Re: Regarding Spinosaurus

["Steve Brusatte" <dinoland@lycos.com>]

On Mon, 7 Jan 2002 16:47:03   
 Graydon wrote:
>On Mon, Jan 07, 2002 at 03:23:51PM -0600, Williams, Tim scripsit:
>> Graydon wrote:
>> >Has anyone considered the possibility of the jaw structure being
>> >intended, not particularly for pscivory, but for feeding from the body
>> >cavities of sauropods?
>> 
>> You mean like vultures? 
>
>Not particularly like vultures; I'm thinking that they were active
>predators, but that they might have had an odd mode of feeding.  The
>contents of the body cavity tend to the highest food value of any part
>of the prey animal, and there's problems with using _all_ of a carcass;
>it might make sense to specialize in getting the most nutritional value
>from the kill before abandoning it, in preference to defending it.
>(Since that usually isn't actually worth the effort, once you're full.)

Interesting idea.  I wish Marco Mendez was still onlist, as I'm sure he would 
have something to say.  I'll have to e-mail him later.  Anyway, I like this 
idea.  Boy, it would sure throw a kink into Horner's hypotheses (wouldn't it be 
funny if his big, mean JPIII Spinosaurus turned out to be a scavenger and 
Tyrannosaurus a predator? :-))

>> Spinosaurs have a strong manual claw that might have been useful in
>> tearing open carcasses.  Spinosaurs would also need a flexible neck -
>> and, judging from the cervical articulations, this appears to be the
>> case.  If I've interpreted Graydon's post correctly, the spinosaurs
>> could use their slender heads for probing through the rib cage of big,
>> dead herbivores - perhaps picking out the leftovers left behind by
>> stronger, more predaceous theropods.  A real nice idea.*  It might
>> also explain the posteriorly-migrated nares - it can be pretty icky
>> nosing around deep inside carcasses.
>
>It does all seem to fit; anyone got a suggestion as to how one could
>test it?

Well, it would be a tough hypothesis to test.  But, comparing spinosaurids to 
extant scavengers that feed on large bodied carcasses would be a start 
(especially looking at the position of the nares, the size and serrations of 
the teeth, the size, width, and strength of the jaws, etc.).  The problem here 
is that I know of know large-bodied scavengers, which spinosaurids most 
definitely were.  

>> *I should add that _Baryonyx_ has been found with fish remains in its
>> stomach, hence the currency of the fish-eating spinosaur idea.  However,
>> this only tells us what the individual's last meal was, not what the diet
>> was for the entire species.
>
>I can see them eating fish just fine, too; I doubt any theropod has ever
>been what one would call a picky eater.  I do have some trouble
>imagining a multi-ton terrestrial facultive fisheater, though.

Yep, it's tough to imagine an animal that large feeding only on fish, although 
some of the fish it lived near were quite large.  It's also hard to imagine an 
animal of that size being a scavenger, but Graydon's hypothesis makes sense.  
If spinosaurids could take down a large quarry (which they most likely could!), 
then their snout and claw adaptations could be used to extract the most 
succulent and nutritious meat.  Spinosaurids most likely occupied an 
untraditional niche, be it fish-eating, scavenging, pure "hunting," or a 
combination of all three!

Steve

---
***************************************************************
Steve Brusatte-DINO LAND PALEONTOLOGY
SITE: http://www.geocities.com/stegob
ONLINE CLUB: http://clubs.yahoo.com/clubs/thedinolanddinosaurdigsite
WEBRING: http://www.geocities.com/stegob/dlwr.html
INTERNATIONAL LANGUAGE SITE: http://www.geocities.com/stegob/international.html
****************************************************************