The evolutionary order of vertebrates is roughly as follows:
1. Fish: Early vertebrates were all aquatic organisms, and the first vertebrates to appear were fish, about 500 million years ago.
2. Amphibians: About 350 million years ago, some fish adapted to the terrestrial environment through evolution and evolved into amphibians, that is, animals that can live in water and on land.
3. Reptiles: About 300 million years ago, reptiles began to appear. Their body structure is more suitable for terrestrial life, such as having limbs for support, and the skin is covered with stratum corneum to protect themselves from dryness, ultraviolet rays, etc.
4. Birds: About 150 million years ago, some dinosaurs evolved into birds. Their forelimbs became wings, allowing them to fly.
5. Mammals: Mammals first appeared about 220 million years ago, but the real diversity of mammal species appeared 65 million years ago. Mammals are characterized by producing milk to feed their young and having hair to keep their body temperature and protect their skin.
In general, this evolutionary order is a rough description and does not mean that the appearance of these animals is completely linear. Different types of vertebrates may exist at the same time or influence each other at various times and environments.
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