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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.
Volcanic activity, particularly that of large igneous provinces, has been speculated to have been the cause of the environmental crisis. [3] The emplacement of the Namaqualand–Garies dykes in South Africa has been dated to 485 mya, the time at which the Cambrian–Ordovician extinction event occurred, although there remains no unambiguous evidence of a causal relationship between this ...
The Great Ordovician Biodiversification Event (GOBE) was an evolutionary radiation of animal life throughout [1] the Ordovician period, 40 million years after the Cambrian explosion, [2] whereby the distinctive Cambrian fauna fizzled out to be replaced with a Paleozoic fauna rich in suspension feeder and pelagic animals.
Oklahoma was a terrestrial environment for most of the ensuing Mesozoic era. [3] The Late Triassic Dockum Group of western Oklahoma preserved remains of archosaurs and temnospondyls, although its fossil record is restricted to a narrow region of the panhandle and is far sparser than the equivalent records in Texas, New Mexico, and Arizona. [98]
180 m; rising to 220 m in Caradoc and falling sharply to 140 m in end-Ordovician glaciations [8] The Ordovician ( / ɔːr d ə ˈ v ɪ ʃ i . ə n , - d oʊ -, - ˈ v ɪ ʃ ən / or-də- VISH -ee-ən, -doh-, - VISH -ən ) [ 9 ] is a geologic period and system , the second of six periods of the Paleozoic Era , and the second of twelve ...
The Cambrian (/ ˈ k æ m b r i. ə n, ˈ k eɪ m-/ KAM-bree-ən, KAYM-) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. [5] The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma.
The end-Cambrian mass extinction event marked a major change in trilobite fauna; almost all Redlichiida (including the Olenelloidea) and most Late Cambrian stocks became extinct. [23] A continuing decrease in Laurentian continental shelf area [ 28 ] is recorded at the same time as the extinctions, suggesting major environmental upheaval.
Fossil of the Cambrian-Middle Devonian trilobite Cheirurus †Cheirurus †Chonetes †Chonetes mesoloba †Cladochonus †Cleiothyridina †Cleiothyridina orbicularis †Clepsydrops; Cliona †Colobomycter – type locality for genus †Colobomycter pholeter – type locality for species †Composita †Composita mexicana †Composita rotunda