Trilobites (meaning 鈥榯hree lobes') are a well-known fossil group of extinct marine arthropods that form the class Trilobita. They existed from the early Cambrian to the Permian era.Colour printed illustration by Heinrich Harder from 鈥楾iere der Urwelt' Animals of the Prehistoric World; 1916; Hamburg. Heinrich Harder (1858-1935) was a German landscape artist and book illustrator. From a series of prehistoric creature cards published by the Reichardt Cocoa company. Natural historian Wilhelm Bolsche wrote the descriptive text.