What are Modern Cetaceans?
As mentioned above, “cetaceans” is an all-inclusive term for whales, dolphins, and porpoises. There are two living subgroups (and one extinct, as will be explained below): odontoceti (toothed whales, dolphins, and porpoises) and mysticeti (baleen whales). All cetaceans but four species of freshwater dolphins are marine – they live in salt water. When looking at skeletons of cetaceans, it’s clear that fins and flukes were once limbs that were better adapted to movement on land. While modern cetaceans no longer have hindlimbs, their pectoral fins are modified forelimbs. Instead of depending on sight and smell for perceiving their environments, cetaceans rely on their sense of echolocation, or a super-heightened sense of sound. Where did Cetaceans Come From? Though there are many arguments regarding the true ancestors of modern cetaceans, many paleontologists agree that whales and dolphins evolved from a hoofed, land-dwelling mammal. Some argue in favor of a more dog-like ancestor, but it
