Titanosaurian in Chile and its Phylogenetic and Biogeographical Context

Abstract

An overview of the titanosaur fossil record in Chile is presented here along with the phylogenetic and paleogeographical implications of these findings. A phylogenetic approach, based on a review of the most complete data bases for Sauropoda and Titanosauria, shows that the Chilean specimens can be included like saltasaurids in the clade Lithostrotia, which includes the most recent common ancestor shared between Saltasaurus and Malawisaurus and all its descendents. The consistence and robustness analysis of this clade shows that the ingroup relationships are yet controversial, although the clade itself is stable, and that the greater stability is centered at the level of the clade Lithostrotia. The composition of various clades of the ingroup such as Saltasauridae, Saltasaurinae and Opisthocoelicaudiinae sensu stricto results to be variable depending on the data used. These analyses have direct effects on the biogeographic hypotheses: resulting topologies are consistent with a dispersion model of distribution. The Chilean taxa share, with the other Lithostrotia, an alternated geographic distribution compared to its position in the cladogram. In this way, is possible to find these taxa mixed, in a same shared node, with other South American species as well as specimens from North America, India, Africa, Madagascar, Asia and Europe.