Sturgeons are considered to be among the most primitive bony fishes, with origins dating back 120 million years.

This also remains a significant element of the jaw in some primitive bony fish, such as sturgeons.

The organ is active in adult forms of some primitive fish, like lampreys or hagfish.

Its appearance is similar to a "primitive fish".

In the Devonian period, Arizona was home to primitive fishes.

A primitive fish also has a little swelling at the front end of the spinal cord, which is its brain.

It was a heavily armored primitive fish from the Late Devonian period, living about 360 million years ago.

They are primitive fish; sturgeon fossils 200 million years old have been uncovered.

The head of the trilobite was a gristly primitive fish.

The fossils are of primitive fish and date back 450 million years to the Ordovician Period.