Re: Spinosaurs as what?

[Renato Santos <dracontes@hotmail.com>]

Demetrios Vital wrote:

> How plausible is this behavior considering the environs of
> Spinosaurus?  Are there other species of fish that congregate in
> shade, or other predators that use their shadow to hunt?

Well, I'm not all that knowledgeable about the paleoenvironment in that 
region of Africa (Baharija Fm.), except that it was an estuary. 
*Spinosaurus* has as far as we know piscivorous adaptations; I'm just 
proposing a modus operandi for the creature's feeding habits based on extant 
creatures that approximate its niche (if there are any). In fact, 
*Spinosaurus* might as well had brightly colored feet as some herons do to 
scare off fish as it waded ;-)
Being a big animal and presumably catching big fish in murky waters, I think 
this way of fishing provided two benefits: fish are naturally attracted to 
shades as they tend to denote thick vegetation and rocky areas where 
land-bound and aerial predators are less likely to attack them (at least 
that's what I hear on wildlife shows); the animal could use its shade as a 
way to diminish the glare the water's surface produces thus being able to 
see the fish more clearly.

> Really interesting speculation.  Is this even remotely provable?

If we had an generous amount of fossil evidence we could look at asymmetries 
in oxygen isotope ratios on the ribs or each side of the neurapophyses as 
these would be exposed to diferent temperatures and perhaps even 
histological evidence that shows how these temperature differences affected 
the bone. But this would only be valid if the animal used consistently the 
same side of the sail to produce shade. To prove that the animal waded 
regularly one could compare the oxygen isotope ratios on the feet and leg to 
the ones on for example the pubic bones, with obviously a calibration chart 
with results from extant waders, extinct waders and non-waders of each type.
I am perhaps going out on a limb here but it would be interesting if this 
could be done even on an academic standpoint.

Renato Santos

_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today it's FREE! 
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/