Ptychagnostus Blind Trilobites of Cambrian Utah

Description: Coming from the Cambrian Marjum Formation deposits of Millard County Utah this is an example of a pair of the trilobite Ptychagnostus akanthodes. The members of the Agnostida are mostly thought to have been planktonic in nature. Most are blind, and have a pygidium equal in size to the cephalon (ispopygous), making it hard to tell which end was which! They are remarkably detailed for such tiny specimens, and fully articulated.