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POL Diego

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Título:

Biogeographical distribution patterns during the Jurassic: new information from the Cañadón Asfalto Basin, Patagonia, Argentina

Autor/es:

POL, D.; CARBALLIDO, J.L.; RAUHUT, O.W.; ROUGIER, G.W.; STERLI, J.

Lugar:

Los Angeles

Reunión:

Congreso; 73° Annual Meeting of the Society of Vertebrate Paleontology; 2013

Resumen:

The Jurassic vertebrate fauna of the Cañadón Asfalto Basin is one of the most diverse in the world, in particular due to the highly fossiliferous Cañadón Asfalto Formation (late Early ? early Middle Jurassic). Described taxa from this unit include members of different clades of sauropod and theropod dinosaurs, heterodontosaurid ornithischians, sphenodontians, turtles, crocodylomorphs, and mammals. Recent studies on the phylogenetic affinities of these taxa have shed light on the evolutionary affinities of the taxa recorded in the Cañadón Asfalto Basin, allowing the evaluation of the biogeographic signal through quantitative methods. Several studies have suggested the existence of groups endemic to the southern hemisphere during the Jurassic whereas others have postulated a pangeic distribution as the null hypothesis for the distribution of tetrapods during this period. Here we present a series of quantitative analyses applying Dispersal Extinction Cladogenesis (DEC) in the software packages DIVA and VIP on phylogenetic hypotheses of all the above-mentioned groups in which fifteen taxa of the Cañadón Asfalto Basin (some of which have been recently published) have been included. The analyses indicate that eight eleven of the fifteen lineages recorded in the Cañadón Asfalto Basin belong to clades in which the ancestral reconstruction is restricted to the southern hemisphere, indicating the existence of a marked provincialism of these groups of vertebrates during Pangean times. Four of the taxa recorded in the Cañadón Asfalto Basin belong to lineages that, in contrast, have a non-gondwanan ancestral distribution. These results indicate the new records from the Jurassic of Patagonia are showing a previously undetected and regionalization of the distribution of continental vertebrates at least since the late Early Jurassic, before the effective separation of the northern and southern land masses. The common biogeographic pattern detected from this study suggests therefore the existence of biogeographic barriers that determined the distribution of continental vertebrates in Pangea during the Jurassic. These barriers likely were environmental or climatic, such as the postulated existence of the Central Gondwanan Desert.

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