Asaphus lepidurus Lower Ordovician Russian trilobite

Description: A large, well-inflated example of an ancient member of the Asaphidae, this is Asaphus raniceps. The region in which these trilobites lived was subject to dramatic changes in salinity and turbidity, and the trilobites were able to make rapid (geologically speaking) evolutionary adjustments. These adjustments were thought to be able to allow them to see both predator and prey more easily. This taxon was a stem trilobite that ultimately led to Asapahus ornatus, the last survivor of the genus.