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Re: Archaeopteryx gets a brain scan



Greg Paul (GSP1954@aol.com) wrote:

<Concerning Jeff's observation on the flattening of the Jehol winged 
dromaeosaurs, the same is true of the Solnhofen specimens. There probably
are  reasonably uncrushed braincases from Jehol, the type of
Sinornithosaurus might qualify.>

  Or perhaps not. Portions of the lateral braincase and occiput are
removed and "below" the frontoparietals, which have been rotated 90
degrees from the rest of the skull in *Sinornithosaurus millenii* -- it is
obliterated in "Dave." Jehol theropods with 3D skulls would likely only be
found in the lower-most, Lujiatun (Member?) sediments of the Yixian
Formation, in which lon-laminate sandstone/ash-bed clast allow for
non-squished bone to be preserved.

<But braincases have to be removed from the slab for high rez scanning.
Looking at the braincases of other bird-like theropods might not tell a
lot since they are flightless.>

  An interesting test for secondary flightlessness would be to see if a
flight-oriented brain existed in an animal that could not fly. If, as some
assume, *Archaeopteryx* was not capable of powered flight, this may very
well be a key piece; Paul, however, I know beleives Archie to be a powered
flier. If something that is know for control in a 3D environment (say,
flying or swimming, or possibly arboreal) exists in an animal that does
not in fact seem capable of being in that environment (ie., it is
terrestrial), it would appear to suggest either a part of a step-wise
increase in such features from one environment to another, or a
decrease/reversion/loss series.

  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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