acutigenia Russian Trilobite
Order Corynexochida, Superfamily Illaenoidea, Family Illaenidae
Time: Lower Ordovician, Asery Horizon
Site: Wolchow River Region, St Petersburg, Russia
Coming from the Middle Ordovician Asery Level deposits of the Wolchow
River region near Saint Petersburg, Russia, this is an example of
a rare trilobite of the genus Dysplanus. It is obviously related
to Illaenus, having a similar high profile of the cephalon, presumably
a feature that allowed it to plow the substrate looking for a meal.
One of the most obvious differences is that Dysplanus has NINE thoracic
segments rather than the TEN of Illaenus. Its dark caramel-colored
Calcite shell is well set off by the white limestone matrix, with
the trilobite preserved well centered. This is a taxon is only very
rarely seen. As always, the skillful Russian preparators have shown
this fine 3-D specimen to best advantage.