Asaphus raniceps Russian Trilobite

Description: This specimen is member of the Asaphidae, 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. Coming from an inland sea during the lower to middle Ordovician, the Russian trilobites from near Saint Petersburg, Russia participated in the Great Ordovician Radiation, which saw marine animal diversity increase three-fold more than the Cambrian Explosion. The Russian asaphid trilobites are a particularly interesting example of descent with modification. Asaphus raniceps was a stem trilobite that ultimately led to Asapahus ornatus, the last survivor of the genus.

Also see: Russian trilobites