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
|  Description:
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.
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