Question

What geological occurrence did the Permian-Triassic, Triassic-Jurassic and Cretaceous-Tertiary Extinctions have in common?

Answer 1

The Triassic Period, the Jurassic Period, and the Cretaceous Period form the 3 major divisions of the Mesozoic Era, from oldest to yongest.

The Mesozoic Era began 252.2 million years ago, following the conclusion of the Paleozoic Era (with the period Permian), and ended 66 million years ago, at the dawn of the Cenozoic Era (with the period Tertiary).

The Mesozoic was a time of geologic and biological transition. During this era the continents began to move into their present-day configurations.

Adistinct modernization of life-forms occurred, partly because of the demise of many earlier types of organisms.

Three of the five largest mass extinctions in Earth history are associated with the Mesozoic:

• a mass extinction occurred at the boundary between the Mesozoic and the preceding Paleozoic i.e, Permian - Triassic extinction.
  • during which approximately 90% to 96% of marine species and 70% of terrestrial vertebrates became extinct.
  • It is also known as the "Great Dying" because it is considered the largest mass extinction in the Earth's history.
• another occurred within the Mesozoic at the end of the Triassic Period i.e, Triassic- Jurassic extinction.
• and a third occurred at the boundary between the Mesozoic and subsequent Cenozoic i.e. the Cretaceous–Paleogene extinction event (or K–Pg extinction event)

-​​​​​​​Approximately 50% of all genera became extinct, including all of the non-avian dinosaurs.

Common events to all these 3 mass extinctions were:

• It was a time of significant tectonic, climate, and evolutionary activity.
• The era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses that would move into their current positions during the next era.
• The climate of the Mesozoic was varied, alternating between warming and cooling periods. Overall, however, the Earth was hotter than it is today.

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