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Re: Ceratopsid controversy



Adam S Smith (sea_saur@yahoo.co.uk) wrote:

<The forelimb posture of ceratopsids seems to be unresolved. Whilst the
osteology implies (quite convincingly) a sprawling stance, this is subject
to controversy and conflicts with ichnological evidence.>

  As Paul and Christiansen have suggested, it is possible to have both a
bent-elbowed stance and a fitted ichnological record in agreement. The
manus does not sit sideways to the pes when walking, but rather inline or
slightly outward. Paul contends that the dorsal ribs and shoulder must be
correctly mounted, then Erikson's problem with *Torosaurus* will be
corrected. However, this has not been done, and is only theoretical.
During decay and burial, muscular and ligamental contractions will
undoubtedly move the scapular girdle around, rather than anchoring it, in
animals with short necks. This is due top the strong actions of the mm.
trapezius, sternohyoideus, sternomandibularis, and variuous other muscles
that, given the scapular structure, had very powerful effects on the bone.

  The story is not over yet, but the fitting of bones indicates the limb
was everted at the elbow slightly, and the real trick here is fitting
manus into track given the various shoulder positions. But not half so
headachey as fitting the outward-facing articulated sauropod manus into a
forward facing sauropod print.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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