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Re: Ceratopsians: sprawling or straight?



I don't know if this has been brought on the list previously,
but Johnson and Ostrom studied the problem by examining a
well-preserved, uncrushed forelimb and shoulder of Torosaurus.
By combining osteological descriptions with manipulation of a
high-fidelity cast, they concluded that the humerus was inclined
backwards and somewhat sidewards and the the elbow was flexed about
45° from the vertical: or in other words, the ceratopian forelimb
operated in a rather sprawling matter. In the same publication, they
also dismissed the trackway evidence as inconclusive (or even in
favour of the sprawling stance). They suggested this sprawling
position of the forelimb, together with the massiveness of the
shoulder girdle, was related somehow to the massiveness of the
ceratopian head.
In fact, in this way, the ceratopian gait, with a sprawling forelimb
and an erect hindlimb, is reminiscent of the gait of the large
Triassic dicynodonts, such as Kannemeyeria, Dinodontosaurus and
Stahleckeria, evenso robust animals with heavy skulls.

See:
Johnson and Ostrom: The forelimb of Torosaurus and an analysis of the
posture and gait of ceratopsian dinosaurs.
in: Functional Morphology in Vertebrate Paleontology, ed. J.J.
Thomason, Cambridge University Press 1995.

Walter: The limb posture of kannemeyeriid dicynodonts: functional and
ecological considerations.
in: The Beginning of the Age of Dinosaurs, ed. K. Padian, Cambridge
University Press 1986.

Pieter Depuydt


> >I know Greg Paul says they couldn't have sprawled because trackways
> >prove otherwise.  Good point.  But hasn't it been determined that it
> >would've been physically impossible for ceratopsians (or ceratopians,
> if
> >you're so inclined) to fit their legs under their torsos in a
> rhino-like
> >manner?  How much of this is a Bakkeristic "they were like rhinos
> >because they are cooler that way?"
> >
> >Hey, just asking.
> >
> >Larry
>
>
> Steven Czerkas claims (and has illustrated in Dinosaurs: a global view)
> that it was some kind of "high sprawl."  He also claims that articulated
> skeletons will bear this out.  The illustration shows a ceratopsian that
> is massively pigeon-toed-- his feet turn almost directly inward.  This
> doesn't seem to jive with any trackways I know of (not that I know lot).
>
>
> Joshua Dyal
> j_dyal@hotmail.com
>
>
>
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