Review of Cretaceous dipnoans from Argentina (Sarcopterygii: Dipnoi) with descriptions of new species

Abstract

In this paper we review the fossil ceratodontiform record from the Cretaceous of Argentina. We report the oldest dipnoan record from Argentina, coming from the Cenomanian of Northwestern Patagonia, Río Negro province. The species «†Ceratodus» iheringi is reassigned. Additionally, four new species are described. Ceratodontiforms were considered extinct in Laurasia after the mid-Cretaceous, with a brief «reappearance» dur-ing the Maastrichtian before their definitive extinction from South America and most of the world by K/P bound-ary. Based on our phylogenetic analysis, using characters derived primarily from tooth plates, we propose that the genus †Metaceratodus is more closely related to Neoceratodus than either is to †Ceratodus or †Ptychoceratodus, supporting prior hypotheses. In two most parsimonious trees, the two new genera here described are basal, being one of them sister taxa to Ceratodontoidea nov. and the other unresolved with respect to Protopterus.