Does anyone else think that Pinniped's (seals, sea lions etc) are half way to evolving into Dolphins?

Question

If you think that dolphins and whales must have looked like animals that lived in and out of the water at some stage in their evolution, with half formed flippers and tails - don't you think in 25 odd million years the pinniped's will resemble whales and dolphins?

Answer 1

It's entirely possible, although you might consider evolutionary pressure driving the transition from semi-aquatic to entirely aquatic living. Seals still need dry land to give birth and raise pups, which is why the youngsters are born with fur. You'll notice that dolphins and other cetaceans no longer have fur, but it's entirely possible the semi-aquatic creatures they evolved from did. Seals are so well-adapted for sea life that most species lose their fur in adulthood as they no longer require it.

On the other hand, if selection drives it, it is also possible that seals could become predominantly land-based animals, spending less time (evolutionarily speaking) in the water.

Answer 2

"Seals are so well-adapted for sea life that most species lose their fur in adulthood as they no longer require it."

Not so. All seals and sea lions have fur or hair throughout their lives. Seals will moult their skin each year but new hair grows in the new skin.

There are already two distinct groups of pinnipeds, the eared seals (fur seals and sea lions) and the true seals. There are distinct differences betwen them. There are two distinct groups of whales, the toothed whales including dolphins and sperm whales and the baleen whales.

Evolution has no direction so it is impossible to predict that a particular animal will evolve in a particular way. I would expect the differences between the two groups of seals to become more marked and it is possible that they could become more aquatic, giving birth in water rather than on land but no-one can be sure.