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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.

History

The Tonian was defined in 1990 by the New Precambrian time scale as being from 1000 to 850 Mya.[6] The name Tonian comes from Ancient Greek: τόνος, romanized: tónos, which means “stretch”, referring to the rifting that broke up Rodinia during this period.[7] The upper definition was then redefined to 720 Mya in 2014 after discoveries that the original 850 Mya for the lower Cryogenian and the first glaciations at 717 Mya did not match. This is temporary until the basal Cryogenian GSSP is chosen.[8][7]

Geology

Both the Supercontinent Rodinia and the Mirovian superocean remained stable throughout the early Tonian from 1000 to at least 900 Mya. The appearance of sedimentary rocks in multiple places in 850 to 800 Mya has been postulated as an initial breakup of Rodinia. However, there has been little evidence for the breakup of Rodinia during the mid-Tonian, with most agreeing that Rodinia began breaking up at the end of the Tonian, around 750 Mya.[7][9]

The first half of the Tonian has mildly fluctulating carbon isotope values, being transitional from the lower Mesoproterozoic levels to the higher Tonian levels. The later half of the Tonian has high carbon isotope values, with deep excursions happening at least once after 740 Mya, immediately before the Sturtian glaciation in the Cryogenian.[7]

Biology

See also: Huainan biota

The first putative metazoan (animal) fossils are dated to the middle to late Tonian (c. 890 to 800 Ma). Fossils of Otavia antiqua, which has been described as a primitive sponge by its discoverers and numerous other scholars, date back to about 800 Ma. Even earlier sponge-like fossils have been reported in reefs dating back to 890 Ma, but their identity is highly debated.[10] 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.[11][7]

Tonian rocks preserve some of the earliest known fossils of macroalgae,[12] such as the benthic macroalgae from the Longfengshan biota of the Luotuoling Formation[13] or the green algae from the Dolores Creek Formation.[14] Arctacellularia tetragonala, an alga found in this period, has chlorophyll derivatives preserved in it.[15] Sinosabellidites huainanensis, another alga from the Huainan biota that was initially confused for an animal, was found in this period.[16]

The first large evolutionary radiation of acritarchs occurred during the Tonian. Late Tonian sediments abound in vase-shaped microfossils that represent the earliest known testate amoebozoans.[17] Stromatolites begin to swiftly decrease during this period.[18]

Fungi are visibly preserved in this period in 810 to 715 million year old shale in the Mbuji-Mayi Supergroup with mycelia-like filaments.[19]

See also

References

  1. ^ 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”. South African Journal of Science. 108 (1/2): 1–8. doi:10.4102/sajs.v108i1/2.658.
  2. ^ 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.
  3. ^ a b Plumb, Kenneth A. (June 1991). “New Precambrian time scale”. Episodes. 14 (2): 139–140. doi:10.18814/epiiugs/1991/v14i2/005. eISSN 2586-1298. ISSN 0705-3797. LCCN 78646808. OCLC 4130038. S2CID 126954461. Open access icon
  4. ^ 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.
  5. ^ 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.
  6. ^ Plumb, K. A. (1991-06-01). “New Precambrian time scale”. Episodes Journal of International Geoscience. 14 (2): 139–140. doi:10.18814/epiiugs/1991/v14i2/005.
  7. ^ a b c d e Gradstein, Felix M.; Ogg, James G.; Schmitz, Mark D.; Ogg, Gabi M. (January 2020). Geologic Time Scale 2020 – The Tonian and Cryogenian Periods. Candice Janco. pp. 495–519. ISBN 978-0-12-824362-6.{{cite book}}: CS1 maint: date and year (link)
  8. ^ Shields, Graham A.; Halverson, Galen P.; Porter, Susannah M. (2018-12-01). “Descent into the Cryogenian”. Precambrian Research. Descent into the Cryogenian. 319: 1–5. doi:10.1016/j.precamres.2018.08.015. ISSN 0301-9268.
  9. ^ Li, Z. X.; Bogdanova, S. V.; Collins, A. S.; Davidson, A.; De Waele, B.; Ernst, R. E.; Fitzsimons, I. C. W.; Fuck, R. A.; Gladkochub, D. P.; Jacobs, J.; Karlstrom, K. E.; Lu, S.; Natapov, L. M.; Pease, V.; Pisarevsky, S. A. (2008-01-05). “Assembly, configuration, and break-up history of Rodinia: A synthesis” (PDF). Precambrian Research. Testing the Rodinia Hypothesis: Records in its Building Blocks. 160 (1): 179–210. doi:10.1016/j.precamres.2007.04.021. ISSN 0301-9268.
  10. ^ 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.
  11. ^ Kliman, Richard M. (Apr 14, 2016). Encyclopedia of Evolutionary Biology. Academic Press. p. 251. ISBN 978-0-12-800426-5.
  12. ^ 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.
  13. ^ 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.
  14. ^ 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. hdl:11343/281555. ISSN 0091-7613. Retrieved 19 May 2024 – via GeoScienceWorld.
  15. ^ Sforna, Marie Catherine; Loron, Corentin C.; Demoulin, Catherine F.; François, Camille; Cornet, Yohan; Lara, Yannick J.; Grolimund, Daniel; Ferreira Sanchez, Dario; Medjoubi, Kadda; Somogyi, Andrea; Addad, Ahmed; Fadel, Alexandre; Compère, Philippe; Baudet, Daniel; Brocks, Jochen J. (2022-01-10). “Intracellular bound chlorophyll residues identify 1 Gyr-old fossils as eukaryotic algae”. Nature Communications. 13 (1): 146. doi:10.1038/s41467-021-27810-7. ISSN 2041-1723. PMC 8748435.
  16. ^ Dong, Lin; Xiao, Shuhai; Shen, Bing; Yuan, Xunlai; Yan, Xianqin; Peng, Yongbo (2008-02-18). “Restudy of the worm-like carbonaceous compression fossils Protoarenicola, Pararenicola, and Sinosabellidites from early Neoproterozoic successions in North China”. Palaeogeography, Palaeoclimatology, Palaeoecology. The Dawn of Animal Life: Evolutionary and Palaeoecological Patterns in the Neoproterozoic-Cambrian Animal Fossil Record. 258 (3): 138–161. doi:10.1016/j.palaeo.2007.05.019. ISSN 0031-0182.
  17. ^ 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.
  18. ^ Bernhard, Joan M.; Virginia P., Edgcomb; Visscher, Pieter T.; Jeglinski, Marleen (May 28, 2013). “Insights into foraminiferal influences on microfabrics of microbialites at Highborne Cay, Bahamas”. PNAS. doi:10.1073/pnas.1221721110. PMC 3683713. PMID 23716649. Retrieved 2026-03-25.
  19. ^ Bonneville, S.; Delpomdor, F.; Préat, A.; Chevalier, C.; Araki, T.; Kazemian, M.; Steele, A.; Schreiber, A.; Wirth, R.; Benning, L. G. (2020-01-22). “Molecular identification of fungi microfossils in a Neoproterozoic shale rock”. Science Advances. 6 (4) eaax7599. doi:10.1126/sciadv.aax7599. PMC 6976295. PMID 32010783.

Further reading