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Re: Burrowing/hibernating mammals have lower extinction risk





Thanks for the post Clint.  First up, just to clarify... I in no way intended 
to claim that Bakker "found" burrowing ornithopods before Varricchio et al. 
did.  All I wanted to highlight is this: the claim that _Drinker_ material was 
found in burrows was made *independently* of the published evidence supporting 
burrowing in _Oryctodromeus_.  Yes, of course Varricchio et al. deserved to get 
credit for discovering the first burrowing ornithischians; that's a no-brainer.

On the other point, I agree that it is premature to extrapolate burrowing 
behavior as extending beyond the "zephyrosaur" clade.  But it is interesting to 
*speculate*.  Here's some earlier examples, to put this in context...

http://dml.cmnh.org/2007Mar/msg00214.html
http://dml.cmnh.org/2007Nov/msg00323.html

I think it's OK to air out these (half-baked) ideas in a forum such as the DML. 
 Do I actually believe that the jugal bosses of small ornithischians were used 
to help move dirt?  Not really.  Or at least, not yet.  But it's fun to 
speculate anyway.  After all, there was a time, not so long ago, when the idea 
of flying dromaeosaurs lay completely in the realm of the imagination.


Cheers

Tim


--- On Wed, 2/4/09, clint boyd <thescelosauridae@gmail.com> wrote:

> From: clint boyd <thescelosauridae@gmail.com>
> Subject: Re: Burrowing/hibernating mammals have lower extinction risk
> To: tijawi@yahoo.com
> Cc: dinosaur@usc.edu, tholtz@umd.edu
> Date: Wednesday, February 4, 2009, 6:06 PM
> I saw this coming as soon as this thread started.
> 
> Before we begin extrapolating fossorial behavior to all
> basal ornithischians
> we should take two things into consideration.
> 
> 1) "Zephyrosaurs" or whatever you want to call
> them, have always been
> recovered as a monophyletic group whenever more than one is
> included in a
> cladistic analysis. These taxa (orodromeus, oryctodromeus,
> and zepyrosaurus)
> all share morphological features that suggest a fossorial
> lifestyle, which
> is supported in Oryctodromeus by its recovery from a burrow
> (if you haven't
> read Varricchio et al., 2007 make sure you do, its a great
> paper). These
> morphological features have NOT been recognized in more
> primitive
> ornithischians yet. Therefore, there is no support for
> extrapolating such
> behavior beyond these three taxa. In fact, extrapolating
> fully fossorial
> behavior is iffy beyond Oryctodromeus as Orodromeus lacks
> many morphological
> characters seen in Oryctodromeus and the anatomy of
> Zephyrosaurus is
> relatively poorly known.
> 
> 2) As far as Dr. Bakker's Drinker taxon, this material
> if difficult to
> include in a discussion of this topic until interested
> researchers (such as
> myself) can actually LOCATE the drinker material. Inquiries
> to many of the
> institutions he has been at over the years, inlcuding the
> one they are
> supposedly curated at, have no idea where the stuff is,
> when they'll get it
> back, nor have any data concerning them. While it would be
> interesting to
> identify fossorial behavior in more primitive
> ornithischians, other
> researchers need to be able to evaluate that evidence
> before we go that far.
> Thats the difference between Drinker and Oryctodromeus:
> Bakker CLAIMED to
> find it in burrows, Varricchio et al DEMONSTRATED AND
> PROVIDED DIRECT
> EVIDENCE that it was found in a burrow. Obviously, the
> latter is preferred.
> 
> Clint Boyd
> 
> 
> On Wed, Feb 4, 2009 at 5:37 PM, Tim Williams
> <tijawi@yahoo.com> wrote:
> 
> >
> > Tom Holtz wrote:
> >
> >
> > > > So - any burrowing dinosaurs (excluding
> birds)?
> > >
> > > "Zephyrosaurs" (a possible clade of
> hypsilophodont-grade ornithopods
> > > containing Oryctodromeus, Zephyrosaurus, and Late
> Cretaceous
> > > Orodromeus) may be burrowing dinosaurs: pretty
> secure for Orycto.,
> > > inferred for the others.  Orodromeus is present
> in the Campanian; not
> > > yet known if members of this group make it all
> the way to the boundary.
> >
> >
> > Bakker has claimed that _Drinker_, a small Late
> Jurassic ornithopod (or
> > basal cerapod), was found in burrows.  The claim was
> made long before the
> > discovery of _Oryctodroemus_.  If _Drinker_ was a
> burrowing dinosaur (and
> > AFAIK was never actually published by Bakker),
> burrowing behavior may be
> > primitive for the entire Cerapoda.  So maybe basal
> marginocephalians were
> > burrowing animals too?  It would perhaps explain those
> jugal bosses (also
> > seen in heterodontosaurids and _Changchunsaurus_).
> >
> >
> >
> > Cheers
> >
> > Tim
> >
> >
> >
> >
> 
> 
> -- 
> C. Aaroen Boyd
> PhD Candidate
> Jackson School of Geosciences
> The University of Texas at Austin
> cab@mail.utexas.edu