These Ammonite Fossils are as beautiful as they are rare. Ammonite pricing is not only based on size and quality, but also on availability and is therefore subject to changes solely dependant on market values. Most people don't realize that Ammonite (Mesozoic cephalopod), is a close relative to the squid. These ammonite fossils first appeared in the Devonian, and went extinct with the Dinosaurs toward the end of the Cretaceous Period (65 million years ago). Click on the links below and own your very own ammonite fossil evidence for evolution.