Several lines of evidence along with a new 3-D model of the way the mouth parts of Anomalocaris worked show that the infamous carnivore could not crack the hard shells of trilobites and other protected critters of the Cambrian seas.
"The mouth parts appear soft and bendable in (fossil) specimens," said paleontologist James "Whitey" Hagadorn of the Denver Museum of Nature & Science. "That struck me as kind of funny."
Soft mouth parts don't jive with the now standard interpretation of Anomalocaris being a predator that wolfed down trilobites and anything else it could catch. That got Hagadorn wondering: "Is it possible that Anomalocaris didn't eat trilobites?" he asked.
To find out, Hagadorn started looking at all the available fossilized feces from the Cambrian time when Anomalocaris lived. None containing mangled bits of the hard, indigestible exoskeletons of trilobites could be found that could be traced to Anomalocaris.
What's more, there is no evidence of trilobite parts in the gullets of any known Anomalocaris fossil.
For that matter, no gut contents have ever been found for any of the dozen or so known species of Anomalocaris, he said. That's especially strange considering that hundreds of other fossil animals found nearby have guts filled with all sorts of interesting stuff.
To get a better idea just what Anomalocaris might be capable of eating, Hagadorn and his colleagues devised a 3-D, finite element analysis model of the Anomalocaris's whorl of mouth parts. The model let them virtually operate the mouth to see what it could do and how much force it could generate.
The answer is that Anomalocaris couldn't close its mouth and could not create forces strong enough to break a modern lobster or shrimp shell -- the analogues they used for trilobite shells.
Read more at Discovery News
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