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Re:Heterodontosaurids (was RE: Journal of Paleontology Papers)



> Lukas Panzarin wrote:
> 
> >If I'm not wrong, possible heterodontosaurids come from Portugal 
> >(Trimucrodon cuneatus),
> 
> On this topic, I'm more likely to be wrong than you are.  :-)  Though I do 
> have _Trimucrodon_ categorized as Ornithischia incertae sedis.

Trimucrodon was established as an indeterminate heterodontosaurid by 
Ruiz-Omenaca (2001) (unfortunately I don't have the right reference)..


> >and Argentina (unnamed early Carnian form, Báez et al. 1998, 2001).
> 
> Thanks - that's the one I'd forgotten (see below).
> 
> >The United States form could be a late Jurassic heterodontosaurid related 
> >to Echinodon becklesii (Galton, 2002).
> 
> This is from an SVP 2002 Abstract, isn't it?  This is based on cranial 
> material from the Morrison Formation of Fruita, Colorado.  I don't think 
> this North American _Echinodon_ has been described in print yet, and the 
> specimen may be in private hands (I'm not sure).

Exactly; this critter is out there from the mid '80, but it's current status or 
future description is (for me)ignote
> 
> There is also a report of an earlier North American heterodontosaurid, from 
> the Kayenta Formation - but I don't have the citation.

Interesting :)
 
> References
> 
> Baez, A. and Marsicano, C.A. (2001).  A heterodontosaurid ornithischian 
> dinosaur from the Upper Triassic of Patagonia.  Ameghiniana 38: 271 -279.
> 
> Abstract: Fragmentary remains of a new heterodontosaurid species, comparable 
> to _Heterodontosaurus_ Crompton and Charig, were discovered in concretions 
> in the Laguna Colorada Formation, a Late Triassic continental sequence in 
> Santa CruzProvince, Argentina.  The material consists of a weathered, left 
> posterior maxillary fragment with dentition, and, tentatively, an isolated 
> caniniformwith anterior and posterior serrations.  The preserved three 
> maxillary teeth bear flat wear facets, and are columnar and closely packed.  
> The anterior and posterior surfaces of the crowns are in contact, a feature 
> considered asynapomorphy of _Heterodontosaurus_ and _Lycorhinus_ from the 
> Early Jurassic upper Stormberg Group of southern Africa.  As in 
> _Heterodontosaurus tucki_ Crompton and Charig, the maxillary teeth lack a 
> cingulum or a constriction separating crown and root, and the wear facets of 
> adjoining teeth form a single, continuous surface.  However, the posterior 
> maxillary teeth bear more numerous and narrower ridges on their labial 
> surfaces than those of _H. tucki_.  This new record of a heterodontosaurid 
> extends the temporal range of this group of small ornithischians and, 
> considering the phylogeny of ornithischians as now understood, indicates an 
> extensive phyletic diversification of these dinosaurs in the Late Triassic.
> 
> Cheers
> 
> Tim
> 
> 
> 



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