The TRIASSIC–JURASSIC EXTINCTION EVENT marks the boundary between
Jurassic periods, 201.3 million years ago, and is
one of the major extinction events of the
Phanerozoic eon, profoundly
affecting life on land and in the oceans. In the seas, a whole class
(conodonts ) and 34% of marine genera disappeared. On land, all
archosaurs other than crocodylomorphs (
Crocodyliformes ) and
Avemetatarsalia (pterosaurs and dinosaurs ),
some remaining therapsids , and many of the large amphibians became
* 1 Effects
* 2 Current theories
* 3 References
* 4 Literature
* 5 External links
Ranges of families tetrapods through the
Triassic and Early
At least half of the species now known to have been living on Earth
at that time became extinct. This event vacated terrestrial ecological
niches , allowing the dinosaurs to assume the dominant roles in the
Jurassic period. This event happened in less than 10,000 years and
occurred just before
Pangaea started to break apart. In the area of
Germany ), a Triassic-
Jurassic bonebed can be found, which
is characteristic for this boundary.
Statistical analysis of marine losses at this time suggests that the
decrease in diversity was caused more by a decrease in speciation than
by an increase in extinctions.
Several explanations for this event have been suggested, but all have
* Gradual climate change , sea-level fluctuations or a pulse of
oceanic acidification during the late
Triassic reached a tipping
point . However, this does not explain the suddenness of the
extinctions in the marine realm.
* Asteroid impact, but so far no impact crater of sufficient size
has been dated to coincide with the Triassic–
Rochechouart crater in France has most recently been
dated to 201 ±2 million years ago, but at 25 km across (possibly up
to 50 km across originally), appears to be too small. The impact
responsible for the annular
Manicouagan Reservoir occurred about 12
million years before the extinction event - the
Rochechouart crater is
now thought to have been caused by part of the same fragmented
* Massive volcanic eruptions, specifically the flood basalts of the
Central Atlantic Magmatic Province (CAMP), would release carbon
dioxide or sulfur dioxide and aerosols , which would cause either
intense global warming (from the former) or cooling (from the latter).
The isotopic composition of fossil soils of end
Triassic and Early
Jurassic has been tied to a large negative carbon isotope excursion
(Whiteside et al. 2010). Carbon isotopes of lipids (n-alkanes )
derived from leaf wax and lignin , and total organic carbon from two
sections of lake sediments interbedded with the CAMP in eastern North
America have shown carbon isotope excursions similar to those found in
the mostly marine St. Audrie’s Bay section, Somerset, England; the
correlation suggests that the end-
Triassic extinction event began at
the same time in marine and terrestrial environments, slightly before
the oldest basalts in eastern North America but simultaneous with the
eruption of the oldest flows in Morocco (Also suggested by Deenen et
al., 2010), with both a critical CO2 greenhouse and a marine
biocalcification crisis. Contemporaneous CAMP eruptions, mass
extinction, and the carbon isotopic excursions are shown in the same
places, making the case for a volcanic cause of a mass extinction. The
catastrophic dissociation of gas hydrates (suggested as one possible
cause of the largest mass extinction of all time, the so-called "Great
Dying " at the end of the
Permian Period) may have exacerbated
* ^ Some sources (Whiteside et al 2010) give a date 201.4 Ma.
* ^ The extinction of conodonts —in terms of discrete elements—
at the Triassic-
* ^ Graham Ryder; David E. Fastovsky; Stefan Gartner (1996). The
Cretaceous-Tertiary Event and Other Catastrophes in Earth History.
Geological Society of America. p. 19. ISBN 9780813723075 .
* ^ Johannes Baier: Der Geologische Lehrpfad am Kirnberg (Keuper;
SW-Deutschland). - Jber. Mitt. oberrhein. geol. Ver, N. F. 93, 9-26,
* ^ Bambach, R.K.; Knoll, A.H.; Wang, S.C. (December 2004).
"Origination, extinction, and mass depletions of marine diversity".
Paleobiology . 30 (4): 522–542. doi
:10.1666/0094-8373(2004)0302.0.CO;2 . ISSN 0094-8373 .
* ^ T.M. Quan, B. van de Schootbrugge, M.P. Field, "Nitrogen
isotope and trace metal analyses from the Mingolsheim core (Germany):
Evidence for redox variations across the Triassic-
Global Biogeochemical Cycles, 22 2008: "a series of events resulting
in a long period of stratification, deep-water hypoxia, and
denitrification in this region of the Tethys Ocean basin"; M.
Hautmann, M.J. Benton, A. Toma, "Catastrophic ocean acidification at
Jurassic boundary", Neues Jahrbuch für Geologie und
Paläontologie 249.1, July 2008:119-127.
* ^ Schmieder, M.; Buchner, E.; Schwarz, W. H.; Trieloff, M.;
Lambert, P. (2010-10-05). "A Rhaetian 40Ar/39Ar age for the
Rochechouart impact structure (France) and implications for the latest
Triassic sedimentary record".
Meteoritics & Planetary Science . 45
Bibcode :2010M&PS...45.1225S. doi
* ^ Smith, Roff (2011-11-16). "Dark days of the Triassic: Lost
world". Nature . 479 (7373): 287–289.
doi :10.1038/479287a . PMID 22094671 . Retrieved 2011-11-18.
* ^ Tanner, L. H.; J. F. Hubert; et al. (7 June 2001). "Stability
of atmospheric CO2 levels across the Triassic/
Nature. 411 (6838): 675–677. doi :10.1038/35079548 . PMID 11395765 .
* ^ Blackburn, Terrence J.; Olsen, Paul E.; Bowring, Samuel A.;
McLean, Noah M.; Kent, Dennis V; Puffer, John; McHone, Greg; Rasbury,
Troy; Et-Touhami7, Mohammed (2013). "Zircon U-Pb Geochronology Links
Extinction with the Central Atlantic Magmatic
Province". Science. 340 (6135): 941–945. Bibcode
:2013Sci...340..941B. doi :10.1126/science.1234204 . PMID 23519213 .
* Hodych, J. P.; G. R. Dunning (1992). "Did the Manicougan impact
Triassic mass extinction?". Geology. 20: 51–54.
Bibcode :1992Geo....20...51H. doi :10.1130/0091-7613(1992)0202.3.CO;2
* McElwain, J. C.; D. J. Beerling ; F. I. Woodward (27 August 1999).
"Fossil Plants and Global Warming at the Triassic-
Science. 285 (5432): 1386–1390. doi :10.1126/science.285.5432.1386 .
PMID 10464094 .
* McHone, J.G. (2003), Volatile emissions of Central Atlantic
Magmatic Province basalts: Mass assumptions and environmental
consequences, in Hames, W.E. et al., eds., The Central Atlantic
Magmatic Province: Insights from Fragments of Pangea. American
Geophysical Union Monograph 136, p. 241-254.
* Tanner, L.H.; S.G. Lucas; M.G. Chapman (2004). "Assessing the
record and causes of Late
Triassic extinctions". Earth-Science
Reviews. 65 (1–2): 103–139.
Bibcode :2004ESRv...65..103T. doi
* Whiteside, Jessica H.; Paul E. Olsen; Timothy Eglinton; Michael E.
Brookfield; Raymond N. Sambrotto (March 22, 2010). "Compound-specific