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RE: Oviraptorids as Parrots?



John Scanlon (riversleigh@outbackatisa.com.au) wrote:

<you're mistaken about tiger shark morphology (or confused by vernacular
taxonomy; look up Galeocerdo cuvieri); they're broad, laterally hooked and
multi-cusped sawteeth and, as was pointed out earlier, the cutting force of the
bite is provided by lateral head-shaking rather than jaw adduction.  The teeth
are similar in Cretaceous Hexanchidae except that there's a row of biggish
cusps graded in size, while one cusp dominates in Galeocerdo.>

  I appreciate Scanlon's corrections on this matter. My referrences to the
shape (semi-conical, carinate, and slender) are in direct referrence to the
form of teeth in within lamnoid sharks, from *Isurus* to *Carcharodon*,
trending from extremely narrow recurved cones to broad, bladed, thick deltoid
structures. *Galeocerdo* (which, before anyone corrects me, I know to be a
carcharhiniform, and not a lamniform, shark) appears to be intermediate in such
a cline.

  However, I do admit I was confused on the degree of flexion of the primary
cusp, though all other cusps are so much smaller as to imply they are
essentially "enlarged denticles", and thus advocated a more puncture-perfect
model based on gross tooth morphology.

  Cheers,

Jaime A. Headden

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

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