Fish -

: 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.

: 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 : The Devonian period (roughly 419–359 million years

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 and the development of the jaw