Brazil; Francisco Sekiguchi Buchmann [[email protected]], Laboratório de Estratigrafia e Paleontologia, Instituto de Biociências, Campus do Litoral Paulista, Universidade Estadual Paulista, 11330-900 São Vicente, SP, Brazil.

Keywords:

• Mysticeti
• Odontoceti
• tympanic bulla
• periotic
• petrosal
• Quaternary marine deposits

Acknowledgements

We thank Ana Maria Ribeiro (Museu de Ciências Naturais) for access to collections. The Paleontological Society (especially Lee Cone), Robert Boessenecker, Michelangelo Bisconti, and Paulo César Simões-Lopes assisted with the taxonomic identifications. Erick Cruz reviewed a previous version of this manuscript. Erich Fitzgerald, an anonymous reviewer, and Alcheringa Editors Benjamin Kear and Stephen McLoughlin contributed critical reviews that improved the quality of our paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

T.S.C. received a scholarship from the Coordination for the Improvement of Higher Education Personnel – Brazil (CAPES) (88882.436025/2019-01).