Middle Ordovician Epoch
(Dyfed)
From 471.8 +/- 1.6 To 460.9 +/- 1.6 Ma
Start Defined By: Conodont, potentially lowest occurrence of Protoprioniodus
aranda or of Baltoniodus triangularis.
End Defined By: Graptolite, lowest occurrence of Nemagraptus gracilis.
Start Based On: Gradstein, Ogg, Smith, _A Geologic Time Scale 2004_
End Based On: Gradstein, Ogg, Smith, _A Geologic Time Scale 2004_
-- Overlaps With --
Australian Stage: Chewtonian (473 - 471)
North American Stage: Mohawkian (462 - 451)
-- A Substage of --
Eon: Phanerozoic (542 - -5.5012e-005)
Era: Paleozoic (542 - 251)
Period: Ordovician (488.3 - 443.7)
-- Preceeded By --
Epoch: Early Ordovician (488.3 - 471.8)
ICS Stage: Arenig (478.6 - 471.8)
Chinese Stage: Dawanian (472 - 471.8)
European Stage: Fennian (473.5 - 471.8)
North American Stage: Ibexian (491 - 471.8)
North American Stage: Cassinian (473 - 471.8)
-- Followed By --
Epoch: Late Ordovician (460.9 - 443.7)
ICS Stage: Ordovician V (460.9 - 455.8)
Australian Stage: Gisbornian (460.9 - 456)
Chinese Stage: Baotan (460.9 - 454.5)
European Stage: Aurelucian (460.9 - 457)
General Stage: Caradoc (460.9 - 449)
Regional Stage: Costonian (460.9 - 459)
-- Contains the Following Stages --
ICS Stage: Ordovician III (471.8 - 468.1)
ICS Stage: Darriwilian (468.1 - 460.9)
Australian Stage: Castlemanian (471 - 470)
Australian Stage: Ypeenian (470 - 468.1)
General Stage: Llanvirn (471.8 - 464)
General Stage: Llandeilo (464 - 460.9)
North American Stage: White Rockian (471.8 - 462)
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