Sphenosuchian in new issue of Nature

[bh480@scn.org]

From: Ben Creisler bh480@scn.org

This is the official reference in Nature for the news 
release posted earlier.

CLARK, J. M., XING XU, C.A. FORSTER & YUAN WANG, 2004. A 
Middle Jurassic 'sphenosuchian' from China and the origin 
of the crocodylian skull. Nature 430, 1021 - 1024 (26 
August 2004) 
The skull of living crocodylians is highly solidified and 
the jaw closing muscles are enlarged, allowing for prey 
capture by prolonged crushing between the jaws. Living 
species are all semi-aquatic, with sprawling limbs and a 
broad body that moves mainly from side-to-side; however, 
fossils indicate that they evolved from terrestrial forms. 
The most cursorial of these fossils are small, gracile 
forms often grouped together as the Sphenosuchia, with 
fully erect, slender limbs; their relationships, however, 
are poorly understood. A new crocodylomorph from deposits 
in northwestern China of the poorly known Middle Jurassic 
epoch possesses a skull with several adaptations typical 
of living crocodylians. Postcranially it is similar to 
sphenosuchians but with even greater adaptations for 
cursoriality in the forelimb. Here we show, through 
phylogenetic analysis, that it is the closest relative of 
the large group Crocodyliformes, including living 
crocodylians. Thus, important features of the modern 
crocodylian skull evolved during a phase when the 
postcranial skeleton was evolving towards greater 
cursoriality, rather than towards their current semi-
aquatic habitus.