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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.
The Early Ordovician is the first epoch of the Ordovician period, corresponding to the Lower Ordovician series of the Ordovician system. It began after the Age 10 of the Furongian epoch of the Cambrian and lasted from 486.85 to 471.3 million years ago, until the Dapingian age of the Middle Ordovician .
The Ordovician Period of the Paleozoic Era, in the Phanerozoic Eon. This category contains events which happened in the Ordovician , a division of the geologic time scale . See geologic time scale for information about its divisions and how they relate to each other.
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.
The Sandbian is the first stage of the Upper Ordovician.It follows the Darriwilian and is succeeded by the Katian.Its lower boundary is defined as the first appearance datum of the graptolite species Nemagraptus gracilis around 458.2 million years ago.
The first pulse of the Late Ordovician Extinction has typically been attributed to the Late Ordovician Glaciation, which is unusual among mass extinctions and has made LOME an outlier. [47] Although there was a longer cooling trend in Middle and Lower Ordovician, the most severe and abrupt period of glaciation occurred in the Hirnantian stage ...
The Darriwilian is the upper stage of the Middle Ordovician.It is preceded by the Dapingian and succeeded by the Upper Ordovician Sandbian Stage. The lower boundary of the Darriwilian is defined as the first appearance of the graptolite species Undulograptus austrodentatus around 469.4 million years ago.
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