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RE: Oviraptorosaur tail forms and functions

Distal fusion of caudal vertebrae also occurs in *Shunosaurus lii*; *Omeisaurus 
tianfuensis*; a club was referred to *Mamenchisaurus hochuanensis*, but differs 
in gross morphology (tall and narrow as opposed to broad and "inflated") among 
nonavian dinosaurs. There is also the tail ... thingy ... in megalancosaurids, 
which is triangular, huge and hook-like. A pathological tail in 
*Pachyrhinosaurus* sp. resembles the *Mamenchisaurus* "club," and may suggest 
it is also pathological (Tanke and Rotschild, in _New Perspectives on Horned 
Dinosaurs_), and several other groups of lumped caudals in ceratopsids are 
known (which also exhibit fairly short tails).


  Jaime A. Headden
  The Bite Stuff (site v2)

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 

> Date: Thu, 10 Jan 2013 05:53:01 +0000
> From: keenir@hotmail.com
> To: tijawi@gmail.com; dinosaur@usc.edu
> Subject: RE: Oviraptorosaur tail forms and functions
> > Date: Thu, 10 Jan 2013 15:55:24 +1100
> > From: tijawi@gmail.com
> > To: dinosaur@usc.edu
> > Subject: Re: Oviraptorosaur tail forms and functions
> >
> > Michael Habib <biologyinmotion@gmail.com> wrote:
> >
> > > I see what you're getting at, but do we really have a good threshold for
> > > being "over-engineered"? Why can't a muscular, mobile tail basically just
> > > be a display structure?
> >
> > It may well be just be a display structure. I hope it is the case
> > that large oviraptorosaurs sported large and elaborate "fans". My
> > argument (such as it is) is that the evidence is not compelling - at
> > least as far as derived oviraptorosaurs are concerned. Across
> > non-ornithuromorph theropods, there is no correlation between the
> > presence of a pygostyle and a tail "fan" (= a radial arrangement of
> > feathers).
> I would think that oviraptorosaurs wouldn't need a large fan-tail...as their 
> heads already make an ideal display structure. (On the other hand, having the 
> head and a fan-tail both being display structures, might provide the same 
> sort of advantage that eyespots and false heads serve in fish and reptiles)
> > Many non-ornithuromorph birds (confuciusornithids, several
> > enantiornitheans) have a pygostyle, but no tail fan - although they do
> > show terminal feathers (often streamer-like) that appear to have been
> > used for display, associated with the pygostyle.
> Perhaps additional comparisons are needed? You mentioned three groups within 
> the Therapoda who have a pygostyle - does the feature appear outside the 
> Theropoda?
> (from what I remember last I saw a specimen in a museum, ankylosaurs have a 
> similar-looking structure in their own tails; yes/no?)