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Re: Questioning the Validity of Hypsirophus discurus



couldn't have said it better myself ;-)

>>> "Jaime A. Headden" <qilongia@yahoo.com> 01/15/04 22:16 PM >>>
Tommy Bradley (htomsirveaux@hotmail.com) wrote:

<I hope my frequent e-mails aren't bothering anyone, but, I have another 
question.  I know that some of the material of _Hypsirophus discurus_ is
now referred to _Allosaurus fragilis_, and that some other species of 
_Hypsirophus_ have been  made synonyms with species of _Stegosaurus_. 
Well, is _Hypsirophus discurus_ completely synonymied with _Stegosaurus_? 
Or is the meager material (2 dorsal vertebrae, caudal neural arch
fragment) still retained under the name _Hypsirophus_?

  The simple version of this question would be thus: _Hypsirophus_ = 
_Stegosaurus_ right?

  And if _Hypsirophus is still retained, then can anybody clue me into the
meaning of the species name, _discurus?  I know there is a Parrot with the
 same species name, and I think it means "Racquet-tail" but I would 
appreciate some confirmation.>

  To potentially interrupt Ken Carpenter on this subject, I will find a
way to answer these questions.

  1) Historically, *Hypsirophus* was included in *Stegosaurus;* a portion
of the holotype, the neural arch fragment, was referred to *Allosaurus,*
making the hypodigm of *H. discurus* polyphyletic.

  2) No, apparently *Hypsirophus* may be valid on it's own. Carpenter
(1998) and (2001) contend the taxon is distinguishable from *Stegosaurus*
specifically. Geologically, it occurs in the uppermost Morrison, whereas
*Stegosaurus* is restricted to the middle, and *Hesperosaurus* to the
lowermost.

  3) _discurus_ means "disk tail" in Greek, and is a reference to the
disk-shaped centra of the dorsal vertebrae, wich Cope (1878) beleived
belonged to the caudal region.

  Carpenter, K. 1998. Vertebrate biostratigraphy of the Morrison Formation
    near Cañon City, Colorado. (in Carpenter, Chure & Kirkland, eds., _The
    Morrison Formation: An Interdisciplinary Study_). _Modern Geology_ 23:
    407-426.
  Carpenter, K.; Miles, C.A.; and Cloward, K. 2001. New primitive
stegosaur
    from the Morrison Formation, Wyoming; pp. 55-75 in Carpenter (ed.)
_The
    Armored Dinosaurs_ (Indiana University Press, Bloomington &
    Indianapolis).
  Cope, E.D. 1878. A new opisthocoelus dinosaur. _American Naturalist_ 12:
    406.

=====
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)

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