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Re: Shark eating dino fossil found in Utah
Good suggestion - potentially important if the fish were getting too
large to be swallowed whole. I imagine that a ~1m semiootid could be a
bit of a mouthfull for a Dilophosaurus sized animal? Processing food
via hands and arms would free the skull from the need to handle food
processing forces, potentially allowing the skull to be optimised for
prey capture. Or perhaps the forelimbs could play a role in that as
well (c.f. the bear and salmon analogy).
Does anyone know how big the armoured catfishes in S. America get. And
do caiman ever eat them? Might give you some clues.
I wonder if being a biped actually helped in this case. The theropod
in question could have grabbed the fish with its procumbent front
teeth, in the same manner as rhamphorhynchids and many sauropterygians
and crocodyliforms. Once caught, the theropod could then use its
hands to help prise off the armored skin so the fish could be easily
dealt with by the jaws.
Dann Pigdon wrote:
"The only other meat-eating dinosaurs with teeth worn like that are
the spinosaurs Spinosaurus and Suchimimus from North Africa where
large...fish dominated," said Kirkland.
I wonder if the teeth of *Masiakasaurus* show a similar wear pattern?
The papers that have dealt with _Masiakosaurus_ (Sampson et al., 2001;
Carrano et al., 2002) do seem open to the idea that _Masiakasaurus_
was piscivorous. The procumbent front teeth could have been used to
clasp fish, and the more typically theropod recurved teeth behind
could process the prey. Based on the dentition, these studies also
raise other possibilities for _Masiakasaurus_'s dietary habits - such
as eating fruit or small prey (like insects), or both.
Piscivory has been proposed for spinosaurs, based on the
crocodilian-like morphology of the jaws (although Sues et al. 
disagree) and the discovery of partially digested fish scales inside
the _Baryonyx_ skeleton (Charig and Milner (1986, 1997). However, the
same skeleton also has partially digested bones of a small ornithopod
(not sure if it would still be categorized as _Iguanodon_), and
spinosaurs are known to have fed on pterosaurs (Buffetaut et al.,
2004). Spinosaurs obviously had diverse diets, and the same is
probably true of other fish-eating theropods. Just how dedicated thet
were to piscivory is unclear; but then there's this intriguing idea...
Basal oviraptorosaurs (_Caudipteryx_, _Protarchaeopteryx_,
_Incisivosaurus_) also have procumbent teeth. These critters might
have included arthropod prey in their diet. One idea of mine
(completely untestable, and so not worth a jot) is that these
theropods used their wings and feathered tails to flush insects out of
small trees into the open, like some birds do today (wagtails, etc).
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