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, Rio 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 during the Maastrichtian before their definitive extinction from South American and most of the world by K/P boundary. 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 Ptycheratodus, 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.
Revista del Museo Argentino de Ciencias Naturales
Apasteguia, Sebastian; Agnolin, Federico L.; and Claeson, Kerin M., "A Review of Cretaceous dipnoans from Argentina (Sarcopterygii Dipnoi) with Descriptions of New Species" (2007). PCOM Scholarly Papers. 324.