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RE: Oviraptorids as Parrots?



Jaime, 
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. 
Cheers,
John
 
-----------------------------------------------
Dr John D. Scanlon
Palaeontologist, 
Riversleigh Fossils Centre, Outback at Isa
19 Marian Street / PO Box 1094
Mount Isa  QLD  4825
AUSTRALIA
Ph:   07 4749 1555
Fax: 07 4743 6296
Email: riversleigh@outbackatisa.com.au
 

-----Original Message-----
From: Jaime A. Headden [mailto:qilongia@yahoo.com] 
Sent: Sunday, February 05, 2006 11:13 PM
To: dinosaur@usc.edu
Cc: dannj@alphalink.com.au
Subject: Re: Oviraptorids as Parrots?

Dann Pigdon (dannj@alphalink.com.au) wrote:

<When you can bite through the shell of a marine turtle, there are few
food
resources that are beyond you... :)>

  However, most marine turtles are of the "soft-shell" variety, without
the
extensive plate-shaped bones as in land turtles. This makes getting
through a
marine turtle's shell rather easier than, say, a box turtle's or a
tortoise's.
Furthermore, while jaguars may make good analogies, also consider that
jaguars
are adapted for killing by biting into the skulls of their prey, and
thus would
necessarily be preadapted to biting through turtleshells.

  Tiger sharks, on the other hand, are much less selective in their prey
and
this have driven the lack of an adaptive dietary feature of the teeth,
and thus
their teeth are slender, carinate, and semi-conical, capable of
slashing,
piercing, and griping without much problems. Other sharks such as blue
and
great white (pointer) sharks are adapted to taking long massive chucks
out at
once, and their teeth are deisgned to go for prey much larger than the
gape of
their jaws. They don't try to gulp prey, like most hammerheads do, in
one bite,
but by shearing chunk after chunk.

  Cheers,

Jaime A. Headden

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

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