Trilophosaurus - climber?

[Tim Williams <twilliams_alpha@hotmail.com>]

Spielmann, J.A., Heckert, A.B. and Lucas, S.G. (2005). The Late Triassic 
archosauromorph _Trilophosaurus_ as an arboreal climber.  Rivista Italiana 
di Paleontologia e Stratigrafia 111 (3): 395-412.

Abstract: "Two species of the unusual archosauromorph _Trilophosaurus_, _T. 
buettneri_ Case and _T. jacobsi_ Murry, are known from diverse localities in 
the Upper Triassic Chinle Group in the southwestern USA.  Both species 
likely occupied similar ecological niches, based on morphological 
similarities in the postcrania, which are essentially identical.  
_Trilophosaurus_ occurrences in the Chinle Group are relatively rare, but 
individual sites are exceptionally rich, suggesting that _Trilophosaurus_ 
lived in a different paleoenvironment than more typical Chinle vertebrates, 
which lived in or near streams (phytosaurs, metoposaurs) or on floodplains 
(aetosaurs, rauisuchians, and dinosaurs).  Two potential interpretations are 
that _Trilophosaurus_ was either an arboreal climber or a fossorial digger.  
However, the gross skeletal features of _Trilophosaurus_ are not compatible 
with a fossorial mode of life: the limbo are too long and gracile, proximal 
limb elements are longer than distal ones, and the claws are laterally 
compressed, not transversely broadened.  The intermittent study of 
_Trilophosaurus_ has caused the theory of it being arboreal, originally 
proposed by Gregory, to receive little mention in subsequent studies.  We 
reexamined the functional morphology of _Trilophosaurus_ using a qualitative 
functional morphological analysis of the skeleton, a quantitative 
examination of claw curvature, and a quantitative examination of manus/trunk 
and pes/ trunk ratios.  Claw morphology of _Trilophosaurus_ shows 
similarities to the arboreal drepanosaurs _Drepanosaurus_ and 
_Megalancosaurus_.  Our analysis provides ample evidence to suggest that 
_Trilophosaurus_ was arboreal."

I haven't seen the actual article yet.  If somebody wants to throw a pdf of 
this article my way, I'd be most appreciative.

Cheers

Tim