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Re: A Whole Bunch Of Questions



Ivan Kwan (dino_rampage@hotmail.com) wrote:

<2) Is Tarascosaurus salluvicus considered an abelisaur?>

  Though it is certainly a ceratosaur based on the proximal femoral
anatomy, thew mis-named [see note] *Tarascosaurus* has distinct dorsal
vetrebrae that are, upon inspection, still closer to abelisaurids than
they are to ceratosaurs in general, which are "plesiomorphic". Abelisaurid
posterior dorsals have a distinctive centrodiapophyseal lamina "wing-like"
arrangement of the diapophysis and parapophysis which persist into the
sacral series, maintaining double rib heads to the very last dorsal and
into the sacral series (thought the heads have merged with the apophyses
of the centrum and there is no longer an apse between them). Other than
that, the animal is largely defined by its location, the first
"abelisaurid-type" from France. 

  Note: the name *Tarascosaurus* derives from the French armored monster
called the Tarasque, notably quite spiky, on the basis of the assumption
that abelisaurids were armored and that local *Ampelosaurus* scutes were,
in fact, pertaining to the theropod. The tarasque in French art is usually
characterized as a predatory dragon with a larger armored carapace
resembling the snapping turtle, only more metallic.

  This response answers the already and previously answered question 3:

<3) Among the 3 Late Cretaceous European sauropods, Ampelosaurus,
Hypselosaurus & Magyarosaurus, which are known to have possessed armour?>

  *Magyarosaurus* has been attributed some armor in the past, especially
as part of Nopsca's serious of papers on Transylvanian dinosaurs, but
these are generally now thought to belong solely to *Struthiosaurus*.
*Magyarosaurus* is a particularly dwarfed diplodocoid, and no diplodocoid
has been "known" to have body armor; though it's not _impossible_, its
unlikely *Magyarosaurus* was armored.

<5) How does Styracosaurus ovatus differ from S. albertensis?>

  Based on the types, "*S." ovatus* has only two long epoccipital spikes,
whereas *S. albertensis* has three. This is intermediate between the
pachyrhinosaurs (including *Einiosaurus*) and *Styracosaurus* and Horner,
when originally looking at the series upon discovery of *Einiosaurus*, has
ascribed the *ovatus* form to an intermediate morphotype that is
diagnostic only by the absence of a single pair of epoccipital spikes.
Likely it is no more diagnostic than this, and that is a piddling reason
really to define any more unique a species name, or grant it a "genus"
name of its own.

  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)

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