Species Name: Arnioceras Semicostatum
Age: Jurassic, Lower Lias, approximately 180 Mya
Location: Holderness Coast, East Yorkshire, UK
Arnioceras Semicostatum remains within limestone matrix from the Lower Jurassic rocks of the Holderness Coast, East Yorkshire, UK. Arnioceras is an extinct genus of ammonite which existed during the lower Jurassic period. These specimens were found within the Lower Lias rocks of Holderness, Their shell is evolute and they bear pronounced, sharp ribs with a ventral keel without furrows. These particular specimens are supplied in 3" x 2", 4" x 3" and 5" x 3.5" white card trays depending on the size of the limestone block in which the fragmented ammonites are contained.