Tonian
| Tonian | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 A map of Earth as it appeared during the late Tonian, c. 750 Ma | |||||||||||||||
| Chronology | |||||||||||||||
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| Etymology | |||||||||||||||
| Name formality | Formal | ||||||||||||||
| Usage information | |||||||||||||||
| Celestial body | Earth | ||||||||||||||
| Regional usage | Global (ICS) | ||||||||||||||
| Time scale(s) used | ICS Time Scale | ||||||||||||||
| Definition | |||||||||||||||
| Chronological unit | Period | ||||||||||||||
| Stratigraphic unit | System | ||||||||||||||
| Time span formality | Formal | ||||||||||||||
| Lower boundary definition | Defined chronometrically | ||||||||||||||
| Lower GSSA ratified | 1991[3] | ||||||||||||||
| Upper boundary definition | Redefined chronometrically with an interim calibrated age of c. 720 Ma. GSSP is in progress.[4] (Previously defined chronometrically as 850 Ma)[3] | ||||||||||||||
| Upper boundary definition candidates | The first appearance of widespread glaciation.[5] | ||||||||||||||
| Upper boundary GSSP candidate section(s) | To be determined | ||||||||||||||
The Tonian (from Ancient Greek: τόνος, romanized: tónos, meaning "stretch") is the first geologic period of the Neoproterozoic Era. It lasted from 1000 to 720 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined by the ICS based on radiometric chronometry. The Tonian is preceded by the Stenian Period of the Mesoproterozoic Era and followed by the Cryogenian.
Rifting leading to the breakup of supercontinent Rodinia, which had formed in the mid-Stenian, occurred during this period, starting from 900 to 850 Mya.
Biology
[edit]The first putative metazoan (animal) fossils are dated to the middle to late Tonian (c. 890-800 Mya). The fossils of Otavia antiqua, which has been described as a primitive sponge by its discoverers and numerous other scholars, date back to about 800 mya. Even earlier sponge-like fossils have been reported in reefs dating back to 890 million years before the present, but their identity is highly debated.[6] This dating is consistent with molecular data recovered through genetic studies on modern metazoan species; more recent studies have concluded that the base of the animal phylogenetic tree is in the Tonian.[7]
Tonian rocks preserve some of the earliest fossils of macroalgae,[8] such as the benthic macroalgae from the Longfengshan biota of the Luotuoling Formation[9] or the green algae from the Dolores Creek Formation.[10]
The first large evolutionary radiation of acritarchs occurred during the Tonian. Vase-shaped microfossils abound in late Tonian sediments and represent the earliest testate amoebozoans.[11]
See also
[edit]- Boring Billion – Earth history, 1.8 to 0.8 billion years ago
- Neoproterozoic oxygenation event
References
[edit]- ^ Brain, C. K.; Prave, A. R.; Hoffmann, K. H.; Fallik, A. E.; Herd D. A.; Sturrock, C.; Young, I.; Condon, D. J.; Allison, S. G. (2012). "The first animals: ca. 760-million-year-old sponge-like fossils from Namibia". S. Afr. J. Sci. 108 (8): 1–8. doi:10.4102/sajs.v108i1/2.658.
- ^ Bernhard, Joan (11 June 2013). "Insights into foraminiferal influences on microfabrics of microbialites at Highborne Cay, Bahamas". Proceedings of the National Academy of Sciences of the United States of America. 110 (24): 9830–9834. Bibcode:2013PNAS..110.9830B. doi:10.1073/pnas.1221721110. PMC 3683713. PMID 23716649.
- ^ a b Plumb, K. A. (June 1, 1991). "New Precambrian time scale". Episodes. 14 (2): 139–140. doi:10.18814/epiiugs/1991/v14i2/005.
- ^ Shields, Graham A.; Halversonb, Galen P.; Porter, Susannah M. (2018). "Descent into the Cryogenian". Precambrian Research. 319: 1–5. Bibcode:2018PreR..319....1S. doi:10.1016/j.precamres.2018.08.015.
- ^ Shields-Zhou, Graham A.; Porter, Susannah; Halverson, Galen P. (2016). "A new rock-based definition for the Cryogenian Period (circa 720 – 635 Ma)". Episodes. 39 (1): 3–8. doi:10.18814/epiiugs/2016/v39i1/89231. ISSN 0705-3797.
- ^ Turner, Elizabeth C. (28 July 2021). "Possible poriferan body fossils in early Neoproterozoic microbial reefs". Nature. 596 (7870): 87–91. Bibcode:2021Natur.596...87T. doi:10.1038/s41586-021-03773-z. PMC 8338550. PMID 34321662.
- ^ Kliman, Richard M. (Apr 14, 2016). Encyclopedia of Evolutionary Biology. Academic Press. p. 251. ISBN 9780128004265.
- ^ Del Cortona, Andrea; Jackson, Christopher J.; Bucchini, François; Van Bel, Michiel; D’hondt, Sofie; Škaloud, Pavel; Delwiche, Charles F.; Knoll, Andrew H.; Raven, John A.; Verbruggen, Heroen; Vandepoele, Klaas; De Clerck, Olivier; Leliaert, Frederik (7 January 2020). "Neoproterozoic origin and multiple transitions to macroscopic growth in green seaweeds". Proceedings of the National Academy of Sciences of the United States of America. 117 (5): 2551–2559. doi:10.1073/pnas.1910060117. ISSN 0027-8424. PMC 7007542. PMID 31911467.
- ^ Jing, Yinghao; Chen, Zhong-Qiang; Anderson, Ross P.; Wang, Xue; Zheng, Zemin; Feng, Xueqian (November 2022). "Microscopic and geochemical analyses of the Tonian Longfengshan biota from the Luotuoling Formation (Hebei Province, North China) with taphonomic implications". Precambrian Research. 382: 106899. doi:10.1016/j.precamres.2022.106899. Retrieved 19 May 2024 – via Elsevier Science Direct.
- ^ Maloney, Katie M.; Halverson, Galen P.; Schiffbauer, James D.; Xiao, Shuhai; Gibson, Timothy M.; Lechte, Maxwell A.; Cumming, Vivien M.; Millikin, Alexie E.G.; Murphy, Jack G.; Wallace, Malcolm W.; Selby, David; Laflamme, Marc (22 March 2021). "New multicellular marine macroalgae from the early Tonian of northwestern Canada". Geology. 49 (6): 743–747. Bibcode:2021Geo....49..743M. doi:10.1130/G48508.1. ISSN 0091-7613. Retrieved 19 May 2024 – via GeoScienceWorld.
- ^ Tingle, Kelly E.; Porter, Susannah M.; Raven, Morgan R.; Czaja, Andrew D.; Webb, Samuel M.; Bloeser, Bonnie (18 January 2023). "Organic preservation of vase-shaped microfossils from the late Tonian Chuar Group, Grand Canyon, Arizona, USA". Geobiology. 21 (3): 290–309. Bibcode:2023Gbio...21..290T. doi:10.1111/gbi.12544. ISSN 1472-4677. PMID 36651474.
Further reading
[edit]- "Tonian Period". GeoWhen Database. Archived from the original on May 12, 2006. Retrieved January 5, 2006.
- Ogg, James G. (2004). "Status on Divisions of the International Geologic Time Scale". Lethaia. 37 (2): 183–199. Bibcode:2004Letha..37..183O. doi:10.1080/00241160410006492.
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