Detailed Fossil Ammonite Display. Jurassic Period, Toarcian, circa 184.2-174.7 million years B.P. An impressive freestanding structure containing scallop and belemnite fossils, as well as Hammatoceras and Grammoceras sp. ammonites showing strong ribbing, the largest specimen measuring 23 cm in diameter. 50.1 kg, 64.5 cm (25 3/8 in.). [No Reserve] with Science & Natural History, South Kensington, 27 April 2017, no.27.