Re: Echinodon + Stenoplix

["Jaime A. Headden" <qilongia@yahoo.com>]

Rutger Jansma (fam.jansma@worldonline.nl) wrote:

<Does anyone have any pictures or information (specimens etc.) for these
genera that I could possibly have? The former one has a small skull
picture somewhere published, since I've seen it many years back in the
bookstore at the AMNH, but lacked the money back than, so I couldn't buy
the book :(>

  *Echinodon*'s cranial material has been illustrated in Glut's Dino
Encyclopedia, and the new skull material refered to this taxon from the
Morrison has been illustrated by Tracy Ford in the [most horribly outdated
and error-riven] _Dinosaur Dictionary_ by Lessem and Glut, published by
the Dinosaur Society in 1993. It's rather cute, you know....

<Currently I am working on drawings, mostly reconstructions, for my
website and of the parts that is going to air first are the basal
Ceratopsia. Everyone must be wondering what the hell that idiot from
Holland is babling about and how this relates to Echinodon, but I have
this sneeking suspicion that Echinodon might be one of the most basal one
yet. Mainly due to the presence of caniniform teeth in the premaxilla
which is also seen in the (currently) most basal Chaoyangosaurus.>

  Actually, *Echinodon* lacks a diagnostic portion of the premaxilla, so
this is unknown. The long teeth, unlike those found in various basal
ceratopians, are on the rostral _maxilla_, which is unique to dinosaurs.
The first dentary teeth are short and conical, but this is true for most
ornithischians that are not advanced marginocephalians, thyreophores, or
iguanodonts. You get it a lot in non-iguanodont Ornithopoda, basal
Thyreophora, and much of Marginocephalia. But so too in nearly every other
unaffiliated taxon (*Lesothosaurus*, *Jeholosaurus*, *Agilisaurus*, and my
fave, the cute *"Yandusaurus" multidens* (type is probably a juvenile,
which explains the excessive cuteness, of course -- I need to revise my
homepage intro picture ... grrr ... and I liked it, too ...))

---

  As for *Stenopelyx*, the original description is in German, though
Galton did a redescription with Weishampel, I think (I have been trying to
locate appropriate refs on this and may have to lament to Tracy for
help...). There is no cranial material. The postcrania is very
marginocephalian, but recent study in light of new analyses on basal
ceratopians and the basal pachycephalosaur *Goyocephale* has not been
done, and would certainly assist in the affinities of *Stenopelyx*. It
does appear to be the most basal marginocephalian, but falls outside
either Pachycephalosauria and Ceratopsia in most authors opinions that I
am aware of (Including Norman and Weishampel, Dodson, Glut, etc....) and
is thus not a true marginocephalian, but a member of the stem-clade
Marginocephalia (unnamed).

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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