Cambrian explosion
Period of major evolutionary diversification of animal life / From Wikipedia, the free encyclopedia
The Cambrian explosion (also known as Cambrian radiation[1] or Cambrian diversification) is an interval of time approximately 538.8 million years ago 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.[2][3][4] It lasted for about 13[5][6][7] to 25[8][9] million years and resulted in the divergence of most modern metazoan phyla.[10] The event was accompanied by major diversification in other groups of organisms as well.[lower-alpha 1]
Before early Cambrian diversification,[lower-alpha 2] most organisms were relatively simple, composed of individual cells, or small multicellular organisms, occasionally organized into colonies. As the rate of diversification subsequently accelerated, the variety of life became much more complex, and began to resemble that of today.[12] Almost all present-day animal phyla appeared during this period,[13][14] including the earliest chordates.[15]
Key Cambrian explosion events | ||||||||||||||||||||||||||||||
−590 — – −580 — – −570 — – −560 — – −550 — – −540 — – −530 — – −520 — – −510 — – −500 — – −490 — – | "Stage 2" "Stage 3" "Stage 4" "Stage 5" "Stage 10" * * * * * * * * * * * * * * * * * * * * * * * * * Baykonur glaciation * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * |
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