Re: Oviraptor

["Jaime Headden" <ja_headden@qilong.8m.com>]

Tim Williams (twilliams_alpha@hotmail.com) wrote:

<Lü (2002) distinguish _Heyuannia_ from _Ingenia_ by the fusion of metacarpals I
and II to each other and to the semilunate carpal (i.e., an incipient
carpometacarpus); the presence of an additional sacral vertebra (to give a total
of eight, compared to seven in _Ingenia_); and the overall shape of the ilium
(iliac postacetabular process is sharply pointed, and the dorsal margin of the
ilium is gently convex dorsally).  Lü's (2002) description was preliminary, and
the _Ingenia yanshini_ material will certainly be extremely relevant to a more
comprehensive description of _Heyuannia huangi_.>

  These appear to be autapomorphic; the relative shortening of the second and
third fingers is especially significant, and expansion of the sacrum beyond 6
sacrals within oviraptorids, suggests affinities next to *Ingenia;* whereas Lü
offers that these advanced sacral counts recall the condition of birds, he does
not offer that this is present only in advanced oviraptorids, not their
predecessors, which possess more "basal" counts of 6 (virtually all taxa _but_
*Ingenia,* *Heyuannia,* or *Nomingia* [see below]) or 5 (*Caudipteryx*).

<I thought _Nomingia_ only had five sacral vertebrae - putting it at the low end
of the oviraptorosaur range.>

  The authors suggest that *Nomingia* may have possessed up to 7 sacrals, and
that these vertebrae, which are not clearly defined from the dorsal series in
situ, may be either sacrals or dorsals. I am tentative in suggesting this as I
consider this evidence scanty at best: the elements appear unfused to the sacrum
as a whole, though Osmólska et al describe it as bearing 7 sacrals, largely as a
cohesive block between the alongated preacetabular alae of the ilium, which
should not be definitive; they also appear to lack ribs, which may be just as
distinctive.

  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)