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Re: Scansoriopteryx as Juvenile?



Mickey Mortimer (Mickey_Mortimer111@msn.com) wrote:

<I argued these points previously in Epidendrosaurus, and will do the same
for Scansoriopteryx-
  1. Scipionyx has an ossified sclerotic ring, so these occured in very
young coelurosaurs.
  2. Scipionyx also has "distinct edges and margins of bones and processes
of them".
  3. Scipionyx has well defined carpals, while an embryonic Citipati
specimen has well defined metatarsals.
  4. Scipionyx has a well-defined coracoid tubercle.
  5. Scipionyx has well ossified vertebrae.

Scansoriopteryx may be an adult or subadult, but these features will not
show that.  What needs to be looked for are neurocentral sutures and
bone texture.>

  Though bone texture is not neccessarily observable, that there appear to
be closed neurocentral sutures in some disarticulated dorsals is apparent
to me, but I cannot back this up. However, the features above have been
used to argue for a non-neonate status for the type of *Scipionyx
samniticus*; the embryonic "Citipati" specimen (should still be
Oviraptoridae indet., a vertical rostral premax is not exactly
incontrovertible, and the status among other oviraptorids is similarly
unknown) has poorly ossified metatarsal epiphyses and they are not, as I
was hoping to show, well-defined. By well-defined, I mean the
proximal/distal ends have distinct epiphyseal ossification, lacking in the
embryo cited as well as embryos of *Lourinhanosaurus* (the allosaur, not
the "camarasaur" *Lourinhasaurus*) and the MOR "Troodon" specimens
Varricchio has recently described. *Scipionyx*, like the type of
*Sinosauropteryx*, has unfused neurocentral sutures in some vertebrae, a
lerge head, distinct epiphyses, and so forth, leading one to conlude a
differential timing of features that probably differs from extrapolated
archosaurs for which we have growth series' to compare to.

  Carr has used the bone texture that has been provided as indicative of
probable immaturity in specimens by Brochu after comparison to crocs (in
Copeia) for *Nanotyrannus*, but this seems at odds with osteological
structures and arrangements. The condition has not been found for birds so
far, and its application to dinosaurs utilizing the EPB seems
questionable.

  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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