Dinosaurs are a diverse group of dominant vertebrates in Mesozoic, most of which belong to terrestrial reptiles. It is said that it is a vertebrate, not a reptile, because dinosaurs were once classified as reptiles, but it does not conform to one of the basic characteristics of reptiles: the crawling way of walking and the cold-blooded animals that have been questioned.

Dinosaurs once ruled the global terrestrial ecosystem for more than 65.438+0.6 billion years. Dinosaurs first appeared in the Triassic period 230 million years ago and died out in the late Cretaceous period about 65 million years ago. ? Dinosaur, the English word dinosaur, comes from the Greek deinos (meaning terror) Saurosc (meaning lizard or reptile). Dinosaurs (excluding birds) are a group of main dragon reptiles living on land. Their limbs stand upright under their bodies instead of extending to their sides. They appeared in the late Triassic Carney period, and various dinosaurs quickly evolved into different specialized features, and showed different body shapes, occupying different Tibetan dragon niches, and continued to exist in the late Cretaceous Maastricht period.

Dinosaur (Latin name: Dinosauria) is a diversified dominant terrestrial vertebrate in Mesozoic, which ruled the global terrestrial ecosystem for more than1600,000 years. Dinosaurs first appeared in the Triassic period 230 million years ago and died out in the late Cretaceous period about 65 million years ago.

Animals that developed and evolved in the early days of the earth, such as Jurassic dinosaurs and trilobites, were mostly extinct due to evolution or climate change. Now, we can only see the evidence of these animals through fossils. However, platypus, crocodiles and other animals have adapted to the changes in the natural environment and survived in the long evolution.