Asaphus intermedius Russian Trilobite

Coming from the Middle Ordovician Asery Level deposits of the Wolchow River region near Saint Petersburg, Russia, this is an example of the trilobite Asaphus intermedius. The trilobite itself is 2.6 inches long (measured in straight projection) and 1.6 inches wide at the widest extent of the cephalon. There are two cystoids of the genus Echinosphaerites 1.5 and 1.3 inches across present as well. Its caramel-colored Calcite shell is well set off by the white limestone matrix and gray shells of the cystoids. The genus Asaphus underwent some remarkable adaptations to changes in turbidity during the Ordovician, with this one presumably arising in a time of increased turbidity (its eyestalks are intermediate between those of Asaphus kotlukovi and Asaphus punctatus).

Also see: Russian Trilobites Gallery Russian Asaphidae Evolution Sequence