text: what organisms spanned many periods of time? i need to: list 5 organisms that spanned many periods of time and 5 organisms that went extinct over periods of time cobra is pretty correct, but rhinoceroses haven't been around for very long, geolocigally.   go with "trilobites" instead, or turtles or sharks.  or even coelocanths.....that'd be a good one.  5 that went extinct are dodo bird, sabre-toothed tiger, brontosaurus, giant sloth, mastodon