Agnostid Trilobites Mass Mortality from Wheeler Formation

Description: Trilobites of Order Agnostida appeared in the early Cambrian, and were eye-witness to part of the so-called Cambrian Explosion; actually, since they had no eyes, they had to feel it. The Order went extinct toward the end of the Ordovician. Coming from the Cambrian Wheeler Formation deposits of Millard County Utah, this is a mass mortality plate containing some 17 complete specimens and many partials. Interestingly, a debate has long persisted whether Agnostids are trilobites, or a stem group to them. Another argument remain regarding whether they made their living in a benthic or palagic manner.