Re: Eocursor, new basal ornithischian

[William_Parker@nps.gov]

heby@libero.it wrote:

<<Butler Richard J.,Smith Roger M. H., and Norman David B., in press. A
primitive ornithischian dinosaur from the <<Late Triassic of South Africa,
and the early evolution and diversification of Ornithischia, Proc. R. Soc.
B, 1-6

<<Nice specimen, look somewhat like a "fabrosaurid" with large hands, there
is a cladogram of Ornithischian with <<basalmost Heterodontosaurids (except
Pisanosaurus), but no mention of putative basal ornithischian like
<<Sacisaurus, Silesaurus and possible related form (Technosaurus,
Pseudolagosuchus, Eucoelophysis, ?Bromsgroveia, <<Spondylosoma,
?Caseosaurus).

Sacisaurus + Silesaurus are dinosauriforms and often referred to as
"putative basal ornithischians"; however this has never been fully tested
in a phylogenetic analysis featuring a wide diversity of taxa (including
crocodile-line archosaurs as well).  The characters in these taxa that
supposedly support a relationship with the ornithischia are based on dental
characters which can be homoplastic.  Revueltosaurus is a good example of
this and I'll never forget what Richard Butler told me when he saw the
material, that the teeth of Revueltosaurus are more "ornithischian-like"
than most ornithischians.  Are there any other characters that support a
Sacisaurus/Silesaurus + Ornithischia relationship to the exclusion of other
dinosauriforms?

Technosaurus is possibly closely related to Sacisaurus and Silesaurus and
not an ornithischian.

Pseudolagosuchus and Eucoelophysis are dinosauriforms.

Bromsgrovea is a ctenosauriscid poposaur closely related to Arizonasaurus.

Spondylosoma is non-dinosaurian and most likely a "rauisuchid".

Caseosaurus is based on an isolated ilium that shares character affinities
with basal saurischians and sauropodomorphs.



************************************************************************
Bill Parker
Vertebrate Paleontologist
Division of Resource Management
Petrified Forest National Park
P.O. Box 2217
1 Park Road
Petrified Forest, AZ 86028
(928) 524-6228 x262





Butler Richard J.,Smith Roger M. H., and Norman David B., in press. A
primitive ornithischian dinosaur from the Late Triassic of South Africa,
and the early evolution and diversification of Ornithischia, Proc. R. Soc.
B, 1-6

Nice specimen, look somewhat like a "fabrosaurid" with large hands, there
is a cladogram of Ornithischian with basalmost Heterodontosaurids (except
Pisanosaurus), but no mention of putative basal ornithischian like
Sacisaurus, Silesaurus and possible related form (Technosaurus,
Pseudolagosuchus, Eucoelophysis, ?Bromsgroveia, Spondylosoma,
?Caseosaurus).
Some feature, like a large grasping hand with well developed extensor pit
on metacarpals are probably plesiomorphic for Dinosauria, being present in
Eocursor and Heterodontosaurids.


Here you can find the pdf, although the supplementary info are not still
available...

http://www.pubs.royalsoc.ac.uk/media/proceedings_b/papers/RSPB20070367.pdf

Cheers,
Lukas Panzarin


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