Phylogeny and paleobiogeography of Cretaceous?Paleogene neobatrachian frogs

GÓMEZ, R.O.; BÁEZ, A.M.

Buenos Aires

Congreso; XXVI Jornadas Argentinas de Paleontología de Vertebrados; 2012

Universidad Maimónides-CEBBAD-Fundación de Historia Natural Félix de Azara

Neobatrachians form the most derived and diverse clade of extant frogs. The group is recorded from the Aptian onwards, but their early records are almost restricted to the southern landmasses. Although there is consensus on the monophyly of neobatrachians, their interrelationships are still debated. In order to clarify the systematic and palaeobiogeographic relationships of several Cretaceous?Paleogene neobatrachian taxa, (e.g., Estesiella boliviensis (Báez), Beelzebufo ampinga Evans, Jones, and Krause) we performed a phylogenetic analysis combining a set of 200 osteological characters and DNA sequence data (ca. 5500 pb.) from mitochondrial and nuclear genes for 120 taxa. The topology obtained is essentially congruent with previous hypotheses retrieved mainly from molecular data. Several Paleogene and Cretaceous taxa consistently emerge in nested positions within crown-group Nobleobatrachia, in contrast with the previous hypothesis of the Paleogene radiation of the latter clade. A tree reconciliation analysis (TRA) was performed for the paleobiogeographic analysis. A single optimal area cladogram was obtained, showing a split between Northern Tropical Gondwana (Tropical South America + Africa + Madagascar + India) and Southern Temperate Gondwana (Southern South America + Australia). These results show that some of the neobatrachian fossil taxa (including species from Brazil and Bolivia) are part of a distinct neotropical batrachofauna different from the coetaneous neobatrachian fauna of Patagonia (mainly represented by calytocephalellids). This integration of data has allowed us to propose a scenario for the early evolution of South American neobatrachians and explore the role of the break-up of Gondwana in shaping the frog diversity in the continent.