A SPECIES OF THE AUSTRALIAN LUNGFISH GENUS METACERATODUS IN UPPER CRETACEOUS BEDS OF SOUTH AMERICA

ALBERTO LUIS CIONE & SOLEDAD GOUIRIC-CAVALLI

Mexico

Congreso; Mesozoic Fishes 5; 2010

Four species of the ceratodontid lungfish genus Metaceratodus (M. ellioti, M. bonei, M. wollastoni) were described in Australia from sediments that range from the Lower Cretaceous to Pleistocene. These species were identified with isolated plates, some joined to splenial and prearticular bones. Other authors have suggested that the species Metaceratodus wollastoni could be present in South America. Here we confirm the occurrence of specimens of Metaceratodus from Upper Cretaceous beds of northern Patagonia (provinces of Río Negro and Neuquén) and Cuyo (province of Mendoza), Argentina. However, we do not agree in recognizing an Australian species in South America but a different one. We used many isolated tooth plates and several others attached to bone and different ontogenetic stages. Metaceratodus shares with Ceratodus broad and flat tooth plates, which present robust ridges originated anteriorly (not medially). However, they differ from those of Ceratodus because Metaceratodus presents double prearticular sulcus (not single). Besides, Ceratodus appears to be a boreal genus. The Patagonian material we here describe presents the Metaceratodus character. The occurrence of Metaceratodus in the South American Upper Cretaceous confirms the existence of fresh water basin connection between both continents by means of Antarctica during the Cretaceous. This continental connection is also confirmed by other organisms as well as by tectonic evidence.