The origin and extinction of dinosaurs

The origin of dinosaurs can be traced back to the late Triassic period, about 230 million years ago. The earliest dinosaurs were relatively small and had relatively simple body structures, but they had typical reptilian features such as forelimbs and hind limbs, and had begun to differentiate into different species. Over time, dinosaurs gradually evolved into more complex forms, including some giant dinosaurs such as sauropods and theropods.

The extinction of dinosaurs occurred at the end of the Cretaceous period, about 65 million years ago. The cause of the extinction is still controversial, but several theories are widely recognized:

1. Massive volcanic eruptions: At the end of the Cretaceous period, continuous volcanic eruptions occurred on the earth, releasing large amounts of carbon dioxide, sulfur and other toxic gases, causing drastic changes in the global climate and bringing great pressure to many organisms.

2. Rising sea levels: As Antarctica and South America moved toward the South Pole, the Antarctic ice sheet was formed, and the sea level rose rapidly, leading to drastic changes in the marine environment. Many organisms could not adapt to this change and became extinct.

3. Undersea impact events: Some scientists believe that at the end of the Cretaceous period, an asteroid with a diameter of about 10 kilometers hit the earth, causing huge explosions and volcanic eruptions, changing the global climate and environment, and leading to the extinction of dinosaurs.

In short, although dinosaurs have been extinct for billions of years, they are still an important research object for us to understand the history of the earth and the evolution of life.

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