Arandaspis

Arandaspis prionotolepis is an extinct species of jawless fish that lived in the Ordovician period, about 480 to 470 million years ago. It is the oldest known vertebrate.

Its remains were found in Alice Springs, Australia in 1959, but it was not discovered that they were the oldest known vertebrates until the late 1960s. Arandaspis is named after a local Aboriginal tribe, the Aranda (currently called Arrernte).

Arandaspis was about 15 cm long, with a stream-lined body covered in rows of knobbly armoured scutes. The front of the body and the head were protected by hard plates with openings for the eyes, nostrils and gills. Although it had no jaws, Arandaspis might have had some moveable plates in its mouth, serving as lips, sucking in food particles. The low position of its mouth suggests Arandaspis foraged the ocean floor. It had no fins; its only method of propulsion was its horizontally flattened tail. As a result, it probably swam in a fashion similar to a modern tadpole.