Megistaspis & Asaphellus Trilobites With Pos/Neg - Fezouata Formation
This is a pair of Ordovician trilobites Megistaspis (Ekeraspis) and Asaphellus from the Fezouata Formation of Morocco. One is 1.6" long and there is a second 2" long specimen lying underneath it. This specimen comes with both the positive and negative impressions.
Trilobites were a very diverse group of extinct marine arthropods. 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). They were one of the most successful of the early animals on our planet with over 25k described species, filling nearly every evolutionary niche. Due in large part to a hard exoskeleton (shell), they left a excellent fossil record.