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Re: marine reptile McMenu




Hello,

The size & degree of utilisation of the filter feeding niche is really
interesting to here about.

Tim, does the molecular evidence suggest that lower taxonomic levels of
Krill strated radiating at this time?

Molecular analysis aside, arn't there some pretty good reasons to suspect
that global ecosystem structures were quite different during the Mesozoic?

Off the top of my head (I'm sure there are quite a few others):
- Changes in global productivity, sea levels and climate
- Different sets of founding organisms after period triggering extinction
events (and their adaptations/exaptations)
- Different metabolic requirements of predators may have been different (eg.
leading to more trophic levels?)
- Changes in ecosystem level evolutionary process driven by keystone species
(eg. something like what we see in increasingly shorter genus life spans
among plants).

So, does anyone know of any study looking at overall changes in feeding
apparatuses among marine predators throughout the Mesozoic? If there are any
recognisable trends it would be quite interesting.

S!

-Jonas Weselake-George


----- Original Message ----- From: "Tim Williams" <twilliams_alpha@hotmail.com>
To: <danvarner@aol.com>; <dinosaur@usc.edu>; <twilliams_alpha@hotmail.com>
Sent: Thursday, February 28, 2008 8:58 PM
Subject: RE: marine reptile McMenu




Dan Varner wrote:

It has been suggested that the unusual South American plesiosaur,
Aristonectes, was a filter feeder.

See: http://www.plesiosauria.com/aristonectes.html


Thanks Dan.  If _Aristonectes_ used its small teeth and wide jaws to
strain out small prey, then I guess it qualifies as a filter-feeder.  A
similar life-style has been proposed for the New Zealand plesiosaur
_Kaiwhekea_ by Martin and Fernandez (2007; Geol. J. 42: 203–211); although
the original authors suggest that the jaws and teeth of _Kaiwakhea_ seem
better adapted for handling more substantial prey (Cruickshank and
Fordyce, 2002; Palaeontol. 45: 557-575).

Maybe certain Cretaceous filter-feeders were specialized for feeding on
krill.  Molecular analyses have suggested that krill (Euphausiidae)
appeared some time during the Cretaceous period (Jarman, 2001; Biol. J.
Linn. Soc. 73: 199-212).



Cheers

Tim
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