Ammonoidea - Soft-part Anatomy

Soft-part Anatomy

Although ammonites do occur in exceptional lagerstatten such as the Solnhofen limestone, their soft part record is surprisingly bleak. Beyond a tentative ink sac and possible digestive organs, no soft parts are known at all. They likely bore a radula and beak, a marginal siphuncle, and ten arms. They operated by direct development with sexual reproduction, were carnivorous, and had a crop for food storage. They are unlikely to have dwelt in fresh or brackish water.