Guts-Eating Spinosaurs

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

Hey,
Here is a reply from Marco Mendez (who is currently off-list) regarding the 
ongoing "spinosaurids as specialized innards-eaters thread":

"About spinosaur feeding, well that is a problem, due to the fact they
are fragmentary and enigmatic. However, we can still discern some things
just from the bones we have. I do believe that spinosaurs ate other dinosaurs
along with fish. Modern crocodiles do this sort of stuff, except they
eat other crocs, mammals, and fish (Sarco is the one who ate dinos).
 

I do not completely object to spinosaurs being able to stick their mouths
into sauropod bellies or what not, however, they have to take down this
animal as well. (there might be another explanation, I'll get to this
a bit later). Spinosaur skulls and necks are not very strong to take
down a big animal. Their skulls are long and narrow, with no much width
they really cannot clamp down on such prey. Spinosaurine teeth have no
serrations in them, and they are straight, kind of like gharial teeth
or crocodile teeth. Baryonichid (suchomimus and baryonyx) teeth have
serrations, but not curved back toward the throat. There is some curvature,
however it is not so great that it woulc convince me. Both spinosaur
types seem not to have very strong teeth, as seen in T. rex or the other
gigantic predators. 

Tooth comparison:  
If you were to take a tooth of _Suchomimus_ and that of _Carcharodontosaurus_
and compare them, you'd see some obvious differences. While the Carch.
tooth is narrow, it is curved back and has  big serrations. While the
Sucho. tooth has serrations, it lacks the knife-like serrations of Carch.
More oval-ish, the Sucho. tooth  is smaller. Now in the jaws, the teeth
are curved back in Carch. to hold in prey. In spinosaurs the teeth are
much more numerous and not so curved. 

About the other theory, they may have poked around, however they were
scavangers. Not very likely, since they are animals that lived near the
river shores and tended to eat fish. In the belly of Baryonyx, some fish
cales along with acid-etched bone has been found, suggesting spinosaurs
ate fish and dinosaur meat. I do not doubt other spinosaurs ate meat
along with fish. The claws are most widely though to be used while fishing,
since they do have to drag out 300pds+  of fish out of the water. In
Spinosaurus' time there was a huge meat eater who had the dinosaurs,
Carcharodontosaurus. I think he would be the main predator in land, followed
maybe by Spinosaurus, until other fossil material arises. 

I cant say the sail helped in hunting, however it migth have helped to
intimidate other dinosaurs. 

As for eating inside tummies, well I dont know, spinosaurs could have
done this, just not as a long term habit. A long snout would be more
useful to catch slippery prey, I would argue that a short snout be more
useful in poking into stomach crevises, since it allows for more grab
than a spino skull (I dont know much about this argument, I am just putting
this out there).

-marco"

Regards,
Steve

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Steve Brusatte-DINO LAND PALEONTOLOGY
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