Paleobiogeography of Cretaceous South American Mesoeucrocodylia: Contribution to the Knowledege of Biogeographical History of Gondwana and Laurasia

Abstract

Aim: Despite Mesoeucrocodylia been the most expressive faunal elements in outcrops of Gondwana, with special attention to South American basin like Bauru Group in Parana Basin and Neuquén Group in Neuquén Basin the biogeographical studies has been almost descriptive. These studies point the hypothesis that vicariance, specially the event of breakup of Gondwana, occupy a main role in speciation and diversification of Mesoeucrocodylia in Cretaceous. The present research investigates the possibility of this hypothesis been true use two complementary methods of biogeographic analysis a priori.Location: The studied reach the sedimentary basins for Gondwana and Laurassa when Mesoeucrocodylia fossils are found (South America, Africa and Eurasia continents)Methods: Brook Parsimony Analysis, with use maximum parsimony, Bayesian Binary Method for Ancestral State, a maximum like hood method to large data set, and S-DIVA to test the vicariance hypothesis. The area cladograms area time calibrating used the Temporal Calibrating GACs.Results: Allow reconstruct the ancestral area to the ancestral lineages and track the origin of “Gondwanasuchia” mesoeucrocodylian to African portion, posterior dispersion to South America. Notosuchia had an almost South American history with only peripheral ancestral reach Africa and Peirosauridae divide in two lineages, Peirosaurinae developed almost in Africa and reach South America in Early Cretaceous and Pepesuchinae an endemic South American lineage. Main Conclusions: Dispersal, not vicariance, take the main role in the diversification of the Mesoeucrocodylia during the Cretaceous. Three migration routes between drain channels take place in Early Cretaceous, one of Peirosaurinae from Araripe Basin to southern portion of South America, another from Pepesuchinae to Bauru Group and the last one of Araripesuchidae from Neuquén Basin do Araripe Basin. With the isolation of Bauru Group in Santonian a series of sympatric speciation take place in Mesoeucrocodylia lineages and other groups like titanosaurids. These sympatric events need future investigations.