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Great South Gems & Minerals• Paradoxides Trilobite fossil display plate • | ||||
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F1450 - The brown shale matrix has been carefully chipped away to reveal this Paradoxides Trilobite which is approximately 500 million years old. This plate measures 9.75" tall x 12.25" wide (as oriented in the photo) and weighs 5.4 pounds. "Over 17,000 species of trilobites have been found and identified to date. And new species of trilobites are unearthed and described each year. Trilobites are truly remarkable, hard-shelled, segmented creatures that existed over 300 million years ago in the earth's ancient seas. The earliest trilobite known from the fossil record dates back some 543 million years and the last trilobites became extinct about 251 million years ago. Specimens of trilobite have been found as small as one-eighth of an inch long to over 28" long. All 17,000 plus trilobites can be classed in nine orders, over 150 families, and about 5,000 genera. The trilobites were among the earth's ARTHROPODS. Trilobites had an outer segmented shell and were there exoskeleton, wearing their skeleton on the outside it's body, like todays lobster. All trilobite fossils have a similar body plan, being made up of three main body parts: A cephalon, or head, a segmented thorax, or main body section, and pygidium, or tail section. Therefore the name, trilobite, meaning three-sectioned. Trilobites hatched from eggs as tiny larva. As the trilobite grew it shed its exoskeleton, or outer shell, in a process of molting. The trilobite would have molted a number of times during it life span. This accounts for the large number of trilobite fossils, as a single trilobite would have left a number of shed exoskeletons behind. This also explains why it is that many trilobite fossils have what appears broken, or separated, skeleton segments. Some species of trilobite lived in shallow seas and had large eyes while other trilobite species were blind, probably living too deep in the sea for light to reach them. The trilobite also had antennae that perhaps were used for taste and smell. According to some scientist, the closest extant relatives of the trilobite may be the horseshoe crabs. WYSIWYG
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