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Re: What did Spinosaurus eat? New species of Lepidotes found

> 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.

True, but I was thinking about ducks. Doesn't their plumage trap air
for greater buoyancy? And can't the amount of trapped air be controlled
by fluffing or depressing the feathers? 

I was also thinking about "dino-fluff" versus tight, water repelling,
insulating feathers. (Although now that I think about it, fur seems to
work pretty well for otters -- and they don't even rely on a thick layer
of blubber for warmth.) Might the ability to float on the water surface
-- or, at least to avoid soaking and chilling -- be of use to otherwise
terrestrial or arboreal animals "contemplating" a more aquatic
lifestyle? (I'm imagining only small dinosaurs -- nothing the size of an
adult Spinosaurus.)

-- Donna Braginetz

> I imagine that non-avian theropods would have had similar problems
> where diving was concerned,
> 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 themselves.