Evolutionary aspects of the Titanosaur Sauropods

GONZÁLEZ RIGA, BERNARDO J.

Neuquén

Congreso; III Congreso Latinoamericano de Paleontologia de Vertebrados; 2008

Universidad Nacional del Comahue

Titanosaurs were the largest terrestrial vertebrates ever to walk the earth. Their fossil record includes more than 40 species recovered from every landmass except Antartica. Most of species are represented by incomplete skeletal elements (appendicular bones, caudal vertebrae) although recent discoveries include articulated bones or cranial remains (e.g. Curry Rogers and Foster, 2001; Calvo et al., 2007a; González Riga et al., 2008). The discovery of well preserved eggs and embryos at Auca Mahuevo (Argentina) illuminates aspects of their ontogeny (Chiappe et al., 2001). New bone histological research promises to provide new insight into the growth strategies (Salgado, 2003; González Riga and Curry Rogers, 2006). In the last years, our understanding of titanosaur phylogeny has been greated enhanced by cladistic analysis (Salgado et al. 1997; Curry Rogers, 2005; Wilson, 2006). These studies agree in several points, and support the clades Titanosauria, Lithostrotia, Opisthocoelicaudinae, Aeolosaurini and Saltasaurinae. Recent papers proposed the definition of two new clades: Lognkosauria and Rinconsauria (Calvo et al., 2007a, 2007b). In spite of these relevant studies, there are some controversial aspects of their phylogenetic relationships. Moreover, the increase and reduction in body size during their evolutionary history (and the reduction of manual and pedal phalanges) are interesting subjects to analyze. In this context, we are working in a more detailed cladistic study including all new taxa recently discovered in South America (primarily Argentina and Brazil), Africa, Madagascar and India.