Revueltosaurus not a dinosaur

["bh480@scn.org" <bh480@scn.org>]

From: Ben Creisler bh480@scn.org
My email has been fried for the past few days. In case this article has not
been mentioned here yet:
Proceedings: Biological Sciences 
FirstCite Early Online Publishing
  
William G. Parker , Randall B. Irmis, Sterling J. Nesbitt , Jeffrey W.
Martz , Lori S. Browne 
The Late Triassic pseudosuchian Revueltosaurus callenderi and its
implications for the diversity of early ornithischian dinosaurs
Abstract: 
A new discovery of skeletons of Revueltosaurus callenderi from the Upper
Triassic Chinle Formation of Petrified Forest National Park, Arizona
clearly shows that Revueltosaurus is not an ornithischian dinosaur as
previously supposed. Features such as the presence of a postfrontal,
crocodile-normal ankle and paramedian osteoderms with anterior bars place
R. callenderi within the Pseudosuchia, closer to crocodylomorphs than to
dinosaurs. Therefore, dental characters previously used to place
Revueltosaurus within the Ornithischia evolved convergently among other
archosaur taxa, and cannot be used to diagnose ornithischian dinosaur
teeth. As a result, all other putative North American Late Triassic
ornithischians, which are all based exclusively on teeth, are cast into
doubt. The only reasonably well-confirmed Late Triassic ornithischians
worldwide are Pisanosaurus mertii and an unnamed heterodontosaurid from
Argentina. This considerably changes the understanding of early dinosaur
diversity, distribution and evolution in the Late Triassic. 



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