Why did the dinosaurs escape the mass extinction at the end of the Triassic?

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2022-08-18 21:06:45

In Earth’s long geological history, there have been five mass extinction events. At the end of the Triassic about 200 million years ago, an unexpected disaster led to the extinction of a large number of terrestrial organisms.

However, the dinosaurs were lucky to escape this disaster and successfully “rise” to world domination in the Jurassic and subsequent Cretaceous.

So, what caused the mass extinction on land at the end of the Triassic? Why were dinosaurs able to survive the natural disaster of biological extinction and grow rapidly after the disaster?

On July 2, researcher Sha Jingeng and Dr. Fang Yanan from Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, in collaboration with American academics, published new research results on internationally renowned magazine “Science Advances”. This study talks about the main cause of the mass extinction of terrestrial organisms at the end of the Triassic period and how the dinosaurs escaped this event.

Biological Evolution of the Triassic

The Triassic is the first period of the Mesozoic era, which began 252 million years ago and ended 201 million years ago, lasting about 51 million years.

During the Permian before Triassic, the Earth had just experienced a tragic era for life. The mass extinction at the end of the Permian is known as the largest extinction event in Earth’s history. It took millions of years for the few remaining organisms to restore the Earth’s environment to a state suitable for most organisms.

However, the persistence of life is beyond imagination. After recovering and evolving after the mass extinction at the end of the Permian, Triassic organisms displayed a spectacle of flourishing, unprecedented growth of reptiles and gymnosperms.

The species of arthropods, dinosaurs, and mammal-like reptiles increased rapidly during the Triassic. By the end of the Triassic, dinosaurs were a diverse group of creatures, occupying an important position in the ecosystem, and the Triassic period is also known as the “dawn of the dinosaur age”. However, the dinosaurs at that time were still relatively weak and completely different from what we imagine.

At the end of the Triassic, a mass extinction event took place, the impact of this mass extinction is considered to be the weakest of the five mass extinctions, but there are still a large number of organisms on the planet. on land and at sea has gone forever. But it had a profound impact on the development of creatures in the Mesozoic, especially the golden age of dinosaurs.

Why did the dinosaurs escape the mass extinction at the end of the Triassic?  - Photo 2.

There have always been different explanations for the cause of the mass extinction event at the end of the Triassic, in recent years, researchers have increasingly focused on volcanic eruptions.

Scientists who support the volcanic eruption hypothesis believe that during the Early Mesozoic, the disintegration of the continent triggered intense volcanic activity, which increased atmospheric carbon dioxide concentrations and caused an effect greenhouse application.

The traditional view holds that the mass extinction at the end of the Triassic period of terrestrial life was due to global warming caused by large amounts of carbon dioxide released from volcanic eruptions, but life’s response on land after the extinction event seems to disprove this view.

The team surmised that the first supervolcano eruption brought about the volcanic winter. Volcanic winter refers to a large amount of volcanic ash and gas ejected by volcanoes, blocking solar radiation and causing the Earth’s surface temperature to plummet. And the cold is the cause of mass extinction.

Why did dinosaurs survive the disaster?

The team found dinosaur footprints and ice raft deposits at the same time in the Late Triassic to Early Jurassic sediments in the Junggar Basin.

Raft deposits are small sand or gravel (0.1-15 mm in diameter) floating in mudstone. Fang Yanan has two speculations about the deposition of ice rafts: one is that when the lake water on the shore freezes in winter, the gravel under the water also freezes. In the middle of the lake, it melts and settles in the mud; Another possibility is that in winter strong winds blow rocks from the ground onto the ice, and in spring the lake ice melts and gravel falls to the bottom of the lake.

“This shows that even during a period when the Earth had no glaciers at the poles, there was still seasonal freezing (subzero),” Fang said.

Why did the dinosaurs escape the mass extinction at the end of the Triassic?  - Photo 3.

The appearance of dinosaur footprints and polar ice raft deposits means that dinosaurs are very adaptable to the seasonal cold climate of the polar regions, and this is their “superpower” to survive. through the volcanic winter.

“Evidence of fossil feathers has been found in a number of herbivorous ornithischian dinosaurs. Based on phylogenetics, we infer that dinosaurs may have been born with feathers and that these feathers were very strong. could be used to retain heat,” added Fang Yanan, although all adult sauropod dinosaurs found so far have shown that they were hairless, it is possible that they were hairy at birth. and the hair sheds as it grows, like the African elephant.

Overall, the mass extinction at the end of the Triassic led to the extinction of a large number of animals and plants, but inadvertently opened a new door for the dinosaurs, dominating the Earth.

Reference: Zhihu

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