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The Cambrian explosion (also known as Cambrian radiation [1] or Cambrian diversification) is an interval of time beginning approximately in the Cambrian period of the early Paleozoic, when a sudden radiation of complex life occurred and practically all major animal phyla started appearing in the fossil record.
By the middle of the following Cambrian Period, a very diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa. The increase in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life. [30] [31]
The Cambrian explosion was a period of rapid multicellular growth. Most animal life during the Cambrian was aquatic. Trilobites were once assumed to be the dominant life form at that time, [57] but this has proven to be incorrect. Arthropods were by far the most dominant animals in the ocean, but trilobites were only a minor part of the total ...
Previous land-based life would probably have required other chemicals to attenuate ultraviolet radiation. [42] 580–542 Ma Ediacaran biota, the first large, complex aquatic multicellular organisms. [64] 580–500 Ma Cambrian explosion: most modern animal phyla appear. [65] [66] 550–540 Ma
The Precambrian dates from around 3850 to 542 million years ago. The Neoproterozoic is characterized by a large glaciation event, followed by the appearance of the first multicellular body plans before the Cambrian Explosion. Until the late 1950s, the Precambrian was not believed to have hosted multicellular organisms.
In the second half of the 20th century, a number of fossil forms have been found in Proterozoic rocks, particularly in ones from the Ediacaran, proving that multicellular life had already become widespread tens of millions of years before the Cambrian Explosion in what is known as the Avalon Explosion. [27]
Exceptionally well preserved 500m year old fossils show Cambrian seas were more diverse than scientists had thought. Exquisite fossil finds shed new light on the 'Cambrian explosion', when oceans ...
The Cambrian is the first period of the Paleozoic Era and ran from 539 million to 485 million years ago. The Cambrian sparked a rapid expansion in the diversity of animals, in an event known as the Cambrian explosion , during which the greatest number of animal body plans evolved in a single period in the history of Earth.