Isotelus gigas scale in cms CLASS - Trilobita ORDER - Ptychopariida FAMILY - Asaphidae GENUS/SPECIES - Isotelus gigas ROCK UNIT - Trenton Group AGE - Middle Ordovician (465 million years old) LOCALITY - Trenton Falls, New York, USA As the name indicates ("gigas" = giant), this was an unusually large trilobite species. This specimen measure over 24 cm (9.5 in) long. I. gigas fossils are common in the Trenton Limestones, but usually only as fragments. This specimen was oriented upside-down and flat in the limestone bed, and was nearly complete when removed from the outcrop (an unusual find). To learn more about Isotelus. PRI 2057C