The word "Triassic" makes us think of ferocious dinosaurs roaming the Earth. But what was the Triassic period, and how did dinosaurs evolve?
One giant continent
Earth's continents are always slowly moving. About 250 million years ago, all the continents were actually one huge "super-continent" surrounded by one enormous ocean. Slowly, this giant continent, called Pangaea, broke apart and moved to form the continents we know today.
The Triassic period was a unique time in Earth's history, and it began on Pangaea.
During this time, the climate ranged from dry with burning heat in the centre of the continent to monsoon rains along the coasts. But it did not have ice caps or flowering plants.
Life in the Triassic period had a difficult start. In the Permian period, just before, the largest extinction of animals in Earth's history had just taken place.
But life recovered during the Triassic period. New species evolved and grew. This was the first time the dinosaurs appeared. The Permian period had wiped out the mammals that could have been competitors for these reptiles on land and in water.
One example of these mammals was the Dimetrodon, which had a large, sail-like shape on its back.
Land, sea and sky
Some of the reptiles living on land evolved into dinosaurs during the Triassic period. At first, these creatures were much smaller, but they eventually outgrew other animals such as the Lystrosaurus, a dog-sized animal that looked like a cross between a pig and a lizard.
These land reptiles thrived during the Jurassic and Cretaceous periods after the Triassic, and they ruled Earth's landscape for 165 million years. Some dinosaurs, like the Tyrannosaurus rex, became the top predators on land.
In the ocean, marine reptiles such as the plesiosaurs were kings. Plesiosaurus, an early plesiosaur, was about 4 metres long with a broad, flat body and a short tail. Plesiosaurs appeared in the late Triassic period, about 203 million years ago, and ruled the oceans for millions of years. One of these marine reptiles, Elasmosaurus, evolved to be about 13 metres long.
The Triassic period also saw reptiles take to the skies. Pterosaurs were the first vertebrates that evolved to fly.
The end comes
Most scientists believe the Triassic period ended when Pangaea started to break apart. This caused huge volcanic eruptions, and that was the end for many of these magnificent animals.
A new palaeontology gallery will open at the Hong Kong Science Museum this year. Visit it to find out more about these mighty ancient creatures!
Fun facts
Plesiosaurs were reptiles, but they were not dinosaurs. They did not have the legs that all dinosaurs had to walk on land. Instead, plesio-saurs had flippers that they used to paddle through the water.
Quick questions
- What major event happened during the Permian period?
- Which reptiles could fly?
- Why do you think Pangaea broke apart?
