The Cenozoic followed the Mesozoic Era. These soft-bodied invertebrates include animals like squid, octopuses and cuttlefish. They move with by squirting water through a siphon, a type of jet propulsion. Many also squirt ink to help escape predators. There are 75 species of whales, dolphins, and porpoises.
Male chimaera are smaller than the females.
They lack true bone and have skeletons composed of cartilage. Because of this they do not fossilize well. They have a hollow nerve cord that ends in a brain. The dorsal fin is small and closer to its tail than on most sharks. The large eyes have green pupils.