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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 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 periods of the Phanerozoic Eon.
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]
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.
Knowledge of precise climatic events decreases as the record goes further back in time. The timeline of glaciation covers ice ages specifically, which tend to have their own names for phases, often with different names used for different parts of the world. The names for earlier periods and events come from geology and paleontology.
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, [58] 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 ...
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