Barramunda / Australian lungfish
(Neoceratodus forsteri) in the Frankfurt Zoological Garden.

There are 6 species of lungfish in the world, of which the Australian is the most primitive. The lungfish morphology has hardly changed in the last 100 million years and therefore, like the closely related coelacanths, are considered living fossils.

Genetic studies, as well as the skull structure, the arrangement and shape of the fins, the approach of separation of oxygen-rich blood from the lungs and oxygen-poor blood from the body, suggest a close relationship to the tetrapods, to which we also belong.

Netherless, the lungfish aren't considered our ancestors, but are closely related to them.