New information on the phylogenetic relationships of Araripesuchus within Crocodyliformes

DIEGO POL; SEBASTIÁN APESTEGUÍA; FERNANDO E. NOVAS

Bozeman, Montana

Congreso; Annual Meeting of the Society of Vertebrate Paleontology; 2001

Society of Vertebrate Paleontology

Araripesuchus is a member of Mesoeucrocodylia, the most diverse clade within Crocodyliformes. This taxon has been the focus of several studies due to its distribution in Lower Cretaceous beds of Brazil and Continental Africa at the time of the South Atlantic opening. Records of this taxon have also been reported from Upper Cretaceous beds of Patagonia and Madagascar. Additional material recently collected in Upper Cretaceous beds of Northern Patagonia are presented here. These include several specimens of at least two taxa and provide new information on the phylogenetic relationships of Araripesuchus. Several hypotheses currently exist concerning the phylogenetic position of Araripesuchus. However, the merit of competing hypotheses was difficult to assess since they were based on datasets gathered with different character and taxon sampling regimes. In order to thoroughly test the phylogenetic relationships of Araripesuchus, an analysis was conducted using a broader taxon and character sampling regime. A dataset of 302 characters scored for 51 taxa was analyzed in NONA and PIWE programs. The set of most parsimonious trees found in these analyses is congruent with some results of previous phylogenetic analysis, depicting the previously known South American taxa as more closely related to each other than to the Continental Africa taxon. The new patagonian taxa reported here also cluster with the previously known South American taxa (A. gomesii and A. patagonicus). The phylogenetic position of this clade, however, is sensitive to the character weighting regime due to the high degree of conflict in its character state distribution and is extremely sensitive to taxon sampling. The new remains reported here not only broaden our knowledge on the diversity and evolutionary history of this gondwanan clade during the Cretaceous, but also provide a more informative source of biogeographic information.