Asaphus kowalewskii Russian Trilobite

with Enormous Eyestalks

Asaphus kowalewskii

Class Trilobita; Order Asaphida; Superfamily Asaphoidea; Family Asaphidae

Geological Time: Middle Ordovician, Asery Horizon

Size: 70 mm long by 52 mm wide

Fossil Site: Russian trilobites, Asery Horizon, Vilpovitsy Quarry, Wolchow River Region, Saint Petersburg, Russia

Asaphus kowalewskiiDescription: Coming from the Middle Ordovician Asery Level deposits of the Wolchow River region near Saint Petersburg, Russia, this is a large example of the trilobite Asaphus kowalewskii. Its caramel-colored Calcite shell is well set off by the white limestone matrix. Selective pressures from turbidity flows in the early middle Ordovician drove adaptation in some genera of Asaphidae leading to increasing eye stalk heights, for which Asaphus kowalewskii is the most striking example. The evolutionary innovation may have helped the trilobite better see and find prey, or see and avoid predators, or both. The evolutionary sequences from low to high set eyes are based on extensive cladistics data spanning some two million years of Ordovician strata from the region.

Also see: Russian Trilobites Gallery Russian Asaphidae Evolution Sequence

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