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Re: thoughts on the dinobirds exhibit



Adam Yates (Adam.Yates@bristol.ac.uk) wrote:

<Maybe, but the serrations on P. robusta first premax tooth are minute and
very hard to see. Are we SURE the distal edge of the 'incisor' of I.
gauthieri didn't have such features as well? (not saying it did, I simply
don't know). I don't want to extend this argument for much longer but I
will also add that contray to Jamie's comments the front of the dentary
DOES have a toothless symphyseal region.>

  I would trust Xu et al's conclusions, but until I see the teeth for
myself, as known for *Protarchaeopteryx* (which are as "hard to see" as
the denticles for *Cryptovolans* and these are obvious), I would follow
Adam in having to be cautionary of the serration comparions. However, I
need to be a little form on the nature of the teeth. The rostral most
teeth are not, as I look at very nice photos of the jaws, largest. In
fact, the _last_ premaxillary crown in *Protarchaeopoteryx* (NGMC 2125) is
largest, these decrease in diameter at the base rostrally. The medial
premaxilla expose the alveoli, and both the second and fourth crowns are
preserved, where the second is visibily smaller than the fourth. In the
dentary, a similar exposure of the alveoli lingually is exposed as well,
showing that crowns progressed forward to the very mesial tip of the
dentaries, also decreasing in size rostrally. Crown morphology is
different as well, showing that they where roughly symmetrical in section,
the crowns shaped as in some posterior maxillary and dentary crowns in
some segnosaurs (specifically, *Erlikosaurus* and *Segnosaurus*).
 
  There are insufficient reasons to consider the two taxa synonymous,
*Incisivosaurus* and *Protarchaeopteryx*. I have no preference for a
certain name, just to make this clear. I just do not see anything that
ties them together.

  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.

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