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Highs and lows. What did the skull of Deinonychus look like?!



        Ann,

        This is an old old question which has been visited regularly on
the List over the years. I recall that I instigated one of the episodes
myself a while back. The sad, terrible truth of the matter is that some
workers have been making much ado about nothing.
        In Paul's earlier works, he noted the (pretty darned obvious) fact
that many past reconstructions of Deinonychus showed a skull which was too
deep. This was the result of Ostrom's early work, when he didn't have a
very good idea of how to reconstruct the skull. I suppose he used
Allosaurus as a model (not too surprising, as was one of the 
better described and illustrated theropods well up into the '80s, by 
my recollection). Ostrom is a sharp sharp cookie, but sometimes, when you
find a bunch of disarticulated elements, you really just don't know what
to do with them. I spent almost a year trying to make a atlantal neural
spine into a laterosphenoid (despite its being about 600% too thick!).
        Where was I? Paul figured out that the skull made a LOT of sense
if you used Velociraptor as a model rather then Allosaurus. In doing so,
he made the intuitive leap that maybe the nasals of D. were distorted, and
they really had a subtle concave arch, produceing a milder version of the
"racecar" snout for which V. is so famous. This sort of supposition is
fairly common in reconstructing fossil vertebrates, expecially dinosaurs,
whose thin, non-fused skull bones disarticulate and warp easily after
death. My own examination of Ostrom's figures suggests that this really
isn't that far-fetched an idea.
        This appears to have rankled a few folks, but not quite so much as
Paul's synonomization of D. with Velociraptor. Paul is a lumper (yay us!),
and while I personally don't think he went too far, many theropod workers
seemed to take the taxonomy he presented in Predatory Dinosaurs of the
World (everywhere on the List bbreviated as PDW, for those who don't
know) very badly. It may be because of this, or perhaps a belief that the
original paper is more authoritative, or perhaps simply because there are
so many mounts of Ostrom-style reconstructions in the world's museums, but
for whatever reason, Paul's reconstruction has not gained much favor in
the scientific literature, despite its popularity with artists.
        Anyway, a few years back, Maxwell and Witmer recovered some
additional material of Deinonychus a few years back. A LOT of hype was
generated about how this material demonstrated that "Paul was wrong," and
"Ostrom was right." This appears to be the source of the assumption
that Paul's reconstruction is in error.
        However, decisive as such statements seemed, reading the next
paragraph (not always a common practice, even among some of us who do
research, I am ashamed to admit) reveals that the real point of
disagreement with Paul concerned the "upturned nasals" he postulated for
Deinonychus. Maxwell and Witmer were pointing out a inaccuracy in Paul's
reconstruction, but (to my knowledge) were not condemning the whole
reconstruction.
        Looking over all of the data on dromaeosaur reconstructions, I
have to say that (as usual) I agree with Paul's reconstruction of the head
of Deinonychus, apart from the (very very slight) nasal bowing he added. I
have tried several times to do my own restoration, but I have repeatedly
quite for time reasons, and because I always get to a point where I
realize that it is looking exactly like Paul's, and Paul is a bettyer
artist than me.
        As an aside I have some problems with common reconstructions of
the skull of Dromaeosaurus, as they appear to be still based on the
original reconstruction of the skull, which was apparently modeled on the
skull of tyrannosaurids. Although dromaey does have a deep maxilla, it
is still reasonable to restore it with a somewhat more tapering,
"velociraptorine"-type snout.

        As for Paul, if you look REALLY close at the Scientific American
reconstruction, you'll see that the nasals are now restored more
conventionally. Say what you want about Paul's taxonomy, and his
reconstructions, but he tries to stay as current as possible.

        Wagner

P.S. I doubt you offended GSP, he's taken far far more flack for his
work. I suspect that he appreciates the chance to address reconstructions
in public, although I imagine work on his new book is keeping him away
from the list.