Phil said:I still wonder if a rapid growth rate to attain a large size would be an evolutionary response to predation?...In other words, did these large ammonites have a faster growth rate in order to achieve a size free from predation, or did they grow at a similar rate to their smaller cousins?
Clem said:... does anyone have an idea of what likely constituted an ammonite's diet?
Phil said:Until someone can examine the stomach contents of a fossil ammonite no-one will know for sure.
The belemnite was probably a different case entirely. I'm sure those occupied a similar niche to the squids, fast moving and deadly.