A biogeographic scenario for Rebbachisauridae, dealing with time and branch support

CARBALLIDO J. L.; POL D.; SALGADO L.

Jornada; XXVI Jornadas Argentinas de Paleontología de Vértebrados; 2012

The oldest rebbachisaurids are known from the late Early Cretaceous, but their ghost lineage suggests a Late Jurassic origin for the group. The first rebbachisaurid discoveries in Africa and South America were interpreted as evidence for a connection between both landmasses during the Cenomanian. Nevertheless, the recent discovery of rebbachisaurids in the Early Cretaceous of Europe tended to blur the biogeograophical history of the group. In order to evaluate the bioegeographic history of Rebbachisauridae, the results of a new phylogenetic analysis carried out with TNT (341 characters and 71 taxa) were analyzed through Dispersion-Extinction-Cladogenesis (DEC), a maximum likelihood methodology. This methodology allows including time information (calibrated phylogenies) and paleogeographical information (area connections). The analysis was performed allowing the terrestrial connection of Europe with Africa and Africa with South America during the Early Cretaceous and using different times for the calibration of the tree. The resulted probabilities retrieved a South American origin rebbachisaurids followed by a fast range expansion to Africa and Europe during the Hauterivian. The two clades of rebbachisaurids (Limaysaurinae and Nigersaurinae) had its origin during the Barremian-Aptian followed by a local extinction of Nigersaurinae in South America and Limaysaurinae in Europe. Nevertheless, it must be noted that the differences observed when different times are used to calibrate the phylogeny, the low branch support and absence of an earliest Cretaceous record for the group obscures the paleobiogeographical pattern. Future discoveries would help to discern if this inferred history is consequence of a sampling artifact.