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RE: SVPCA 50, REPORT IV




-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
longrich@alumni.princeton.edu
Sent: Friday, September 27, 2002 8:39 AM
To: dinosaur@usc.edu
Subject: Re: SVPCA 50, REPORT IV


On Thursday, September 26, 2002, at 03:27 AM, darren.naish@port.ac.uk
wrote:

> Hopefully this'll be the last email from on SVPCA.
> THEROPODS
>
> Paul Barrett showed that Norell et al's recent claim of filter-
> feeding and the presence of laminae in ornithomimids was,
> err, somewhat questionable (which makes you wonder how
> this paper got into _Nature_). In fact the pillar-like vertical
> structures seen on the median surface of the ornithomimid
> rostrum are pretty much identical to the same structures
> seen in sea turtles and ornithischians and are more to do
> with the presence of rhamphothecae than anything else
> (Nick Longrich and I were already onto this.. Paul has
> beaten us to it). Paul also investigated the energetics of
> filter-feeding and showed that it would not have been
> ecologically possible for ornithomimids to survive this way,
> even given a variety of postulated metabolic regimes. More
> likely (rediscovery of GSP 1988), ornithomimids were
> herbivores.
        Aw, nuts. Yeah, I have some cool photos of vertical ridges in the
palate of green turtles (which eat a lot of sea grass if I recall).
Anyways for other reasons the filter feeding hypothesis doesn't work too
well. An obvious problem is that filter feeders tend to have large jaws,
since you need a lot of surface area to process for your prey. Examples
include whales, basking sharks, megamouth sharks, anchovies, ducks,
flamingoes, and Pterodaustro.>>
But they sited Meger (sic, I don't know how to spell it) ducks that do not
have a large lower jaw.
 >>Ornithomimids, in contrast, are real
pinheads, such that it would be very difficult to process enough water
to feed them, I suspect.  Another is foot proportions. Wading birds like
ibises, herons, cranes, and flamingos have long toes to keep them from
sinking in the mud. Ornithomimids have among the smallest toes among
theropods, suggesting that they were instead highly terrestrial and
cursorial, like ostriches and ungulates.<<
Well, can't argue against that.
 >>Finally there are the forelimbs
which have been aptly compared to sloths by Osborn, the long straight
humerus, proportions of the manual digits, isodactyly, shapes of the
claws all look like them. The knuckles and opposable first digit don't,
but they do look like the knuckles of humans and other primates. If
these are designed for grasping branches, its hard to figure what could
be going on except that they are hooking branches to get at the leaves.<<
What about using the claws like in Friday the 13th movies. Wait, wrong move,
Nightmare on elm street (or whatever it was called). You know, stab the
little fur ball and swallow. Or wait, they used them like Edward Scissor
hands! They pruned the trees and ate the rest! THAT'S IT!!!  :)

Tracy L. Ford
P. O. Box 1171
Poway Ca  92074