Cambrian

The first period of the Paleozoic Era, spanning about 539 to 485 million years ago. Its rocks preserve the diversification of many animal groups, including the earliest widely recognized fossil record of complex animals.

Ediacaran biota: Assemblages of mostly soft-bodied organisms that lived during the Ediacaran Period before the Cambrian. These earlier communities show what preceded the Cambrian’s animal diversification.
Burgess Shale: A fossil deposit in British Columbia renowned for exceptionally preserved Middle Cambrian organisms. Its soft-bodied fossils exposed a diversity of Cambrian animals absent from many other deposits.
Geologic time scale: A system that divides Earth’s history into nested units based on rocks, fossils, and chronology. The Cambrian is one named period within this hierarchy of geological time.
Ediacaran: The final period of the Neoproterozoic Era, preceding the Cambrian. The Ediacaran immediately precedes the Cambrian and contains earlier animal communities.
Predation: An ecological interaction in which one organism captures and consumes another. Predator–prey interactions intensified during the Cambrian and may have driven new defenses.
Chengjiang biota: An exceptionally preserved Early Cambrian fossil assemblage from Yunnan, China. It preserves early animals and tissues from near the start of the Cambrian diversification.
Paleozoic: The geologic era that began with the Cambrian and ended with the Permian. The Cambrian opens this era of Earth history.
Ordovician: The period following the Cambrian, spanning about 485 to 444 million years ago. The Ordovician begins where the Cambrian ends and continues marine diversification.
Biomineralization: The production of minerals by organisms to form structures such as shells and skeletons. The spread of mineralized skeletons made more Cambrian animals visible in the fossil record.
Sirius Passet: An Early Cambrian fossil locality in northern Greenland with exceptionally preserved marine organisms. Its fossils provide an Arctic comparison to other early Cambrian communities.

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