We explain what the Triassic Period was, how it is divided and the climate it presents. Also, what are its characteristics, flora and fauna.

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In the Triassic the reptiles began to dominate both the land and the seas.

What was the Triassic Period?

The Triassic Period is the early period of the Mesozoic era of the geological time scale (which began 252.2 million years ago and ended 66 million years ago). Together with the later Jurassic and Cretaceous periods, they constitute the reign of the dinosaurs on Earth.

The Triassic Period lasted from 251 million years ago to approximately 201 million years ago, a period that begins and culminates with two mass extinction events of the species: the Permian-Triassic and the Triassic-Jurassic. This allows a more precise setting of its time limits.

Its name comes from the three rock strata that the German paleontologist Friedrich August von Alberti identified in the first fossil finds from that period, in central Germany, in 1834. The Triassic is the first geological period in which dinosaur fossils appear.

See also: Neolithic

Previous period

The Permian Period is the last of the Paleozoic Era., prior to the Mesozoic. It is temporarily located between 299 and 251 million years ago.

In this age the world consisted of two large continents, Siberia and Pangeasurrounded by a global ocean called Panthalassa.

there took place the first diversification of living beings into four ancestral groups: mammals, turtles, lepidosaurs, and archosaurs.

the permian culminated in the largest known extinction in the history of life on the planet, the Permian-Triassic mass extinction. 70% of terrestrial species were eliminated and 90% of marine species. Also at its end, Pangea, a “C” shaped macrocontinent, was formed.

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Triassic Period Division

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The Upper Triassic begins about 247.2 million years ago.

The Triassic is divided into three Epochs or Series, which comprise seven Ages or Floors throughout its 50 million years:

  • Lower or Early Triassic. It begins approximately 251.9 million years ago and culminates about 251.2 million years ago, comprising the Induense and Olenekiense ages.
  • middle triassic. It begins about 247.2 million years ago and ends 242 million years ago more or less, spanning the Anisian and Ladinian ages.
  • Upper or Late Triassic. It begins about 237 million years ago and ends about 208.5 million years ago, spanning the Carnian, Norian, and Rhaetian ages.

Geological features of the Triassic

At the beginning of the Triassic, the two continents known in earlier times were unified into one, in the shape of a “C”, known as Pangea.

In the central hole was the Sea of ​​Tethys.. It separated its two great continental portions, known as Laurasia (North America, Europe, and Asia) and Gondwana (South America, Africa, Arabia, India, and Antarctica).

At the end of the Triassic, Pangea showed its first signs of separation, as gaps emerged between North America, Eurasia and Africa. The sea level began a slow rise that culminated at the end of the Mesozoic Era. However, it still did not significantly reduce the portion of the planet’s surface above water.

Triassic climate

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Pangea’s enormous size made it difficult for the oceans to cool.

The world’s climate in the Triassic it was warm and dry. The summers were very intense and the winters very cold, especially in the equatorial region, which probably received water from strong monsoons annually.

However, Pangea’s enormous size made it difficult for the oceans to cool, producing deserts and evaporites within. There is no evidence of the presence of glaciers at the poles at the time, but of a temperate climate suitable for reptiles.

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Triassic flora

Since land plants did not suffer like other species during the extinction at the end of the Permian, they did not show very significant evolutionary changes during the Triassic.

Broadly speaking, it can be classified according to its place in location.

  • Laurasia. Cycads, adapted to a dry and hot climate, proliferated, along with ginkgos and conifers
  • Gondwana. Its humid climate allowed the growth of giant ferns and voluminous conifers, which came to populate entire regions, giving rise to Triassic forests.

petrified forests

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In Argentina there are petrified trees that come from the Triassic.

petrified forests are archaeological sites of fossilized trees. For a tree to petrify, all its organic matter had to be gradually replaced by minerals. Many Triassic trees today are found in petrified forests.

An example are those abound in the Paramillos de Upsallata, in Mendoza, Argentina. This Middle Triassic petrified forest is in a life position, and consists of more than 120 fossil trunks of an evergreen subtropical forest. It was discovered on his voyage around the world by Charles Darwin in 1835.

Triassic fauna

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During the Triassic the terrestrial surface was dominated by reptilian life.

Triassic animals can be distinguished into three categories:

  • Survivors of the Permian-Triassic extinction
  • New species that lived again and perished at the end of the Triassic.
  • New species that survived the Jurassic.

Both categories of new species took advantage of the void left by species that disappeared during the extinction.

The earth’s surface was dominated by reptilian life during this time. Among them, the mammalian reptiles stood out, who left the legacy of the true Jurassic mammals.

the other species evolved into large herbivorous and carnivorous reptiles, as well as large insects. Membranous reptile species were capable of gliding from one tree to another, but not proper flight.

Dinosaurs appeared at the end of the Triassic and they quickly colonized the Earth, since they lacked competition. Some of the earliest species were Procompsognathus and Plateosaurus.

In the sea, the predominant predator of the abundant molluscs (especially ammonoids) was the Ichthyosaur, which evolved rapidly at the beginning of the Triassic. Gradually it was losing its reptilian forms, in favor of others more similar to those of the modern dolphin.

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there would also be other aquatic reptiles towards the end of the period, such as the Nothosaurus, Lariosaurus or Askeptosaurus. The corals would appear in the middle Triassic.

Triassic-Jurassic mass extinction

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The mass extinction guaranteed the success of the dinosaurs in the Jurassic.

At the end of the Triassic, another mass extinction of land and sea species occurred, although not as severe as that of the late Permian. It is estimated that 20% of marine biological families disappearedmost archosaurs, therapsids, and large amphibians.

this extinction guaranteed the success of dinosaurs in the Jurassic, opening niches without competition on land and sea. The cause of this event is unknown, although the hypotheses oscillate between climatic changes, changes in marine chemistry or massive volcanic eruptions.

Main deposits of the Triassic

Some of the largest paleontological sites of the Triassic Period are found in:

  • South Africa. Karoo and the Elliot Formation.
  • Antarctica. The Mount Kirkpatrick Formation.
  • India. The Maleri Formation.
  • Australia. The Knocklofty Formation and the Wianamatta Series.
  • USA. Ghost Ranch (New Mexico), Lockatong Formation (New Jersey).
  • Argentina. Ischigualasto (San Juan) and Uspallata (Mendoza).
  • Brazil. Paleorrota (Rio Grande do Sul).

Later period: the Jurassic

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In the Jurassic began the fracture of the supercontinent Pangea.

The Jurassic Period started 201 million years ago and ended 145 million years ago. It was the period in which the dinosaurs proliferated and reigned, which is why it is perhaps the most famous of the Mesozoic periods.

In said period the fracturing of the supercontinent Pangea beganthe great dinosaurs proliferated, which conquered the land, the sea and even the air.

References:

  • “Triassic” on Wikipedia.
  • “Triassic Period”in Dinosauriopedia.
  • “Triassic Period” in National Geographic.
  • “Triassic Period Facts: Climate, Animals & Plants” in Live Science.
  • “Triassic Period” in The Encyclopaedia Britannica.

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