are the most diverse group of vertebrates on Earth, with over —more than all mammals, birds, reptiles, and amphibians combined. Beyond being simple aquatic creatures, they are intelligent beings capable of using tools, recognizing human faces, and forming complex social cooperative relationships. The Evolution of Fish
The history of fish stretches back over to the Cambrian explosion. are the most diverse group of vertebrates on
: 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. with over —more than all mammals