Alexandrian Regional Stage
From 443.7 +/- 1.5 To 436 +/- 1.9 Ma
Start Defined By: Graptolites, lowest occurrences of Parakidograptus
acuminatus and Akidograptus ascensus.
End Defined By: Brachiopods, just above extinction of Eocoelia intermedia
and below lowest succeeding species Eocoelia curtisi. Near base of
Monograptus turriculatus graptolite zone.
Start Based On: Gradstein, Ogg, Smith, _A Geologic Time Scale 2004_
End Based On: Gradstein, Ogg, Smith, _A Geologic Time Scale 2004_
-- Overlaps With --
Chinese Stage: Shinulanian (438 - 433)
North American Stage: Niagaran (438 - 421.3)
-- A Substage of --
Eon: Phanerozoic (542 - -5.5012e-005)
Era: Paleozoic (542 - 251)
Period: Silurian (443.7 - 416)
Epoch: Early Silurian (443.7 - 422.9)
Sub-Epoch: Llandovery (443.7 - 428.2)
Australian Stage: Keiloran (443.7 - 433)
-- Preceeded By --
Period: Ordovician (488.3 - 443.7)
Epoch: Late Ordovician (460.9 - 443.7)
ICS Stage: Hirnantian (445.6 - 443.7)
Australian Stage: Bolindian (450 - 443.7)
General Stage: Ashgill (449 - 443.7)
North American Stage: Cincinnatian (451 - 443.7)
-- Followed By --
ICS Stage: Telychian (436 - 428.2)
-- Contains the Following Stages --
ICS Stage: Rhuddanian (443.7 - 439)
ICS Stage: Aeronian (439 - 436)
Chinese Stage: Longmaxian (443.7 - 438)
North American Stage: Medinan (443.7 - 438)
Regional Stage: Idwian (439 - 437.5)
Regional Stage: Fronian (437.5 - 436)
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