Eras

Cambrian

KAM-bree-un

Citation Formats

General Reference

Earth and Environment Atlas. "Cambrian." Accessed August 30, 2026. https://earth.interactiveatlas.org/eras/cambrian.

APA Style

Earth and Environment Atlas. (n.d.). Cambrian. Retrieved August 30, 2026, from https://earth.interactiveatlas.org/eras/cambrian

BibTeX

@misc{earthandenvironmentatlas-cambrian,
  author = {Earth and Environment Atlas},
  title = {Cambrian},
  year = {2026},
  url = {https://earth.interactiveatlas.org/eras/cambrian},
  note = {Accessed August 30, 2026}
}

The first period of the Paleozoic and of the Phanerozoic eon, named for Cambria (Wales), where its rock sequences were first studied. It opens with the most rapid diversification of complex animal life the fossil record shows.

Facts

Rank

Period 1

Start (Million Years Ago)

538.8 1

Revised in early 2022 from the earlier figure of 541 Mya per the cited article.

End (Million Years Ago)

485.4 1

Cambrian-Ordovician boundary, ICS standard value.

Key Event

The Cambrian explosion: the rapid appearance in the fossil record of most major hard-bodied animal groups alive today. 1

Cross-Tradition Connections

In Discipline

Geochronology

Source Geologic Time Scale (Wikipedia)

Part Of

Paleozoic

Source Geologic Time Scale (Wikipedia)

Sources

1. Geologic Time Scale (Wikipedia)

Wikimedia FoundationView the Source

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