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Dino wrists (was Re: Thero palms...)
>"Thomas R. Holtz, Jr." wrote:
>> Sereno argues that all theropods from herrerasaurids on up walked
>> inward. However, having seen palm prints for probable coelophysoid
>> I suspect that the palms-inward orientation has to do more with the
>> development of the semilunate carpal block, a structure now known to
>> avetheropod, and possibly tetanurine, feature. (Note that an
>> semilunate carpal block, as seen in troodontids, oviraptorosaurs,
>> _Caudipteryx_, _Protarchaeopteryx_, dromaeosaurids, and birds, still
>> to be synapomorphic for Maniraptora).
>Regarding the diagnosis of _Compsognathus_, I am sure that some of this
>disagreement derives from the disarticulated nature of the carpal and
>elements of the _Compsognathus_ specimens, and the fact that some of
>are missing altogether. Following the discovery of the well-preserved
>_Sinosauropteryx_ specimens (four specimens in all, the last I heard),
>wrists and hands of compsognathids should be easier to assess. The
>article, written by Philip J. Currie, which is also in _The
>Dinosaurs_, includes the following passage on page 733:
>"(MANIRAPTORA) has been redefined by Holtz (1996) to include only all
>closer to birds than to ornithomimids. He went on to establish the
>Maniraptoriformes, defined as the most recent common ancestor of
>and birds and all descendants of that common ancestor (Fig. 2).
>Maniraptoriformes are characterized by a pulley-like wrist joint that
>the hand to be pulled back against the body. This characteristic was
>secondarily reduced or lost in ornithomimids and tyrannosaurids.
>discovered compsognathids (see FEATHERED DINOSAURS) have well-preserved
>that suggest that this character was more widespread among
My question is this: is there some general consensus as to the range of
wrist articulation in various theropod groups? That is, what kind of
wrist mobility is suggested for a T. rex? or an allosaurid? or a
Thanks in advance!
"Thank goodness for opposable thumbs!"
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