Cupulocrinus sp.   scale in cms CLASS - Crinoidea ORDER - Cladida FAMILY - Cupulocrinidae GENUS/SPECIES - Cupulocrinus sp. ROCK UNIT - Richmond Group AGE - Upper Ordovician (445 million years old) LOCALITY - Cincinnati, Ohio, USA These tiny (note centimeter scale, above) crinoid crowns (cups with arms) represent one of the largest groups of crinoids found in Paleozoic rocks - the inadunates. However, only one genus of this group of crinoids survived the great End-Paleozoic extinction event. PRI 42102