Triassic-Jurassic (Tr-J) Extinction Event (~182 Mya)

A Triassic-Jurassic (Tr-J) Extinction Event (~182 Mya) is an extinction event that marks the boundary between the Triassic and Jurassic periods.

• AKA: End-Triasic Extinction.
• Context:
  • …
• Counter-Example(s):
  • The Great Oxygenation Event.
  • Cretaceous–Paleogene Extinction Event (~66 Mya.).
  • Permian-Triassic Extinction Event (~252 Ma).
  • The Human-due Extinction Period.
  • The Superintelligences-due Extinction Period.
• See: Phanerozoic, Class (Biology), Conodont, Crurotarsi, Archosaur, Therapsid, Amphibia.

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References

2023

• (Wikipedia, 2023) ⇒ https://en.wikipedia.org/wiki/Triassic–Jurassic_extinction_event Retrieved:2023-6-5.
  • The Triassic–Jurassic (Tr-J) extinction event (TJME), often called the end-Triassic extinction, marks the boundary between the Triassic and Jurassic periods, , and is one of the top five major extinction events of the Phanerozoic eon, profoundly affecting life on land and in the oceans. In the seas, the entire class of conodonts and 23–34% of marine genera disappeared. On land, all archosauromorphs other than crocodylomorphs, pterosaurs, and dinosaurs became extinct; some of the groups which died out were previously abundant, such as aetosaurs, phytosaurs, and rauisuchids. Some remaining non-mammalian therapsids and many of the large temnospondyl amphibians had become extinct prior to the Jurassic as well. However, there is still much uncertainty regarding a connection between the Tr-J boundary and terrestrial vertebrates, due to a lack of terrestrial fossils from the Rhaetian (latest) stage of the Triassic. What was left fairly untouched were plants, crocodylomorphs, dinosaurs, pterosaurs and mammals; this allowed the dinosaurs, pterosaurs, and crocodylomorphs to become the dominant land animals for the next 135 million years. 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. Nevertheless, a pronounced turnover in plant spores and a collapse of coral reef communities indicates that an ecological catastrophe did occur at the Triassic-Jurassic boundary. Older hypotheses on extinction have proposed that gradual climate or sea level change may be the culprit, or perhaps one or more asteroid strikes. However, the most well-supported and widely-held theory for the cause of the Tr-J extinction places the blame on the start of volcanic eruptions in the Central Atlantic Magmatic Province (CAMP), which was responsible for outputting a high amount of carbon dioxide into Earth's atmosphere, inducing profound global warming, along with ocean acidification.

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