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Re: Sexual Dimorphism (was : Defunct genera and _Pekinosaurus galtoni_)



Rob Gay wrote:

<In ammonites, there is a solid case for sexual
dimorphism and I believe there is a pretty strong case
for it in _Coelophysis_ _bauri_, using neck vs. torso
length, limb ratios and skull lengths. Perhaps this
type of data could be applied to other closely related
theropods (which is actually work that I am in the
process of doing right now). But, unless there is a 
significant population sample to draw data from (like
the Ghost Ranch quarry), then speculation on
individual variation is just that, speculation.>

  Raath (1990, in the _Dinosaur Systematics_ volume)
has suggested that the *Syntarsus rhodesiensis*
assemblages represent a sexually dimorphic group, as
in *Coelophysis* (Colbert, 1990, same volume). Paul,
1988 (PDW) and subsequently has demonstrated and
described dimorphic populations in *Syntarsus*,
*Coelophysis*, *Tyrannosaurus* (also suggested by
Carpenter, (1990, see above) Larson (1995, 1997) and
others) *Triceratops* (Lehman, Forster, others) and so
on. Robusticity, placement of the first chevron, form
of the ischium, femur, prescence of "sexually related"
crests (Dodson, 1974) in hadrosaurs, and I think
Norman suggested *Iguanodon atherfieldensis* is a
feminine variation of *I. bernissartensis.* So this is
hardly an unexplored field. Smith and Chure have both
been looking at variation in *Allosaurus*, and popular
texts have suggested the cranial crests of some
theropods (*Ornitholestes*, *Oviraptor*,
*Proceratosaurus*) were sexually related. Oh well....

=====
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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