End–Triassic extinction event facts for kids

The End–Triassic extinction event marks the boundary between the Triassic and Jurassic periods, 199.6 million years ago. However, many of the extinctions occurred before then in the Upper Triassic.

Overall, this was one of the major extinction events of the Phanerozoic eon. It profoundly affected life on land and in the oceans. At least half of the species now known to have been living on Earth at that time went extinct.

A whole class (conodonts: extinct chordates); 20% of all marine families; all large crurotarsans (non-dinosaurian archosaurs); some remaining therapsids; and many of the large amphibians were wiped out.

The event emptied many ecological niches, and allowed 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.

Scientists have suggested several explanations for this event, but all have unanswered challenges:

• Asteroid impact: no known impact crater has been dated to coincide with the Triassic–Jurassic boundary.
• Gradual climate change or sea-level fluctuations during the Upper Triassic. Sea level was low at the end of the Triassic, and the climate on Pangaea was arid. However, this does not explain the suddenness of the extinctions.
• Massive volcanic eruptions would release carbon dioxide, which would cause intense global warming, or sulfur dioxide and aerosols, which would cause severe cooling. The flood basalts of the Central Atlantic Magmatic Province (CAMP) occurred at the Triassic-Jurassic boundary.

Images for kids

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  Conodonts were a major vertebrate group which died out at the end of the Triassic

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  Capitosaurs (such as this Mastodonsaurus) were among the major amphibian groups which went extinct at the T-J boundary, though many may have died out earlier.

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  Reptile extinction at the end of the Triassic is poorly understood, but phytosaurs (such as this Redondasaurus) went from abundant to extinct by the end of the Rhaetian.

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  The Manicouagan reservoir in Quebec, a massive crater formed by a Late Triassic impact. Radiometric dating has determined that it is about 13 million years older than the Triassic–Jurassic boundary, and thus an unlikely candidate for a mass extinction.

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  Maximum extent of CAMP volcanism at the Triassic-Jurassic boundary

See also

In Spanish: Extinción masiva del Triásico-Jurásico para niños