Re: AUSSIE ORNITHISCHIANS

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

Pete Buchholz wrote, regarding *Atlascopcosaurus*:

<<I am not sure what this is, and unfortunately it is
very fragmentary. It does seem to have teeth
indicative of Euornithopod relationships, and may even
be a real gosh-darned hypsilophodontid (though 
biogeographically, I doubt that).>>

Adam Yates wrote:

<Molnar has suggested that is a small pleisiomorphic
member of an Australian endemic "Muttaburrasauridae".
Although this is supported by just a single dental
apomorphy, I am not aware of any contradictory
evidence and the idea is very appealing (of course
that means one should be extra harsh on the idea when
seeking to test it)..>

  It is interesting to me that much of
Hypsilophodontidae is receiving more attention in the
direction to it's probable polyphyly (Rich and
Vickers-Rich, 1999, and others) and that fact that
several may clade within groups in ever more
successive levels, leading to dryomorphs. Pete knows
more about these critters than I do, so I'll leave the
features et al. to him. However, I would like to say
something on the biogeography.

  It is from my observation (and perusal of the papers
in question with plenty of conversing with friends)
that the following taxonomy appears to be the most
plausible:

Pisanosaurus mertii
`--+--Lesothosaurus australis
   `--+--Agilisaurus louderbacki
      `--+--+--Bugenasaura
         |  `--Thescelosaurus neglectus
         `--+--+--Zephyrosaurus
            |  |--Othneilia
            |  |--Laeallynasaura
            |  `--Drinker
            `--+--+--Hypsilophodon foxii
               |  |--Yandusaurus
               |  |--"Agilisaurus" multidens
               |  `--"H." weilandi
               `--+--Parksosaurus
                  |  |--Notohypsilophodon
                  |  `--Gasparinisaura
                  `--+--+--+--Tenontosaurus
                     |  |  `--Muttaburrasaurus
                     |  `--+--Atlascopcosaurus
                     |     `--Qantassaurus
                     `--+--Kangnasaurus
                        |  |--Dryosaurus
                        |  |--Antarctic dryosaur?
                        |  `--Dysalotosaurus          
                        `--+--+--Camptosaurus
                           |  `--Callovosaurus
                           `--Iguanodontia

  Some new taxa are being or are goign to be
described, some renamings, some spankin' new 'uns,
like Anabisetia, that should help to resolve
phylogenetics. Anyway, I leave one Aussie hypsie out,
*Fulgurotherium*, because as according to Vickers-Rich
and Rich (1999), Vickers-Rich et al. (1999), and Rich
and Vickers-Rich (1999) [they've been busy, haven't
they?] it is a polyphyletic assemblage of as much as
four taxa, most probably of generic distinction from
the Lightning Ridge Beast, and until those femoral
forms are sorted out, some possibly applying to named
taxa, it could be anything. I tend to think of it as a
"run of the mill" hypsie, meaning it could be a
hypsilophodontid sensu stricto, a wonderous thought.
*Thescelosaurus* may be polyphyletic, as suggested
previously on the list, and "Hypsilophodon" weilandi
could be a true hypsie, or a new genus of NA hypsie.
Holtz has commented on the NA-European
cross-im/emigration of taxa, allowing NA iguanodonts
and British and Portuguese allosauroids.

  There doesn't seem to be any endemic Aussie lineage
here, though *Tenontosaurus* could be a derived form
of an Aussie stem, and the others could form a
monophyly. I'm reconstructing the two muttaburra
skulls using the original papers and other photos as a
guide, and maybe I'll be imaginative on the missing
parts. A start for testing Yates' hypothesis should, I
think, begin with taking a good look at Tenontosaurus,
and getting the type material more properly
illustrated and thouroughly examined. An ontogeny of
the teeth should help.

  The group as a whole appears to have Gondwanan
origins, and I'm willing to bet there are
Indomadagascarese hypsies waiting for us to find. They
might be of hypsilophodontid-grade, or
othneiliid-grade, given the break up of the
continents. There, another testable hypothesis.

  I think resolution is neccesary at the agilisaur
level of the above-clade, where this taxon appears to
be right at the point of the divergence of the
ornithopods from the node cerapods and stem
marginocephalians. Understanding what it is shoudl
help considerably. I've gotten a hand on an English
translation of Dong's description of *A. louderbacki*
but have not had the time or energy to go through, as
I am trying to get a project out, and he's probably
clicking his fingers as I type this, so ...

  My opinion,


=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

Qilong---is temporarily out of service.
Check back soon.

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