Rare Asaphus delphinus Russian trilobites

This is a double of a rare trilobite from the Ordovician strata near St. Petersburg, Russian. Ocurring in the Middle Ordovician, Asaphus delphenus terminated an evolution line of Asaphus from the region that forked from Asaphus lepidurus in the Lower Ordovician. Delphinus, with its distict morphology, was preceeded in a linear progression by proginitors Asaphus species lamanskii, raniceps, and major. The smaller delphenus is folded with the Hypostome (the anchor for trilobite) mouthparts fully visible.

Also see: Russian Trilobites Gallery Russian Asaphidae Evolution Sequence