Aspidoceras perarmatus ammonite fossil collected from the Jurassic Oxford Clays of Oxford. Aspidoceras is an extinct genus of ammonite which can be found in Mid to Upper Jurassic sediments. They were nektonic carnivores which fell to the sea floor upon death. These examples were preserved within an oxygen starved deep marine shelf which gave rise to the Oxford Clay Formation. These specimens only measure 1.5 cm in diameter, the venter of the outer whorl is quite wide for their small size and some specimens exhibit feint ribbing. Supplied in small plastic bags with an information label.