The youngest non-lepidosirenid lungfish of South America (Dipnoi, Latest Paleocene-Earliest Eocene, Argentina).

GOUIRIC CAVALLI, SOLEDAD; ALBERTO LUIS CIONE; GELFO, JAVIER NICOLÁS; GOIN, FRANCISCO JAVIER

San Luis

Jornada; XXV JORNADAS ARGENTINAS DE PALEONTOLOGÍA DE VERTEBRADOS; 2010

We describe the first ceratodont tooth plate from the Las Flores Formation (latest Paleocene-earliest Eocene), Chubut Province, Argentina. The material comprises a small fragmentary upper tooth plate with attached bone. This is the youngest ceratodont known from South America. In Africa, ceratodonts disappeared during the Eocene. After that they are only known from Australia, until their extinction during the Pleistocene. The extinction of non-lepidosirenid lungfishes in Africa and South America could have been related to environmental changes. Remarkably, in South America several other continental taxa became extinct during the Paleocene and Eocene: many actinopterygian families (i.e., Polypteridae, Phareodontidae, and Heterodininae) and several mammalian lineages; dryolestoids, gondwanatheres and ornithorhynchids among non-therian mammals. Among therian mammals, only the order Xenungulata was constrained to the late Paleocene and early Eocene. The material from Las Flores represents the southernmost lungfish known in the world after the K-P boundary.