Morphometric approach to Titanosauriformes (Sauropoda, Dinosauria) femora: Implications to the paleobiogeographic analysis

Abstract

A morphometric approach to Titanosauriformes sauropod dinosaur femora pro-vides an interesting tool for systematic and paleobiogeographic studies. The femur is an element of phylogenetic interest, being the proximal one third deflected medially or lateral bulge one of the autapomorphies of Titanosauriformes. Some of the selected 20 landmarks use to be reference anatomical points for the femur measurements, yet never attempting to apply for the Geometric Morphometrics. The landmarks are located at the posterior femora outline, except for the fourth trochanter that is a medial projection of this feature. The Procrustes Superimposi-tion Analysis reveals that there are differences among some Titanosauriformes clades, for instance between the Titanosauria from Laurasia and Gondwana. This may indicate they separate at the end of the Jurassic times, when supercontinents were the Pangea, and it is unnecessary to resort to intercontinental bridges during the Upper Cretaceous to explain the existence of Titanosauria in Laurasia