Cambrian. The first appearance of trilobites defines the start of Series 2 of the Cambrian, and they can be found in strata up to the upper Permian, after which trilobites (among a large number of marine organisms) went extinct in the great catastrophe that removed over 90% of all species on earth. The greatest numbers of trilobite species occurred during the Cambrian and Ordovician periods, after which trilobite extinction trends exceeded radiation events.
UT Department of Environmental Sciences
The University of Toledo
Digital Initiatives, University of Toledo Libraries
environmental sciences; virtual exhibitions
"Phylum Arthropoda, Class Trilobita" (2017). Rock and Mineral Exhibit. 100.