Fossil Sirenia (Mammalia: Dugongidae) from the Pirabas Formation (Early Miocene), northern Brazil.

Abstract

The Pirabas Formation on the Atlaniic coast of Pará, Brazil, is evidently of late Early Miocene (Burdigalian) age. It has recently yielded material of three genera ofdugongid sirenians: Dioplotherium cf. D. allisoni cf. and Rytiodus (Subfamily Rytiodontinae), and cf. Metaxyltherium (Subfamily alitheriinae). If the specimen tentalively referred to Rytiodus is correctly identified, this is the first record of the genus in the New World. Sírenotherium pírabense, based on material previously reported from the Pirabas Formation, is a nomen dubium. The new discoveries include the most complete fossil sirenian remains yet discovered in South America, and show that Early Miocene sirenian diversity on the Atlantic coast of South America was comparable to that which existed contemporaneously in North America.