Plateosaurus engelhardti was an Obligate Biped

Motion range of the manus of Plateosaurus engelhardti von Meyer, 1837

Authors:

Reiss et al

Abstract:

The mode of locomotion of the basal sauropodomorph Plateosaurus engelhardti, known from numerous finds from the late Triassic of Central Europe, has been extensively debated. Some early and recent research results indicate that the forelimb could not play role in quadrupedal locomotion. Other authors suggested facultative or even permanent quadrupedality. This would require adaptations of the range of motion and the stability of the manual digits to the high forces caused by locomotion. An analysis of the hyperextension capabilities of the hand can therefore determine if the manus is adapted for locomotion. This study examines the capabilities of the manus of P. engelhardti using digital 3D modeling. The motion ranges of the digits were simulated in a computer-aided engineering (CAE) program, and the hyperextension capability of the entire manus was tested.

We find that the hand of Plateosaurus was not able to support the animal during quadrupedal locomotion, but may rather have been a specialized grasping organ. Therefore, P. engelhardti must have been an obligate biped.