Why Do Whales Have A Divergent Evolution?

Based on the evolutionary pattern of whales and dolphins, we can see that they are of divergent evolution; in which a trait held by a common ancestor evolves into different variations over time. This report will endeavour to prove that theory, and explain why whales and dolphins have a divergent evolution.

Whales and dolphins are often called cetaceans when referring to both species. The cetaceans are a marine mammal, descendants of land mammals. A cetacean is an aquatic species that needs air from the surface, the bones of their fins resemble the limbs of land mammals and the vertical movement of their spines is a characteristic for a running land animal than a horizontal movement of fish.

Evolution

The cetacean evolution has one of the most

The ancestors of modern-day whales and dolphins is said to have entered the water roughly 55 million years ago, in the Eocene epoch. Both species relate to the Indohyus, an extinct semi-aquatic deer-like ungulate, from which they split approximately 54 million years ago. These primitive cetaceans first took to the sea approximately 50 million years ago and became fully aquatic 5 – 10 million years later.

Although they are not the ancestors of whales, on this evogram we notice that hippos are the closest living relatives of whales. None of the individual animals on this evogram are the direct ancestor of any other, as far as discoveries show. That is also why each different animal gets its own branch on this family tree.

Like whales, hippos are large and aquatic, the two groups evolved these features separately from each other. We know this because the ancient relatives of hippos called anthracotheres were not large or aquatic. Nor were the ancient relatives of whales that you see pictured on this tree – such as

The front limbs of a whale are called flippers. These flippers look like paddles and will vary in size depending on the species of whale. A whale’s flippers move back and forth as they glide through the water. Beneath a whales skin their lies a layer of fat called blubber, which insulates the body and stores energy. A spinal column, a vestigial pelvic bone, and a four-chambered heart are all things a whale possesses. Typically their neck vertebrates are fused, an adaptation that trades flexibility for stability during