Fossil group

Trilobites (rare)

Arthropods · Cambrian – Permian

Extinct marine arthropods armoured with a three-lobed, segmented calcite exoskeleton and, often, complex compound eyes. They crawled and swam across Palaeozoic sea floors, were among the first complex animals, and are classic index fossils of the Cambrian; the group ended in the end-Permian extinction.

A broad fossil group rather than a single taxon — the units below record it among their fauna or flora.