Trilobites are arthropods with a characteristic longitudinal and transverse tripartition that was name giving. They are not only abundant in various shelf deposits but are helpful as index fossils and to characterize biofacies and paleobiogeography. Despite the relatively strong faunal provincialism, Cambrian trilobites constitute the biostratigraphical framework that allows to compare rock successions from regions on different Cambrian continents. Cephalopyge notabilis Zone, Jbel Warmast Formation, Tarhoucht section, eastern Anti-Atlas. Middle Cambrian Stephen Formation, Burgess Shale at Walcott Quarry, Yoho N.P., Canada.
Arthropods are apparently the most diverse of the Cambrian animal groups.
Numerous enigmatic forms with strongly differing cephalic appendages are known, especially from the various fossil archives. Bivalved arthropods of ostracod aspect but with phosphatic shell are important fossils in several regions. Brachiopods are relatively frequent but rarely abundant fossils. The first articulate brachiopod groups occur at the end of the Early Cambrian. Conodonts are important are biostratigraphic tools in the Upper Cambrian.