SPRAWLING POSTURE

["D.W.Naish" <dwn194@soton.ac.uk>]

> 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