Postcranial remains of Notosuchus terrestris (Archosauria: Crocodyliformes) from the Upper Cretaceous of Patagonia, Argentina

POL, D.

AMEGHINIANA

Asociación Paleontológica Argentina

Lugar: Buenos Aires; Año: 2005 vol. 42 p. 21 - 38

0002-7014

Postcranial remains of Notosuchus terrestris are described here in detail for the first time. Comparison of these remains with other crocodyliform taxa revealed that Notosuchus bears numerous postcranial characters previously unknown for this group (e.g., axial prezygapophyses arising from the anterior half of the neural arch pedicels, disconnected from the neural spine; well developed suprapostzygapophyseal laminae on cervicodorsal vertebrae; poorly expanded end of ventromedial process of the coracoid; presence of a posterior process on proximal end of radiale; presence of three sacral vertebrae, being the second and third vertebrae completely fused to each other; dorsal surface of ilium flat, rugose, and lateromedially wide, lacking an iliac blade and forming a markedly extensive acetabular roof). The postcranial morphology of Notosuchus also sheds light on some paleobiological aspects of this Cretaceous crocodyliform. This include the presence of an erect hindlimb posture for this basal mesoeucrocodylian, suggesting that the sprawling locomotion appeared late during the evolution of Crocodylomorpha. Furthermore, comparisons with other forms suggest that postcranial morphology of Crocodyliformes is not as conservative as previously thought, providing a source of phylogenetic information usually overlooked in previous approaches to crocodyliform systematics.