Edgecombe, Gregory D. American Museum of Natural History, New York, New York.
Adrain, Jonathan Department of Geosciences, University of Iowa, Iowa City, Iowa.
Last reviewed:July 2021
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- Exoskeleton morphology
- Development and molting
- Ecology and macroevolution
- Related Primary Literature
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A class of extinct Paleozoic arthropods, occurring in marine rocks of Early Cambrian through Late Permian age. The members of the extinct arthropod class Trilobita are commonly known as trilobites (Fig. 1). With about 5000 described genera and 20,000 species, trilobites comprise one of the most diverse and best-known fossil groups (Fig. 2). Trilobite species diversity peaked during the Late Cambrian and then declined more or less steadily until the Late Devonian mass extinction. Only four families survived to the Mississippian, and only one family lasted until the group's Permian demise. The dominance of trilobites in most Cambrian marine settings is essential to biostratigraphic correlation of that system. The closest living relatives of the trilobites are the chelicerates, including spiders, mites, and horseshoe crabs (Xiphosurida). See also: Arthropoda; Cambrian; Chelicerata; Devonian; Extinction; Fossil; Olenellina; Paleozoic; Permian; Stratigraphy; Xiphosurida
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