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Re: The tail of Jeholornis...



Tom Holtz(tholtz@geol.umd.edu) wrote:

<Although the abstract and paper call it dromaeosaurid-like, this is
probably simply an ornithologists-eye-view: it is actually a more
generalized eumaniraptoran tail (not terribly surprising, actually), more
like a troodontid or (perhaps, when we know the whole animal) _Rahonavis_,
or an elongated (in terms of number of vertebrae) _Archaeopteryx_. The
prezygapophyses (cranial zygapophyses, for those who like  the Nomina
Anatomica Avium) and chevrons (haemal arches) ARE elongate relative to
those of typical Cretaceous birds and _Archaeopteryx_, but they are NOT
the hyperelongate forms of dromaeosaurids (and in fact the zygs aren't
terribly long next to those on the distal caudals of, for example,
ornithomimids).>

  Indeed, however the chevrons do appear to have some
overlapping/interlocking morphology. It is also curious that, despite the
figure in the paper (having now read it) half the trees (from the suppl.
info) result in a sister-group relationship between *Jeholornis* and
*Rahonavis*, and variations in the tree are otherwise restricted to
neornithean ingroups. Curious stuff. Will want to compare in more
detail...

<More stuff still to come out of Liaoning, though, and not all of it
eumaniraptoran!>

  Good! I hope some of it is ornithischian, at least. I would, however,
like to see what a diverse non-theropodan fauna is present and am
presently getting ready to look at various suchians, lizards, snakes, etc.
that may be present.... If anyone could help me with the lower Jehol
Group: Yixian, Jiufotang, and Tuchengzi Formations, I would very much
appreciate it.

  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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