Animal Armageddon
Trilobites
Scavengers of the Sea: Trilobites were scavengers of the Paleozoic oceans. Being industrious creatures, they kept the sea floor clean, gobbling up almost anything they could find: dead plankton, bits of algae, even animal waste. These hard-shelled creatures had multiple body segments with jointed legs, compound eyes and breathed through their gills. Isotelus rex, pictured above, was the largest known trilobite species at over 2 feet in length. The smallest trilobite species were about a quarter of an inch long.
The Ubiquitous Trilobite: Trilobites are among the most common creatures found in the fossil record. They first appeared in the Cambrian, some 540 million years ago, and lasted some 300 million years until they were all but wiped out during the Permian-Triassic extinction event. To date, over 17,000 species have been described. They are the earliest known animals to possess vision, the most advanced species possessing compound eyes capable of 360-degree vision.
Three Times a Charm: The name "trilobite" means "three lobed." Looking at the trilobite from above, the three lobes are the "central axial lobe," which runs from head to tail down the middle of the body, and the two symmetrical "pleural lobes" that flank the central lobe on right and left. From head to tail, the trilobite is also divided in three parts. These sections are the "cephalon," or head, with eyes, mouth parts and antennae; a segmented thorax, which is the main body core; and a posterior or tail section called the "pygidium." |
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As seen in ANIMAL ARMAGEDDON:
Episode 1 — "Death Rays
 Watch the Animal Armageddon preview.
COULD YOU SURVIVE? Take the "Staying Afloat in the Age of Sea Creatures" QUIZ to find out.
Trilobites: CUTE or CREEPY? Rate their fright factor in Prehistoric Scary or Not?
Fascinated by creatures from the past? Meet more extinct animals at HowStuffWorks.com. |
MORE CREATURES: Creatures of the Fall of the Age of Fish »
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