Phacops rana scale in cms CLASS - Trilobita ORDER - Phacopida FAMILY - Phacopidae GENUS/SPECIES/SUBSPECIES - Phacops rana rana ROCK UNIT - Moscow Formation, Hamilton Group AGE - Middle Devonian (380 million years old) LOCALITY - Hamburg, New York, USA Phacops is one of the most common trilobites of the Devonian Period. Although several trilobites on this slab appear to be complete, the head or tail segments on most individuals are only slightly connected. This suggests that the specimens represent molts, shells that were shed during stages of growth. Take a closer look at Phacops. For more about molting see Asaphiscus. PRI 41461