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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.
> 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.
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