Re: Ceratopsian gait

[Marcia Bell <danvarner@worldnet.att.net>]

David Krentz wrote:
> 
> Subject: Re> Ceratopsian gait                                10:44 AM
> 3/23/98
> 
>   On our movie we tried several types of walk cycles for ceratopsian
> characters ( they were the most "accurate" model we had).  I did a lot of
> reading on the subject and also had the benifit of extremely talented
> animators and excelent live action refs of various animals.  Without getting
> into too much detail, and assuring you all that all possibilities were
> explored, the semi-sprawl gait seemed to work the best.  It worked from a
> functional stand point as well as fitting into the alleged trackway.
>   Keep in mind that a CG model has a skeleton that can be assigned properties,
> so " faking it'' is not that easy.  When we added about a ten degree
> rotational arc to the scapula as the arm pushed back, it functioned much
> better than without.  Without the scapula moving SLIGHTLY the stride length of
> rear leg caused the front leg to lag a little.
>   That's my two cents, just thought I'd let you all know about my personal
> brush with " cyberpaleontology". (  Is there a legal limit for qoutation marks
> in one paragraph... I hope not).
> 
>   David Krentz
> Walt Disney Feature Animation

        I think you are on to something, David. Several months ago I was taken
to the woodshed on this list by Mr. Paul, who I deeply respect and who's
art I admire very much, on this very topic. After recovering from the
painful birching, I went over the recent literature on this topic,
including the paper by Dodson and Farlow in the new Dinofest volume.
There is a dichotomy at work here: the osteology says sprawling (I hate
that word!) and the trackways seem to say erect. I believe that the
proponents of the erect forelimb posture are not taking into account
lateral flexure of the ceratopsid body which would create footprints of
a narrower gauge than existed on the living animal. Your computer
simulations probably showed this, I hazard to guess. By the way, I just
viewed the dinosaur sequence in _Fantasia_ several times for inspiration
and I must say the gait of the Triceratops to be quite satisfying.
        Mention has been made here too of Protoceratops. There is a wonderful
articulated specimen on display at the American Museum of Natural
History, on its back with elbows way out. It is also reproduced in Lull
(1933) _Revision of the Ceratopsia_. An old mount at the Field Museum
also (unfortunately) had the femur splayed and this was the basis for
Knight's mural at that museum.
        This topic would make for a wonderful history of science thesis!
        Dan Varner