The Earliest fish appeared throughout the Cambrian as small filter feeders; they continued to evolve throughout the Paleozoic, diversifying into many varieties. The earliest fish with devoted respiratory gills and paired fins, the ostracoderms, had hefty bony plates that served as protective exoskeletons against invertebrate predators. To make use of https://maps.app.goo.gl/kTisAZCbSjAw6nkX8