The Earliest fish appeared in the course of the Cambrian as compact filter feeders; they continued to evolve through the Paleozoic, diversifying into many kinds. The earliest fish with devoted respiratory gills and paired fins, the ostracoderms, had weighty bony plates that served as protective exoskeletons towards invertebrate predators. There https://maps.app.goo.gl/kTisAZCbSjAw6nkX8