South American neobatrachians: A reevaluation of the Mesozoic-Paleogene fossil record

GÓMEZ, R.O.

Buenos Aires, Argentina

Congreso; I Reunión de Biología Evolutiva del Cono Sur; 2009

FCEyN, UBA - Dto. Cs. Antropológicas, FFyL, UBA - CONICET - INAPL

Most living anurans (95%) belong to Neobatrachia, a large clade of cosmopolitan distribution. The Cretaceous-lower Paleogene of South America documents the earliest records of this lineage, including those from the Early Cretaceous Crato Formation of Brazil. The majority of these remains have traditionally been considered as representing taxa related to the extant Leptodactylidae. Notwithstanding, Leptodactylidae in its traditional meaning have resulted non-monophyletic in recent phylogenetic analyses; former leptodactylids were placed in different clades of non-ranoid neobatrachians, whereas Leptodactylidae is now restricted to a few neotropical genera. Revision of the taxonomic assignments of these fossils within the new phylogenetic arrangement shows that several fossils formerly described as leptodactylids should be better considered as Neobatrachia incertae sedis, and thus, Leptodactylidae s.s. has no unambiguous Mesozoic-Paleogene record. Moreover, this new phylogenetic scheme calls for revision of many hypotheses derived from the fossil record. The present reappraisal suggests greater diversity of extinct neobatrachians in South America that previously thought and points to a more complex paleobiogeographic history of the group.