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Temporal range: Early Cambrian - Late Permian
Trilobite (meaning "three lobed") are extinct arthropods. Their name is in reference to the three round parts, called lobes, across their heads (cephalon), consisting of a slightly raised central lobe (the axis) and two flatter pleural lobes on either side. The entire bodies were also divided into three: the head (cephalon), thorax (chest) made up to a group of up to 30 segments and the tail (pygidium). Underneath and rarely preserved are three pairs of legs for the head and paired legs for each pleural groove. Trilobites are the earliest known animal to have vision. Some possessed eyes and some seem to have no eyes at all, while others had eyes made up of many parts that could see all around the animal. Trilobites ranged in length from 1 millimetre (0.04 in) to 72 centimetres (28 in), with a typical size range of 3–10 cm (1.2–3.9 in). The world's largest trilobite, Isotelus rex, was found in 1998 by Canadian scientists on the shores of Hudson Bay.
Butterflies of the Sea
Long before the fish lived in the seas and the Dinosaurs roamed the land, Trilobites appeared some 600 million years ago during the Cambrian period. They belonged to the phylum Arthropoda (joint-footed), a phylum which to this day represents the most successful (78%) of all animal life forms, including crabs, centipedes, spiders, shrimps and insects. The Trilobites, living in shallow seas, flourished as swimmers, crawlers and burrowers for some 350 million years. Over time, they evolved rapidly into a wide variety of strange and beautiful forms.
Discovery and origins
First capturing man's eye some 25,000 years ago in France where two specimens were found is association with a Cro-magnon settlement, at a site called "La Grotte du Trilobite", one was found with a hole drilled into it and worn as an adornment. Others have been found in the tombs of Egypt, Greece and Rome. Trilobite fossils were sold on the street of 15th Century Europe and collected by Thomas Jefferson and Benjamin Franklin, today they are collected, studied and enjoyed by people from all walks of life.
Trilobites appear to have been only marine dwelling creatures because their remains are always found in rocks that contain other marine life forms. However, within their marine environment, trilobites were found in many different conditions: from extremely shallow to very deep water. They lived in almost every ancient ocean, and their fossils are found on every continent.