Early Ordovician

Early/Lower Ordovician
485.4 ± 1.9 – 470.0 ± 1.4 Ma
Map of Earth as it appeared 480 million years ago during the Early Ordovician, Tremadocian age[citation needed]
Chronology
Etymology
Chronostratigraphic nameLower Ordovician
Geochronological nameEarly Ordovician
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitEpoch
Stratigraphic unitSeries
Time span formalityFormal
Lower boundary definitionFAD of the conodont Iapetognathus fluctivagus.
Lower boundary GSSPGreenpoint section, Green Point, Newfoundland, Canada
49°40′58″N 57°57′55″W / 49.6829°N 57.9653°W / 49.6829; -57.9653
Lower GSSP ratified2000[5]
Upper boundary definitionFAD of the conodont Baltoniodus triangularis
Upper boundary GSSPHuanghuachang section, Huanghuachang, Yichang, China
30°51′38″N 110°22′26″E / 30.8605°N 110.3740°E / 30.8605; 110.3740
Upper GSSP ratified2007[6]
Atmospheric and climatic data
Mean atmospheric O2 contentc. 11.5 vol %
(55 % of modern)

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 485.4 ± 1.9 to 470 ± 1.4 million years ago, until the Dapingian age of the Middle Ordovician. It includes Tremadocian and Floian ages.[7]

  1. ^ Wellman, C.H.; Gray, J. (2000). "The microfossil record of early land plants". Phil. Trans. R. Soc. B. 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. PMC 1692785. PMID 10905606.
  2. ^ Korochantseva, Ekaterina; Trieloff, Mario; Lorenz, Cyrill; Buykin, Alexey; Ivanova, Marina; Schwarz, Winfried; Hopp, Jens; Jessberger, Elmar (2007). "L-chondrite asteroid breakup tied to Ordovician meteorite shower by multiple isochron 40 Ar- 39 Ar dating". Meteoritics & Planetary Science. 42 (1): 113–130. Bibcode:2007M&PS...42..113K. doi:10.1111/j.1945-5100.2007.tb00221.x.
  3. ^ Lindskog, A.; Costa, M. M.; Rasmussen, C.M.Ø.; Connelly, J. N.; Eriksson, M. E. (2017-01-24). "Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification". Nature Communications. 8: 14066. doi:10.1038/ncomms14066. ISSN 2041-1723. PMC 5286199. PMID 28117834. It has been suggested that the Middle Ordovician meteorite bombardment played a crucial role in the Great Ordovician Biodiversification Event, but this study shows that the two phenomena were unrelated
  4. ^ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
  5. ^ Cooper, Roger; Nowlan, Godfrey; Williams, S. H. (March 2001). "Global Stratotype Section and Point for base of the Ordovician System" (PDF). Episodes. 24 (1): 19–28. doi:10.18814/epiiugs/2001/v24i1/005. Archived (PDF) from the original on 2024-03-25. Retrieved 2024-06-04.
  6. ^ Chen, Xu; Bergström, Stig; Zhang, Yuan-Dong; Fan, Jun-Xuan (2009). "The base of the Middle Ordovician in China with special reference to the succession at Hengtang near Jiangshan, Zhejiang Province, southern China" (PDF). Lethaia. 42 (2): 218–231. Bibcode:2009Letha..42..218C. doi:10.1111/j.1502-3931.2008.00148.x. Archived (PDF) from the original on 2024-01-06. Retrieved 2024-06-04.
  7. ^ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. Retrieved 2024-06-04.