Re: SPRAWLING POSTURE

[JCMcL <darwincr@laplaza.taos.nm.us>]

On Fri, 19 Jan 1996, D.W.Naish wrote:

> > That was always one of the weirder points of the sprawling ceratop 
> > theory:  The hindlimbs were supposed to be erect, but the forelimbs were 
> > supposed to sprawl.  Ceratop forelimbs are already considerably shorter 
> > than their hindlimbs, and sprawling would only have made matters worse.  
> 
> I can't help thinking about dicynodonts during all of this discussion: it's 
> well
> know, and universally accepted (ASAIK), that these animals had sprawling
> forelimbs, but erect hindlimbs. This is discussed at great length in Gillian
> King's book 'The Dicynodonts: A study in Paleobiology', and I don't have time
> to go through all the stuff discussed there here.
> 
> I don't buy the srawling model in any case, but having seen figures of
> dicynodont fore- and hindlimbs elements I'm inclined to think that 
> ceratopsians
> are doing something pretty different. Ideally, a real detailed look, comparing
> functional morphology and skeletal elements in these and other tetrapods, is
> needed. Comparisons have been drawn with ceratopsian and lizard humeri: in
> dicynodonts, the deltopectoral crest is *huge*, and in fact the whole bone's 
> got
> massive attachment surfaces, with an enormously expanded distal head and long,
> antero-posteriorly tall crests on both cranial and caudal surfaces of the
> humerus. These features are no where near as marked in ceratopsians.
> 
> "Kinda wobbily isn't he?"
> 
> DARREN NAISH
> 
I'm with Darren, here, on the ceratopsians, despite the "sprawl" of my 
infamous restoration back in the '70s.  At the time, I was working with 
the 'topsy at the American Museum of Natural History, a sprawler if there 
ever was one.  
Now, though, I feel that the topsies were erect, largely due to the fact 
observed by Darren, that the trochanters and whatnot necessary to support 
such large animals sprawled are simply not there (not to mention the 
obvious locomotion drawbacks).

I have a fairly strong wobble, meself.

Top o' the Food Chain to you all,

John McLoughlin