Geographical Timeline

Cambrian Period

538.8 million to 485.4 million years ago

25+

Epoch one of the Cambrian period saw the early expansion of a Bilaterian trace fossil and the early expansion of a skeletal body fossil (Babcock).

Epoch Facts:

The Cambrian Period saw a rapid explosion of life in the oceans, also known as the Cambrian explosion. This explosion leads to a massive diversification of marine animals emerging on to the planet's ecosystems.

During this period, Earth's landmasses were mostly barren, with shallow seas covering much of the planet. The climate of this period was also relatively warm but had possible glacial-interglacial cycles in the later portions (Peng).

Epoch two experienced early diversification of marine animal clades, most notably among the arthropods (Babcock).

Epoch 3 was a time of major intraclade expansion of bilaterians or animals with bilateral symmetry (Babcock).

References

References

Babcock, Loren E., et al. "Global climate, sea level cycles, and biotic events in the Cambrian Period." Palaeoworld 24.1-2 (2015): 5-15.

Peng, Sh Ch, Loren E. Babcock, and Per Ahlberg. "The cambrian period." Geologic time scale 2020. Elsevier, 2020. 565-629.