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Twenty Trilobite Fast Facts

  • Trilobites are extinct arthropods... distant relatives of modern lobsters, horseshoe crabs and spiders.
  • Trilobites existed for approximately 300 million years.
  • They lived from the Lower Cambrian Period (521 million years ago) to the end of the Permian (240 million years ago.)
  • Their emergence and extinction bookend the Paleozoic Age.
  • Trilobites are named not for their head (cephalon), thorax and pygidium, but rather for the three axial lobes that divide their body length-wise.
  • Their fossilized remains have been found on every continent on earth.
  • Trilobites ranged in size from 1cm to over 70 cm.
  • There are over 20,000 scientifically recognized trilobite species.
  • There are 10 "Orders" of trilobites, under which the more than 20,000 recognized species are organized.
  • The earliest trilobites were of the order Redlichia... the most recent were of the order Proedita.
  • In life, trilobites were covered by a thick chitinous exoskeleton which was molted as they grew.
  • Many trilobite fossils represent remnants of their shed exoskeletons, rather than of the trilobites themselves.
  • Some trilobite species have been found with long spines projecting from their shell... believed to have served as protection from predators.
  • Trilobites were probably the first life forms with complex eyes, with some species having hundreds of individual lenses per eye.
  • Some trilobites could enroll for protection.
  • Some trilobite fossils show evidence of soft appendages used for feeding and locomotion.
  • Famous "soft-bodied" trilobite localities include The Burgess Shale in British Columbia, The Emu Bay Shale in South Australia and The Chengjaing Formation in China.
  • It is believed that while trilobites lived mostly in off-shore marine environments, some may also have existed in fresh water.
  • Some trilobite fossils show signs of predation.
  • Collecting trilobites has a long history... some have been found in human burial mounds dating back more than 50,000 years.

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