The Pikaia beings is one of the most important and that we should highlight, if we get an overall idea of the exciting topic of evolution and prehistoric animals, I mean ...
Cambrian, 540 million years ago, at the beginning of the explosion of life that happened and all the various forms that appeared in the ancient seas. Appears then a small might just measuring 2 in (5 cm) long. We're talking Pikaia.
This little creature would become the source of one of the major groups of animals to would be more successful throughout the history of Earth and ... where we also are included: vertebrates.
Lions, hyenas, falcons, whales, sharks, Allosaurus, Triceratops, Sabertooth, armored fish, gorillas and we owe our existence to this small, first vertebrate. We all come from it and was its advantageous morphology characteristic of vertebrates, which helped them survive, although it was a small animal compared to others of his time.
Well, Pikaia was not a colossus or an apex predator in fact measured about 2 in (5 cm) long.
His body was flattened, hydrodynamic, which used to navigate near the ground where it fed, probably, filtering water particles.
Most characteristic of this small, prehistoric fish was that, unlike molluscs, which are invertebrates and some shelled, and arthropods with exoskeletons, the pikaia possessed the notochord, which is considered the evolutionary precursor of the column spine in all vertebrates.
This feature provided a fast, elasticity, speed with no other animals. Thanks to this feature, so it survived and was able to escape predators. Because the evolutionary experiment went well and that the Pikaia survived ... we are here.