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Re: What did Spinosaurus eat? New species of Lepidotes found
On Tue, Feb 22nd, 2011 at 1:43 PM, firstname.lastname@example.org wrote:
> Tim Williams wrote:
> > Is there something about birds that allowed them
> > to exploit aquatic niches in the Mesozoic?
> Development of water-resistant and/or air-trapping plumage?
For a diving bird, air-trapping plumage can be a distinct disadvantage. Some
diving birds, such as
cormorants, lack water-repelling oil on their feathers - specifically to allow
the feathers to become
water-logged to make the animal as heavy as possible while diving. The avian
body plan is already
extremely bouyant, even without trapped air beneath the feathers.
I imagine that non-avian theropods would have had similar problems where diving
with their avian-style respiratory systems. Perhaps large theropods were
prevented from becoming
habitual divers because of their inherant bouyancy.
Having giant crocs, pliosaurs and mosasaurs in the oceans and waterways
probably didn't help
much either. Large theropods would have had a hard time competing with them in
deep water -
especially if they were stuck bobbing like corks at the surface and making
appetising targets of
themselves. However spinosaurs probably had the 'mega-wader' niche largely to
Spatial Data Analyst Australian Dinosaurs
Melbourne, Australia http://home.alphalink.com.au/~dannj