Most would find animal life in the sea, and of course, we would not find, orcas, whales or sharks, or even, similar animals. Arthropods and vertebrates ruled the prehistoric seas and began to emphasize vertebrate species timidly, promised much for its featuresin particular the spine.
One of the first was the Arandaspis marine arthropods, one of the first fish that descended from Pikaia and that would lead to the wide range of armored fish as Dunkleosteus.
This aquatic fish, just have information. It was found some 60 years ago in Alice Spings, Australia and its name comes from the tribe that inhabited those lands (Aranda). It was about 15 cm and started having bony plates on the body that gave some protection, began to form the shield would then armoured prehistoric fish.
These fish were small, and a feature of them was that they had jaw (some experts think they did have), only a small, hard lips that helped him to swallow everything that was while prospecting in search of food. In our view, it would seem a tadpole, but bigger and harder. Anyway, as I introduce you to one of the first vertebrates to have lived on Earth and apparently, succeeded because it appeared a large number of new species.