Functional and biomechanic aspects of the scapular girdle and forelimbs of Unaysaurus tolentinoi Leal et al., 2004 (Saurischia: Sauropodomorpha)

•The contribution deals with the biomechanics of the scapular girdle and forelimbs of Unaysaurus tolentinoi.•Unaysaurus tolentinoi is a sauropodomorph closer to the Plateosauridae rather than any Gondwanan form.•The material is compared to Plateosaurus and Satunalia tupiniquim.•There is a discussion on the functional (and ecological) aspects linked to the forelimb movement.

This study presents evidence about the biomechanics and forelimbs functionality of the basal sauropodomorph Unaysaurus tolentinoi (upper portion of the SM2 sequence, Santa Maria Supersequence, Upper Triassic from southern Brazil). Maximum and minimum motion angles were inferred in the joints, disregarding the presence and/or thickness of cartilage. Furthermore, processes and external structures of the bones were analyzed in attributing the functionality of forelimbs. Unaysaurus tolentinoi had well-developed grapple ability. However, the preserved elements and their osteological features are not conclusive about strictly bipedalism or quadrupedalism in U. tolentinoi.