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Re: CERATOP(S)IAN ARMS AND SEGNOSAURS
From: email@example.com (Morgan Family)
> If (a) footprints do not lie and (b) they really are ceratop(s)ian prints
> (which someone on this list - I can't remember who - recently showed is very
> and (c) the foreprints are oriented closely together with a slightly
> duck-toed angle to them, as I have heard (which might rule out even a bow-
> legged posture unless the dinosaur was fond of dislocating its wrists; the
> duck-toed condition would probably mean that the elbows were actually
> pointed inward - at least when the foot contacted the ground. Try it with
> your own arms!) I would be very interested in knowing how you fit this
> in with your theory, Rob. 8(=;u)=)
Duck-toed - nice term.
In trying it with my own arms, I found that with the elbow tucked in
near the rib cage, but not praticularly pointed inwards (in fact as
clse as I could manage to straight back), my hands naturally ended
up in just the right position to produce the trackways I saw pictures
of - slightly outside of the midline and slightly duck-toed. (At least
once I rotated my wrists to place the my palms flat to the ground).
As near as I can see, the suggestion of a horse-like gait in which the
humerus flexes slightly outward during the power stroke seems like
the most parsimonious reconstruction. This fits well with the trackways.
I *have* managed to combine a bow-legged posture with the correct hand
placement - but it *hurts* (extreme outward rotation of the wrist).
> SEGNOSAURS! Are they really still categorized as theropods? If so, why?
Somebody found a putatively intermediate form which was clearly
a theropod. This form is called Alxasaurus.
The peace of God be with you.