Jurassic Ammonite Psiloceras IF-JA-16-001Psiloceras (Caloceras) johnstoni Lower Jurassic (Hettangian) Doniford Bay, Watchet Sommerset, United Kingdom Here is a vivid example of beautiful ammonite iridescent shell from the UK. This ammonite is preserved in organic rich black Jurassic shale. These thin walled ammonites are crushed, as are most of the ammonites found in this locality. Flattening of the specimen has increased the area of iridescence of the shell, which is composed of alternating