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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 in Britain was traditionally broken into Early (Tremadocian and Arenig), Middle (Llanvirn (subdivided into Abereiddian and Llandeilian) and Llandeilo) and Late (Caradoc and Ashgill) epochs. The corresponding rocks of the Ordovician System are referred to as coming from the Lower, Middle, or Upper part of the column.
Recent estimates (ICS and Cosuna) place the beginning of Gasconadian, and Ordovician, anywhere from about 488 to 500 million years ago, with a duration ranging from 9.7 to 10 million years respectively putting the end about 464 m.y.a. Both give estimates of over half the Early Ordovician. 60 percent according to the ICS, 2/3 according to Cosuna.
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This category includes biological taxa of rank more inclusive than genus that evolved during the Ordovician period of geologic time, between 485.4 and 443.8 million years ago, as well as genera and species that evolved during this time and persisted across multiple geological periods
The Floian is the second stage of the Ordovician Period. It succeeds the Tremadocian with which it forms the Lower Ordovician series. It precedes the Dapingian Stage of the Middle Ordovician. The Floian extended from 477.1 to 471.3 million years ago. [7]
Biological taxa that first appeared during the Early Ordovician epoch of geologic time, between 485.4 and 470 million years ago. See also the preceding Category:Furongian first appearances and the succeeding Category:Middle Ordovician first appearances
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.