The 'Missing Link' of Dolphins.

We all know the theory about dolphins. At some point in time, their ancestor's left the ocean, only to return later, and evolve into the modern dolphin.
Well the discovery of a dolphin with extra limbs may point to support this theory.

Japanese researchers said Sunday that a bottlenose dolphin captured last month has an extra set of fins that could be the remains of hind legs, a discovery that may provide further evidence that ocean-dwelling mammals once lived on land.

edition.cnn.com...

interesting find. However, it could just be a birth defect or something, ive been fishing and caught fish with more fins than normal, and i just figured that it was born with it, kinda like how some people are born with 12 fingers

I don't think this is really a "missing link" just some type of throwback or defect.

It is not disputed that dolphins and whales are mammals and therefore must have evolved from a land mammal, but I think it's still unresolved exactly what they evolved from. The latest DNA surveys I think do indicate the animal most related to them is the hippopotamus, but for years beforehand they were thought to have evolved from a group of now extinct wolflike hooved creatures from the fossil evidence.



[edit on 11/6/2006 by djohnsto77]

I probably shouldn't argue with the experts, but couldn't this just as easily be one of those random adaptations to the environment that might or might not become predominant in the species, if the mutation offers an advantage?

Now, a dolphin with a hind foot would really get my attention.

Yeah, they did say that it may just be a mutation. Even if it is, it's still another step closer to finding out more about the species.

A freak mutation may have caused the ancient trait to reassert itself, Osumi said. The dolphin will be kept at the Taiji museum to undergo X-ray and DNA tests, according to Hayashi.

Originally posted by djohnsto77
The latest DNA surveys I think do indicate the animal most related to them is the hippopotamus

Hmm. That is news. Last I heard is that they have evolved from the ancestors of cows, but it was about two or three years ago that I heard that. Hippos do seem more likely though.

You guys don't seem to realise, that this shows how easily evolution happens. It probably has a genetic disorder, which gives it a second set of genes (Or at least some of them), that corrsponds to its front limbs.

Ancient hippo-> manitee (or something resembling it)-> Pilot whale (or something resembling it) -> dolphins.

Dolphins are awasome.

I work with farmed salmon and various other kinds of fish, and it's not that uncommon to find them with mutated fins. The dorsal fin especially seems to mutate the most, often just being a stump of bone below the skin rather than an actual fin.

I don't think it is an "evolutionary throwback". You have to remember that all living creatures are mutating all the time. Whether you have messed up cells in your body, or some kind of deformity, everyone has small mutations occuring day-to-day. Evolution is just these mutations making the animals better off, so their genes get passed on and the mutation becomes more common. If dolphins are more efficient with four fins instead of two, the number of four-finned ones will continue to grow until there are no two-finned ones left.

So because this dolphin has an extra set of fins it is some evolutionary throwback?

Then I guess this picture is proof that man decscended from a race of 3 legged cave men.




He was obviously an evoultionary throwback too,
These a both examples of deformities.

Lord have mercy... some of the stuff you read here.

If ATS doesnt open ones mind... aint a key in the world that will.

How do two extra, stubby fins prove that dolphins lived on land? Isn't the fact that they're air-breathing, mammals enough? I never knew that it was theory that dolphins evolved from animals that came out of the oceans to live on land and then returned later. I always assumed that was fact.

What's the other side of the argument as to why these mammals, along with whales, live in water?

Like the rest, I'm not convinced of it as an evolutionary throwback. Or forward step, either.

Oy.

Lately there's been a lot of the "ooo! Devolution" from scientists who should know better. We've got a very nice timeline of dolphin evolution, and changes in the flippers (as so many have said) do NOT mean the thing has evolved or deevolved.

Oy. Mutation, yes. Previous form, no.

Are there any records of animals "de-evolving"? I know that all evolution is a forward, but has there ever ben a case of an evolutionary throwback becoming the standard for a species?