| A paleontology adventurer examines fossiliferous limestones in the late middle Ordovician Lehman Formation of the lower to middle Ordovician Pogonip Group, White Pine County, Nevada. Rocks along skyline also belong to the Lehman Formation, the youngest member of the Pogonip Group, which here produces prodigious quantities of large Leperdetia ostracods (a bivalve crustacean that is usually quite diminutive, ranging in average long dimension no greater than a millimeter, 3/64 of an inch)--in addition to locally common brachiopods and gastropods. |