The Cambrian Period (from a Latin form of the Welsh name for Wales) begins the Paleozoic Era about 544 mya, and comes to a close about 510 mya. it was during the Cambrian that life "exploded," developing almost all of the major groups in a relatively short time.
Originally, the bottom of the Cambrian was defined as the point where fossils began. Subsequently, older fossils have been found, and this definition is no longer valid. Now, it is roughly determined to be the point at which there is the first appearance of numerous fossil shells.
Classic Fossil-Bearing Sites
Chengjiang, China
Burgess Shale,
British Columbia, also, see here.
Wheeler Formation, Utah
Croixan Series, Minnesota, Wisconsin
No craterform structures are known from the Cambrian.
Significant Events
There is currently some debate concerning the rapidity of lifeform developments during the Cambrian Period but, regardless, it was during this time that almost all of the major lifeform types appeared on Earth.
Mass Extinction
The Cambrian ended with a mass extinction of about 75% of the trilobite families, half the sponge families, and many brachiopods and snails. The cause of the extinction is not known.
Cambrian Graphics
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| Brooksella |
Trilobite |
Arthropod |
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| Trilobite |
Dinomischus |
Eldonia |
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| Cambrian Seafloor |
Eurypterid |
Eurypterid |
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| Marella |
Miskoia |
Olenoides |
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| Hymenocaris |
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