Myllokunmingia

Myllokunmingia

All known vertebrates can trace their ancestry back to Myllokunmingia, which is thought to be the first animal with vertebrae. This creature is a primitive example of a fish. These fish are thought to have an advantage over other life (invertebrates) due to increased mobility and non-brittle armour. They eventually evolved into amphibians, which had the ability to go onto land, but had to stay near water. These amphibians evolved into reptiles, which were not confined to stay near water all the time as the amphibians were. These reptiles evolved into dinosaurs, mammals and birds.

-Darwin