: The Devonian period (roughly 419–359 million years ago) saw a massive explosion in fish diversity, including armored placoderms and the first ancestors of modern sharks and bony fish.
The history of fish stretches back over to the Cambrian explosion. : The Devonian period (roughly 419–359 million years
: Critical evolutionary steps included the shift of gills from filter-feeding to oxygen absorption, and the development of the jaw, which transformed fish into active predators. Major Biological Groups 11 Fun facts about fish - BC SPCA and the development of the jaw