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Unaysaurus (sauropodomorph) scapular girdle and forelimbs

Ben Creisler

A new paper:

Dilson Vargas-Peixoto, Átila Augusto Stock Da-Rosa & Marco Aurélio G.
França (2014)
Functional and biomechanic aspects of the scapular girdle and
forelimbs of Unaysaurus tolentinoi Leal et al., 2004 (Saurischia:
DOI: 10.1016/j.jsames.2014.09.024


The contribution deals with the biomechanics of the scapular girdle
and forelimbs of Unaysaurus tolentinoi, 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 return to quadrupedalism and 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.