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Tonian

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Tonian
1000 – ~720Ma
A map of the world as it appeared during the late Tonian, c. 750 Ma[citation needed]
Chronology
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitPeriod
Stratigraphic unitSystem
Time span formalityFormal
Lower boundary definitionDefined chronometrically
Lower GSSA ratified1991[3]
Upper boundary definitionRedefined 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 candidatesThe first appearance of widespread glaciation.[5]
Upper boundary GSSP candidate section(s)To be determined

TheTonian(fromAncient Greek:τόνος,romanized:tónos,meaning "stretch" ) is the firstgeologic periodof theNeoproterozoicEra.It lasted from 1000 to 720 Mya (million years ago). Instead of being based onstratigraphy,these dates are defined by theICSbased onradiometric chronometry.The Tonian is preceded by theStenianPeriod of theMesoproterozoicEra and followed by theCryogenian.

Riftingleading to the breakup ofsupercontinentRodinia,which had formed in the mid-Stenian, occurred during this period, starting from 900 to 850 Mya.

Biology[edit]

See also:Huainan biota

The first putativemetazoan(animal)fossilsare dated to the middle to late Tonian (c.890-800 Mya). The fossils ofOtavia antiqua,which has been described as a primitivespongeby its discoverers and numerous other scholars, date back to about 800 mya. Even earlier sponge-like fossils have been reported inreefsdating 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 animalphylogenetic treeis 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 largeevolutionary radiationofacritarchsoccurred during the Tonian. Vase-shaped microfossils abound in late Tonian sediments and represent the earliest testate amoebozoans.[11]

See also[edit]

References[edit]

  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".S. Afr. J. Sci.108(8): 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.PMC3683713.PMID23716649.
  3. ^abPlumb, K. A. (June 1, 1991)."New Precambrian time scale".Episodes.14(2): 139–140.doi:10.18814/epiiugs/1991/v14i2/005.
  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.ISSN0705-3797.
  6. ^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.PMC8338550.PMID34321662.
  7. ^Kliman, Richard M. (Apr 14, 2016).Encyclopedia of Evolutionary Biology.Academic Press. p. 251.ISBN9780128004265.
  8. ^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.ISSN0027-8424.PMC7007542.PMID31911467.Retrieved27 June2024.
  9. ^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.Retrieved19 May2024– via Elsevier Science Direct.
  10. ^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.ISSN0091-7613.Retrieved19 May2024– via GeoScienceWorld.
  11. ^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.ISSN1472-4677.PMID36651474.Retrieved5 June2024– via Wiley Online Library.

Further reading[edit]


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