Kambriums

Kambriums is a less common plural form sometimes used to refer to the Cambrian period, a major interval in the history of Earth’s geology and biology. In standard English, the period is called the Cambrian (singular) and Cambrian period. The name derives from Cambria, the Latin name for Wales, where early rocks helping define the period were studied.

The Cambrian lasted roughly from 541 to 485 million years ago. It is best known for the Cambrian Explosion, a rapid diversification of multicellular life that produced many major animal groups for the first time. During this time, skeletons and hard shells became widespread, changing marine ecosystems and the fossil record. The period closes with further evolutionary developments and the appearance of the first chordates in some late Cambrian deposits.

Fossil evidence from key sites such as the Burgess Shale in Canada and the Chengjiang biota in China has been crucial for understanding early animal life. These deposits preserve soft-bodied organisms as well as hard parts, revealing a broader range of forms than later fossil records. Notable Cambrian groups include early arthropods, plus various worm-like and echinoderm lineages; trilobites are among the most iconic fossils of the era.

Subdivisions of the Cambrian are often described in terms of lower, middle, and upper phases, with varying regional or formal schemes in use. Because “kambriums” is not the standard term in contemporary English, scientists typically refer to the Cambrian period or its divisions when discussing this interval.