Trilobites: Diversity (1 of 2)

Besides Dinosaurs, Trilobites are also a famous and well-studied species from prehistory.  Unlike Dinosaurs, who are two distinct groupings of animals artificially placed in one Superorder, Trilobites occur naturally as Class of Marine Arthropods.  This Class of ancient sea animals consists of 10 Orders, 150 families, 5000 genera, and 20,000 (and counting) discovered species.  Found worldwide, They differed according to the particular water depth, temperature and geography of the world’s oceans where They lived.

            All Trilobites have the same basic body plan, which consists of a head (cephalon), a body (thorax), and a tail (pygidium).  These marine animals received their name which means “three lobed” from their three side to side lobes – left (pleural), central (axial), and right.  Beyond this standard body, many Trilobites developed unique features such as sharp spines or horseshoe-shaped heads.

            This diversity in adaptation enabled Trilobites to be one of the longest surviving species in the world.  Believed to have emerged about 700 million years ago (mya) during the Pre-Cambrian Eon, Trilobites came into their own about 500 mya during the Cambrian Life Explosion.  Living through the entire Paleozoic Era (about 300 million years in duration), They became extinct during the Great Dying of the Permian Period (about 250 mya).

            Besides being noted for their longevity, Trilobites were also one of the first animals on earth to possess eyes.  Their eyes were made of calcite crystals laid out in rows of 100 to 15,000 lenses.  Using their eyes, Trilobites could sense movement, which helped Them to hunt as well as to hide from Predators.  Once early animals developed eyes, the predator-prey dynamic took hold.

            Since They were so common and widespread in the Paleozoic Era, Trilobites are studied in great detail by paleontologists to understand the processes of early evolution.  In fact, They were the first extinct animals to be studied by early scientists.  Since the fossils of Trilobites were readily found in Burgess-Shale type deposits, paleontologists could trace the beginning of complex life systems by examining the developments of Trilobites.