Nankinolithus and Cyclopyge Moroccan Trilobites Association

Description: Well-preserved examples of members of the Order Asaphida of diverse morphology. The larger is Nankinolithus. The cephalic pits (fenestrae) are evident, the means by which this trilobite filtered detritus from the seafloor. The trilobite presumably hovered at the seafloor, using its legs to kick up particulates which then passed through the cephalic ring. It is found in association with a Cyclopyge preserved in dorsal aspect. This trilobite is thought to have been mesopelagic, meaning that it lived in the depths of some 200 meters. They slowly moved along filtering plankton. They lived in the dim twilight zone, and so needed large eyes to gather in light. Studies have shown their eyes to be similar to those of modern insects and crustaceans that live in dim light. The left side in the photo of both halves shows the positive of the Nankinolithus, the negative of the complete Cyclopyge, while the other half is reversed.