PHACOPS--FOSSIL TRILOBITE, DEVONIAN PERIOD, with LARGE, EFFICIENT COMPOUND EYES 照片檔

PHACOPS--FOSSIL TRILOBITE, DEVONIAN PERIOD with LARGE, EFFICIENT COMPOUND EYES. Phacops is a widespread fossil in North America. This fossil was found in a Limestone Quarry in Illinois. The COMPOUND EYES (showing many facets) are crescent-shaped and unique, and allowed phacops to see 360 degrees. The larger expanded area between the eyes is the Glabella and has numerous granulations on the surface. Trilobites are extinct marine arthropods with three distinctive longitudinal body lobes. They are found worldwide with thousands of species. They first appeared in the Early Cambrian period of geological time (521 million years ago), and were abundant for millions of years, and became extinct during the Permian Mass Extinction (about 250 million years ago). Trilobites had a HARD EXOSKELETON which they shed several times as they grew in size--this left behind many fossils.