Re: Caudipteryx and the dark side

["Jaime A. Headden" <qilongia@yahoo.com>]

David Marjanovic wrote:

<Described as Nomingia gobiensis, though I forgot
where. (At times when National Geographic still wrote
it was unnamed, The Dinosauricon used Nomingis
brevicauda as its name, the s of which is easily
identified as a typo).>

  It isn't a typo; the name was the manuscript name
for the animal before it was finalized by Barsbold et
al., 2000b [in _Acta Paleontologia Polonica_
45(2):97-106], and was first mentioned here by Brush
[in the archives]. Mike listed the name as a
provisional reference, and that's all it was. I would
actually have preferred the manuscript specific name,
but oh, well...

<<show any changes in hindlimb dimensions relative to
species with "normal" length tails?>>
 
<I'd love to know too...>

  *Nomingia* has very long legs, and the femur easily
ascends to anterior the mid-point of the chest.
Oviraptorosaurs and therizinosauroids all have very
short thoracic regions, even though the vertebral
coundt is not significantly altered (there are eight
or ten dorsals in the holotype, the problem being the
cervicalization of the cranial dorsals) and this is
similar to *Alxasaurus*, and even more so to the known
material of *Beipiaosaurus* where the preserved
dorsals suggest a very short thoracic region.
Meanwhile, the tail is shorter than the presacral
column, composed of some 23-24 caudal vertebrae, the
last three or four of which are firmly appressed and
the distalmost two or three fused, forming the
aforementioned pygostyle. It is fundamentally similar
to *Caudipteryx*, but the Liaoning fossil does not
bear a pygostyle, and may also hold true for the
significantly similar *Alxasaurus* and oviraptoroid
caudal sequences, though as reported by Barsbold et
al., 2000a [in _Nature_] "Rinchenia" *mongoliensis* (=
*Oviraptor*), *Conchoraptor,* and *Ingenia* do not.
The caudal sequence in caenagnathids are not
sufficient to tell whether the condition was probable,
but it is possible.

  Additionally, the limbs are extraordinarily slender
for a non-avian maniraptoran, whereas the legs of
dromaeosaurs, therizinosaurs, and oviraptors tend to
be rather robust and short. The tail is almost as
short as the tibia, which probably says as much for
the tibia as for the tail, but the metatarsi are not
preserved, so it would be impossible to place
*Nomingia* in Gatesy's or Farlow's plots, even though
everything else is there. The normal formula for a
maniraptoran pes is about 120% or more the length of
the femur, shorter than the tibia (an unnanmed
oviraptorosaur preserves a functional hindlimb that,
using Gatesy and Middleton's plots, is roughly
30%-30%-30%, but that's the exception), so you can
postulate the metatrsus and digits off
comparable-limbed forms, like *Caudipteryx.*

=====
Jaime "James" A. Headden

  Dinosaurs are horrible, terrible creatures! Even the
  fluffy ones, the snuggle-up-at-night-with ones. You think
  they're fun and sweet, but watch out for that stray tail
  spike! Down, gaston, down, boy! No, not on top of Momma!

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