Pliomera fisheri, an Unusual Russian Trilobite
with Attached Hypostome

Name: Pliomera fisheri Russian trilobites (Order Phacopida, Suborder Cheirurina)

Age: Middle Ordovician, Asery Horizon

Size: (25.4 mm = 1 inch): 40 mm long by 20 mm wide on a 94 by 63 mm matrix

Location: Wolchow River Region, St Petersburg, Russia

Pliomera fisheri Russian TrilobiteDescription: Coming from the Lower Ordovician Wolhovian Level deposits of the Wolchow River region near Saint Petersburg, Russia, this is an example of the rare trilobite Pliomera fisheri. It is a member of the Order Phacopida, Suborder Cheirurina. The most distinctive feature of this trilobite is the notched pygidium. These trilobites are nearly always found in an enrolled condition with the pygidium neatly tucked under the cephalon. Enrollment was a defensive posture assumed by most trilobites. This one took it one step further; the notches allowed the trilobite to breathe freely while enrolled, allowing it to wait out any would-be predator. This fine prone specimen is perched over the edge of its matrix to allow you to see the hypostome, or anchor for the mouthparts. It displays well on this matrix which has a flattened base for self-display.

click to enlarge

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