This Specimen has been sold.
2.8" Crotalocephalina & Paralejurus Trilobite Association
This is a natural association of two different Lower Devonian trilobites from Foum Zguid, Morocco. There is a Crotalocephalina gibbus which would be about 2.4" long if outstretched and a Paralejurus which is about 18" long. The limestone surrounding them has been removed and sculpted to create a nice presentation.
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.