Kosmoceras

A pencil drawing of Schinderhannes bartelsi, an anomalocarid.

The curious thing is, the fossil of this species was found in Lower Devonian Hunsrück Slates, and to date the only anomalocarid to exist long after the Cambrian Explosion.

Ammonites and ammonoids are some of the most abundant cephalopod fossils that you can find in any strata before Cenozoic. Much of their biology is unknown, unlike its contemporary the belemnites. Paleontologists know, for sure, that belemnites possess ten arms with equal lengths, each arm lined with hooks; in life they would be fairly undistinguishable from common squids to casual observers. Ammonites however, are only known from the morphology of their shells. No unequivocal traces of its soft flesh have ever been found, thus it’s up to debate on how many arms they might have in life, or what kind of niche they might fill back in Mesozoic and late Paleozoic. To add to the confusion, some species are found with a set of calcareous plates, called aptychus, which have been speculated to function as operculum or even lower jaw, a component of its buccal mass.

One may point out that scientists have inferred much of their lifestyle from the ectocochleate, living Nautilus; however it’s important to remember that they are in fact, quite distant from nautiloids. Some research suggest that many lived in shallow water environments, and therefore it’s not out of possibility that they have advanced visual morphology just like modern coleoids do.

It’s such a pity that there are not a lot of solid paleontological reconstructions for ammonites out there.

Art by Olorotitan.

Edit: The artist tried to depict how an instance of ammonite cannibalism would look like. And obviously, this is not one of those weakly-conceived, half-hearted paleo-arts.