From the BBC:
Thursday, 25 November 2010
By Zoe Kleinman
BBC Reporter, Dorset
Zoologist Chris Andrew and geologist Paddy Howe in Lyme Regis say that one in four of the fossils bears the mark, which is visible to the naked eye.
Their research supports similar findings from experts in Belgium.
The pair, who wrote the paper, believe the ammonites were eaten by a fellow cephalopod such as a soft-bodied squid.
These creatures had beaks which they could have used to break the ammonite shells, said Paddy Howe.
“It’s got to be something that can grab the ammonite and manipulate it into the right position – certainly modern cephalopods are capable of this sort of behaviour,” he said.
“The modern Humboldt squid can be five or six feet (1.5 – 1.8m) in length, it can take chunks out of a wetsuit or a diver, so yes, it would be perfectly capable of biting through the relatively thin shell of an ammonite.”
Shell-dwelling ammonites, believed to be ancestors of modern cephalopods, became extinct towards the end of the Cretaceous period.
“Whatever killed the dinosaurs, it was probably the same factors,” said Mr Howe, who runs the Fossil Workshop in Lyme Regis along with Mr Andrew.
As for why the bite marks are so prevalent on the Jurassic Coast – it is simply a matter of numbers, said Paddy Howe.
“In any area where you have an abundant food source there are going to be predators there taking advantage of it.”
Who Are The Ancestors Of Modern Squid? Here.
Squid Ink Revisited: here.
Seasonal distribution of early life stages in squid of the Lazarev Sea, Antarctica: here.
Nautilus at Risk – Estimating Population Size and Demography of Nautilus pompilius: here.
Cuttlefish use visual cues to mimic their surroundings for maximum camouflage: here.
Cuttlefish Hatchlings: here.
Thousands of Squid Surround Photographer: here.
Squid Males “Bisexual”— Mating with anything with eight arms pays off in dim depths, study says: here.