What do you know about dinosaurs?

Dinosaurs belong to vertebrate reptiles. In ancient times, about 570 million to 248 million years ago, soft boneless creatures evolved into fish with bones in their bodies. Fish gave birth to amphibians that walked on land and then evolved into reptiles.

One of the reptiles evolved into a primitive dragon. The earliest dinosaurs appeared about 240 million years ago. They were once found in Mesozoic land swamps, with long necks and middle tails, hind limbs longer than forelimbs, tails and the ability to walk upright.

2. The development of dinosaurs

The early semi-aquatic type of Chulong has a reliable genetic relationship with dinosaurs, such as Zhilong, the representative of Chulong. But later, because the weather became drier and drier, the dinosaurs in the water could not help but come to the shore. On shore, because their forelimbs are short and their hind legs are long, they limp and walk on their hind legs instead. With the change of posture, the movement speed becomes faster, which is a key step in the evolution of dinosaurs.

But at that time, because the physical condition was not perfect, it was not suitable for life on land, and most of the rest of the time was spent in the water. Once the body structure is more perfect, real dinosaurs will appear. It is said that the ancestor of dinosaurs was a small early dragon named "pike crocodile", which was about 60- 100 cm long. It evolved from an earlier semi-aquatic animal, dragging its heavy tail and being long. Over time, pike evolved into a dinosaur.

3. The extinction of dinosaurs

Scientists found that the content of trace element iridium in the clay layer of the late Cretaceous stratum suddenly increased by 30- 160 times compared with other periods. Iridium is a rare element in the earth's crust but widely exists in asteroids.

Therefore, at present, the most popular and influential view is that 65 million years ago, a meteorite hit the earth, filling the sky with dust, leading to drastic climate change, a large number of plants died, and dinosaurs were devastated by lack of food. In fact, there are many explanations and statements about the mystery of dinosaur extinction, including 100.

The living habits of dinosaurs

1, feeding

The plants that herbivorous dinosaurs can eat are highly restricted, so some small herbivorous dinosaurs will stand on their hind legs in order to eat the leaves of tall plants. Carnivorous dinosaurs ate herbivorous dinosaurs and other animals. Various dinosaurs' different ways of foraging will also be reflected in their teeth.

2, struggle

Sharp teeth and claws are hunting weapons for carnivorous dinosaurs. Tyrannosaurus rex would look for individual herbivorous dinosaurs, so they often acted alone. And some dinosaurs will act in groups, lock in their prey and flock to them, and cut their prey's abdomen with their claws on the second toe.