This is bizarre trilobite looks like something you might see in an Aliens movie. They first appeared in the fossil record in the Early Cambrian (521 million years ago) and went extinct during the Permian mass extinction (250 million years ago). Dicranurus is a genus of Lower to Middle Devonian odontopleurid trilobites that lived in a shallow sea that lay between Euramerica and Gondwana, corresponding to modern-day Oklahoma and New York, and Morocco, respectively. As such, their fossils are found in New York, Oklahoma, and Morocco. Size: 14cm by 11cm by 4cm # 20.