INDICATORS ON ANIMALES YOU SHOULD KNOW

Many animal phyla 1st appear from the fossil history during the Cambrian explosion, commencing about 539 million years back, in beds like the Burgess shale.[96] Extant phyla in these rocks include molluscs, brachiopods, onychophorans, tardigrades, arthropods, echinoderms and hemichordates, along with many now-extinct types like the predatory Anomal