Oxynoticeras Streamlined Ammonite from UK

Description: This fine ammonite is the rarely-offered Oxycone known as Oxynoticeras oxynotum, and is a fine pyritized example. Oxycone ammonites had a compressed shell. The sharp keel and narrow cross-section offered little resistance as the ammonite moved through the water in pursuit of prey and in an effort to escape predators. This taxon is thought to have been one of the swiftest of ammonites. Notice the suture pattern which afforded the shell strength with little cost in weight, allowing the ammonites to move swiftly through the water column.