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Re: Ceratopsians: sprawling or straight?
At 04:17 AM 12/21/97 +0000, you wrote:
>Seems I need to address this subject, both due to the erroneus claims that
>continue to confuse the issue of ceratopsid arm posture, and to garbled
>notions regarding my work.
>Per Christansian and I are wrapping up a major MS on ceratopsian locomotion.
>It shows that their forelimbs
>were configured to work in an erect manner, with the hands directly beneath
>the shoulder joints and separated by only one and a half hand widths
>(measured from the inner edge of the hands) - as per the trackways. This is
>an essentially mammalian arrangement, for example wildebeest walk with their
>hands well separated, more so than the hindfeet.
>A few ceratopsian shoulder joints are crushed, resulting in a false lateral
>orientation to the glenoid (this includes the Milwaukee Torosaurus element
>Johnson & Ostrom studied). In uncrushed glenoids the scapular portion of the
>glenoid actually faces partly medially, hardly expected in a nonerect arm!
>There will be no presentation on this subject at Dinofest III. How do those
>wacky paleorumors start?
>The many skeletons mounted and restored with the arms more sprawling and the
>hands separated by as much as four hand widthes are mere fantasies. For
>example, the St Paul skeleton has the hands separated by three hand widthes,
>twice what the trackways record. As for the hindfeet, in the trackway they
>nearly touch on the midline, in the St Paul mount the feet are widely
>separated. IF someone seems to think their measurements confirm that the St
>Paul skeleton fits the trackways, I suggest they check their metric tape for
>accuracy, and learn some geometry along the way. As for the Milwaukee
>Torosaurus mount, it is even worse, because the feet are even further apart!
>The idea that these skeletons are in any way in accord with the best trackway
>is nonscientific, and just plain wrong. What is unfortunate is that none of
>those responsible for these skeletons is making the effort to actually
>remount them to fit the trackways.
>As that wacky paleorumor monger, I must make several points clear. I never
said that Greg would be endorsing any sprawling-type configuration of
ceratopsian frontlimb anatomy. Quite the contrary. I only said he would deal
with it. I do not think that this "garbles" notions regarding his work. I
hope it doesn't.
The "paleorumor" about a statement at DINOFEST may have been "wacky", but
it was "started" as a message to your's truly, via Email by one of the
authors. Perhaps they have changed their minds and decided not to make any
statements at the "World's Fair of Dinosaurs". I just don't know. I'm
withholding their names to protect the innocent.
Greg makes some interesting points about ceratopsian forelimb anatomy in
this post that I must admit I have not examined carefully enough. I still
find the manus imprints troubling. I also find comparison with wildebeest
anatomy a stretch. But I do have an open mind and I'm looking forward to
Greg's paper and I'm perfectly willing to admit I'm wrong...and wacky.