The Earliest fish appeared in the course of the Cambrian as compact filter feeders; they ongoing to evolve from the Paleozoic, diversifying into several forms. The earliest fish with focused respiratory gills and paired fins, the ostracoderms, experienced large bony plates that served as protective exoskeletons against invertebrate predators. Encyclopaedia https://maps.app.goo.gl/kTisAZCbSjAw6nkX8