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.