Paul D. Taylor

“Fishes are the most primitive vertebrates (animals with backbones). They are a very varied group, with about 20,000 species, and they use gills to breathe and fins to swim. Some fishes live in the sea and some in fresh water; others migrate between these environments. Fishes first appeared about 500 million years ago. Most were small, jawless, and covered with heavy armor. In the Devonian period, often referred to as the Age of Fishes, fishes became numerous, and early representatives of the major living groups were present. Skeletons of fossil fishes can be abundant in certain areas, but it is more common to find isolated teeth, especially of sharks.”
― Paul D. Taylor, Fossil