evolution  of the dolphin

Evolution of the dolphin.

Dolphins, along with whales and porpoises, are descendants of terrestrial mammals,Artiodactyla more precisely. The Modern dolphin skeletons have two small bones in thepelvis, indicating that once had hind legs.

First he had fully terrestrial form about 50 million years, therefore, takes place duringTertiary laer. The amphibious form was reached after five million years, and many morewere needed for the formation of the characteristic horizontal tail fin. The successivetransformations occurred in the direction of strengthening their expertise, and refer to the increase in brain mass and the birth of an elongated shape of the snout, with teethdifferently.

Ancestors of the dolphin.

These are the ancestors of the current Dolphin:Mesonychidae.Protocetidae.Dorudontidae.Squalodontidae.Delphinidae.

Mesonychidae.

Eocene terrestrial ancestors (fourth stage of the Tertiary period) that lived about 50 million years.

Protocetidae.The first known aquatic form, probably amphibian that lived about 45 million years.

Dorudontidae.

Completely aquatic some 40 million years.

Squalodontidae.

The appearance is similar to the dolphin in the Oligocene (third stage of the Tertiary period), about 25 million years

The modern dolphins, with the bottle-shaped nose, make their appearance about 15 million years.

Delphinidae.