Via Brian Switek's site:
... Exactly what species produced the coprolites is unknown, but after analyzing a third specimen of the same composition found nearby the scientists determined that it had been produced by a carnivorous vertebrate other than a shark. A crocodile seemed to be a likely candidate, but the thing that made the paleontologists undertake this analysis in the first place was that the fossil feces showed characteristic tooth marks; one of the coprolites had been bitten into and the other had been severed. (You don't often see lines like "This tooth penetrated the feces to a depth of about 3 mm." in the literature.) A shark had bitten into these feces, but what kind of shark, and why?...
