Triassic Period Part 1

 The Triassic Period spans 50.6 million years, from 251.9 million years ago to 201.4 million years ago. It is the first and shortest period of the Mesozoic Era. It both started and ended with a major extinction event.

The Permian–Triassic extinction devastated terrestrial life. Diverse communities with complex food-web structures took 30 million years to reestablish.

The Triassic period ended with a mass extinction which was particularly severe in the oceans. All the marine reptiles disappeared except for the ichthyosaurs and plesiosaurs. Invertebrates like molluscs were severely affected. In the oceans, 22% of marine families and possibly half of marine genera went missing.

The vast supercontinent of Pangaea continued until the mid-Triassic, after which it began to gradually split into two separate landmasses, Laurasia to the north and Gondwana to the south.

During this time period, almost all the Earth's land mass was concentrated into a single supercontinent centered more or less on the equator and spanning from pole to pole. The Tethys Sea penetrated the east side of this continent for a good distance along the equator. There was an older branch of the ocean (called the Paleo-Tethys Ocean) north of the Tethys Sea that was now closed off by a group of moving islands that became a strip of land.

During the mid-Triassic, a similar sea penetrated along the equator from the west coast. This sea was not named in the article I read. All the rest of Pangaea's shores were surrounded by the world-ocean known as Panthalassa. Although it was not stated, my guess is that these 2 long seas coming from the east and the west along the equator finally met, and Pangaea was no more.

The sea level was consistently low compared to the other geological periods. The beginning of the Triassic saw the sea level at around present sea level, rising to about 10-20 m (30-60 ft) above sea level during the Early and Middle Triassic. Then the sea level began to rise, with it reaching up to 50 metres (150 ft) above the present sea level. It then began to decline, reaching a low of 50 metres below the present sea level, which continued into the next time period.

The global climate during the Triassic was mostly hot and dry, with deserts spanning much of Pangaea's interior. There is no evidence of glaciation at or near either pole. In fact, the polar regions were apparently moist and temperate, providing a climate suitable for forests and vertebrates, including reptiles. Pangaea's large size limited the moderating effect of the global ocean; it's continental climate was highly seasonal, with very hot summers and cold winters. The strong contrast between Pangea and the global ocean triggered intense monsoons.

The climate shifted and became more humid as Pangaea began to split apart. The Triassic may have mostly been a dry period, but evidence exists that it was punctuated by several episodes of increased rainfall in tropical and subtropical latitudes of the Tethys Sea and its surrounding land. It may be that volcanic activity helped trigger climate change during this period.

Next we'll take a look at the inhabitants of Earth during the Triassic Period.

https://en.wikipedia.org/wiki/Triassic