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Triassic Period: The Earth's Recovery From Mass Extinction

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Read on to learn all about the Triassic Period, a time when the Earth recovered from a major mass extinction event.

Read on to learn all about the Triassic Period, a time when the Earth recovered from a major mass extinction event.

What Was the Great Dying?

When one thinks of extinction events, the first that comes to mind is the asteroid that supposedly wiped out the dinosaurs around 65 million years ago.

Not only was this one of several extinction events in Earth's history, it was also far from being the worst.

"The Great Dying"

Around 252 million years ago, a mass extinction event that palaeontologists dub "the Great Dying" occurred. It's estimated that 90% of species were wiped out, including 85% to 95% of marine invertebrates and 70% of terrestrial vertebrates.

This was the most devastating extinction event in Earth's history. The cause is unknown. Volcanic activity and rising sea levels may have contributed.

Life gradually recovered during the Triassic Period, although the lack of coal deposits from the early Triassic indicates that it took a while for new lifeforms to emerge.

The Moschops capensis — a mammal that went extinct during the cataclysm that preceded the Triassic Period. It would have lived 265–260 million years ago.

The Moschops capensis — a mammal that went extinct during the cataclysm that preceded the Triassic Period. It would have lived 265–260 million years ago.

What Was the Triassic Period?

The Triassic Period occurred 252 to 201 million years ago.

It's defined by:

  • The rise of the dinosaurs
  • The splitting of the continents

It marked the beginning of the Mesozoic (Greek for "middle life") Era, which was made up of the Triassic, Jurassic and Cretaceous Periods.

The Forging of the Continents

Before the Triassic Period, Earth consisted of one supercontinent known as Pangea.

The continent had a large desert in the middle and was surrounded by a world-spanning ocean known as Panthalassa, which was twice the width of the modern-day Pacific.

The climate was warm and dry, and since the world was squeezed into one land mass, there wasn't as much biodiversity as there is today.

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There were no polar ice caps, nor was there an extreme climate difference between the Equator's south and north.

Most difficult for us to comprehend is that there was no grass. The plant — one of the most successful species in the history of evolution — hadn't yet appeared on the planet.

All the continents of the Earth originally formed one supercontinent: Pangea

All the continents of the Earth originally formed one supercontinent: Pangea

The Great Shift

During the course of the Triassic Period, tectonic activity on a level never seen before or since caused Pangea to break up. This process began around 200 million years ago.

The shallow seas on the margins of the continents rose and were gradually colonised by marine animals and coral reefs.

What Pangea might have looked like from space.

What Pangea might have looked like from space.

The Rise of the Reptiles

Some species, such as spiders, scorpions and centipedes, survived the mass extinction event. But for the most part, Earth was cleansed of life.

Out of the ashes emerged the Archosaurs ("ruling reptiles"), which included the dinosaurs.

Reptiles ruled the Earth, but not all of those reptiles were dinosaurs. Powerful Archosaurs that were not dinosaurs included the Postosuchus ("crocodile from post"), the T-Rex of the Triassic Period. It was basically a giant land-dwelling crocodile.

The Postosuchus — the "T-Rex of the Triassic Period" was an Archosaur, but not a dinosaur. It was more closely related to crocodiles.

The Postosuchus — the "T-Rex of the Triassic Period" was an Archosaur, but not a dinosaur. It was more closely related to crocodiles.

The Age of Giants Begins

The earliest dinosaur fossils date back 240 million years. One of the first dinosaurs to appear was the Coelophysis ("hollow form"), a bipedal, cannibalistic predator up to 3 meters in length.

228 million years ago, the first Pterosaurs — dinosaurs of the sky — arose. They were small, to begin with, but would grow to have a wingspan of 15 meters.

210 million years ago, the first giant herbivorous dinosaurs emerged, such as the Plateosaurus ("flat lizard"), which was 7 meters high.

The skeleton of a coelophysis — one of the world's earliest-known dinosaurs.

The skeleton of a coelophysis — one of the world's earliest-known dinosaurs.

Marine reptiles such as Ichthyosaurs roamed the ocean, while 4-meter crocodilian creatures known as Temnospondyls occupied the waterways. The ancestors of lizards, turtles, snakes and frogs would appear during this period.

Some strange creatures shared the earth with the dinosaurs, creatures that would never be seen again after the Triassic Period. These included the Placerias, a herd animal that looked like a cross between a hog, cow and turtle.

Herds of placerias once roamed the plains of what is now Arizona, but went extinct at the end of the Triassic Period.

Herds of placerias once roamed the plains of what is now Arizona, but went extinct at the end of the Triassic Period.

The End of the Triassic Period

Around 201 million years ago, Earth was subject to yet another extinction event, potentially caused by volcanic activity resulting from the breakup of Pangea.

This was nowhere near as destructive as the one that preceded the Triassic Period, but it wiped out most of the Archosaurs. Only dinosaurs, pterosaurs and crocodiles survived.

The staurikosaurus — a primitive dinosaur that lived in Brazil during the Late Triassic.

The staurikosaurus — a primitive dinosaur that lived in Brazil during the Late Triassic.

This marked the transition to the Jurassic Period and paved the way for dinosaurs to arise and become the dominant species on the planet.

Following the Triassic Period, dinosaurs  ruled the remainder of the Mesozoic Era, such the Tyrannosaurus Rex — king of the Cretaceous Period.

Following the Triassic Period, dinosaurs ruled the remainder of the Mesozoic Era, such the Tyrannosaurus Rex — king of the Cretaceous Period.

References

General Information. Britannica.

Davis, Josh. The Triassic Period: the rise of the dinosaurs. Natural History Museum UK.

Bagley, Mary. 2014, February 12. Triassic Period Facts: Climate, Animals & Plants. Live Science.

Triassic Period—251.9 to 201.3 MYA. National Park Service.

Triassic Period Facts. Eden UK TV.

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