Did you know the first land animals lived 450 million years ago?
Arthropods were one of the first land animals. They had hard outer bodies and jointed legs. Prehistoric insects, spiders, and millipedes are examples of arthropods. Gerrothorax is another land animal from long ago that used be in the water. It was a fierce hunter. When it saw a fish, it jumped out of the water and ate it. Then there was Acanthostega, which was the first four-legged land animal. It lived 380 million years ago. It grew up to three feet long and walked on land too.
Four-legged animals are called amphibians. They were the first animals that ran on land. Aphaneramma, which was an amphibian, had very long legs and could run very fast. Eogyrinus, another amphibian, was very big, almost 16 feet long. It had a dangerous jaw and teeth. Eogyrinus was often in water even though it could walk on dry land.
When water animals became land animals, their fins turned into legs. For example, the ichthyostega had a big tail with a fin. The tail and fin helped the animal swim, but they also became legs that helped for walking on land.
Long ago, many water animals became land animals. They are all different but had a similar transformation.
[Source: 100 Things You Should Know About Prehistoric Life]