| Early/Lower Ordovician | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
.png) A map of Earth as it appeared 480 million years ago during the Early Ordovician Epoch, Tremadocian Age | |||||||||||
| Chronology | |||||||||||
| |||||||||||
| Etymology | |||||||||||
| Chronostratigraphic name | Lower Ordovician | ||||||||||
| Geochronological name | Early Ordovician | ||||||||||
| Name formality | Formal | ||||||||||
| Usage information | |||||||||||
| Celestial body | Earth | ||||||||||
| Regional usage | Global (ICS) | ||||||||||
| Time scale(s) used | ICS Time Scale | ||||||||||
| Definition | |||||||||||
| Chronological unit | Epoch | ||||||||||
| Stratigraphic unit | Series | ||||||||||
| Time span formality | Formal | ||||||||||
| Lower boundary definition | FAD of the conodont Iapetognathus fluctivagus. | ||||||||||
| Lower boundary GSSP | Greenpoint section, Green Point, Newfoundland, Canada 49°40′58″N 57°57′55″W / 49.6829°N 57.9653°W | ||||||||||
| Lower GSSP ratified | 2000[5] | ||||||||||
| Upper boundary definition | FAD of the conodont Baltoniodus triangularis | ||||||||||
| Upper boundary GSSP | Huanghuachang section, Huanghuachang, Yichang, China 30°51′38″N 110°22′26″E / 30.8605°N 110.3740°E | ||||||||||
| Upper GSSP ratified | 2007[6] | ||||||||||
| Atmospheric and climatic data | |||||||||||
| Mean atmospheric O2 content | c. 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]
- ^ 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.
- ^ 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.
- ^ 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
- ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. September 2023. Retrieved November 10, 2024.
- ^ 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.
- ^ 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.
- ^ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. Retrieved 2024-06-04.