Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between 247.2 Ma and 237 Ma (million years ago). It is preceded by the Early Triassic Epoch and followed by the Late Triassic Epoch. The Middle Triassic is divided into the Anisian and Ladinian ages or stages.
Middle Triassic | |||||||||||||||||||||||
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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 | Epoch | ||||||||||||||||||||||
Stratigraphic unit | Series | ||||||||||||||||||||||
Time span formality | Formal | ||||||||||||||||||||||
Lower boundary definition | Not formally defined | ||||||||||||||||||||||
Lower boundary definition candidates |
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Lower boundary GSSP candidate section(s) |
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Upper boundary definition | FAD of the Ammonite Daxatina canadensis | ||||||||||||||||||||||
Upper boundary GSSP | Prati di Stuores, Dolomites, Italy 46.5269°N 11.9303°E | ||||||||||||||||||||||
Upper GSSP ratified | 2008[6] |
Formerly the middle series in the Triassic was also known as Muschelkalk. This name is now only used for a specific unit of rock strata with approximately Middle Triassic age, found in western Europe.
Middle Triassic fauna
Following the Permian–Triassic extinction event, the most devastating of all mass-extinctions, life recovered slowly. In the Middle Triassic, many groups of organisms reached higher diversity again, such as the marine reptiles (e.g. ichthyosaurs, sauropterygians, thallatosaurs), ray-finned fish and many invertebrate groups like molluscs (ammonoids, bivalves, gastropods).
During the Middle Triassic, there were no flowering plants, but instead there were ferns and mosses. Small dinosauriforms began to appear, like Nyasasaurus and the ichnogenus Iranosauripus.
- Mixosaurus cornalianus restoration, a Middle Triassic ichthyosaur
References
- Widmann, Philipp; Bucher, Hugo; Leu, Marc; et al. (2020). "Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery". Frontiers in Earth Science. 8 (196): 196. Bibcode:2020FrEaS...8..196W. doi:10.3389/feart.2020.00196.
- McElwain, J. C.; Punyasena, S. W. (2007). "Mass extinction events and the plant fossil record". Trends in Ecology & Evolution. 22 (10): 548–557. doi:10.1016/j.tree.2007.09.003. PMID 17919771.
- Retallack, G. J.; Veevers, J.; Morante, R. (1996). "Global coal gap between Permian–Triassic extinctions and middle Triassic recovery of peat forming plants". GSA Bulletin. 108 (2): 195–207. Bibcode:1996GSAB..108..195R. doi:10.1130/0016-7606(1996)108<0195:GCGBPT>2.3.CO;2. Retrieved 2007-09-29.
- Payne, J. L.; Lehrmann, D. J.; Wei, J.; Orchard, M. J.; Schrag, D. P.; Knoll, A. H. (2004). "Large Perturbations of the Carbon Cycle During Recovery from the End-Permian Extinction". Science. 305 (5683): 506–9. Bibcode:2004Sci...305..506P. doi:10.1126/science.1097023. PMID 15273391. S2CID 35498132.
- Ogg, James G.; Ogg, Gabi M.; Gradstein, Felix M. (2016). "Triassic". A Concise Geologic Time Scale: 2016. Elsevier. pp. 133–149. ISBN 978-0-444-63771-0.
- Mietto, Paolo; Manfrin, Stefano; Preto, Nereo; Rigo, Manuel; Roghi, Guido; Furin, Stefano; Gianolla, Piero; Posenato, Renato; Muttoni, Giovanni; Nicora, Alda; Buratti, Nicoletta; Cirilli, Simonetta; Spötl, Christoph; Ramezani, Jahandar; Bowring, Samuel (September 2012). "The Global Boundary Stratotype Section and Point (GSSP) of the Carnian Stage (Late Triassic) at Prati Di Stuores/Stuores Wiesen Section (Southern Alps, NE Italy)" (PDF). Episodes. 35 (3): 414–430. doi:10.18814/epiiugs/2012/v35i3/003. Retrieved 13 December 2020.