( Note: I asked this question and guess who the first person to answer it was? Gerald fucking Mcdonald. )
Q:What would dolphins look like if they went back to land again? Would they become bipedal and have hands with opposable thumbs, or would they have hooves like their ancestors?
A:They were never land lubbers. They as well as any other water loving mammal, have always been living in water. Their ancestors were created in water. And this is how they have always been..
12 comments
Come on man, how do you not have anything better to do? First answer i get to my question is by GERALD MCDONALD of all people!?!? And also Gerald, you… might wanna check the fossil record. The ancestors of dolphins lived on land. They share a common ancestor with hippos and I think something like that would be obvious considering the fact that DNA tests have shown that they are related to even-toed ungulates. Now quit browsing Quora all day just to dismiss peoples hard work and scientific studies, okay?
Q:What would dolphins look like if they went back to land again? Would they become bipedal and have hands with opposable thumbs, or would they have hooves like their ancestors?
Neither. Evolution is irreversible: once lost, adaptions can only evolve anew convergently. Indeed, whales are themselves excellent examples of this principle.
Ceteceans have all but completely lost their lower extremities, with the only vestiges being a few small penis bones disconnected from the rest of the skeleton in males that serve to anchor the penis. As such, we can dismiss the possibility of whales returning to a tetrapodal body shape.
Evolving into humanoids is even more implausible - far more so, in fact - as it would not only require the above, but that those new hindlimbs would become the sole mean of locomotion. Plus, dolphins would have no need for opposable thumbs as they already have a manipulatory organ that serves them just fine - their snouts. Humans, meanwhile, have opposable thumbs because they are secondarily ground-dwelling arboreals whose ancestral mode of locomotion is quadrupedal prehensive climbing (and who lost the prehensible capabilities of their feet as part of their adaptions to permanent erect gait). Really, the idea that sapient creatures would converge into humanoids is nothing but an anthropocentric fantasy of humans as a perfect lifeform, it is long discredited and needs to die.
If ceteceans would ever return to the land, their locomotion would probably restricted to something akin of that of a earless seal.
Addenda/Errata:
Actually, whales with hind flippers still occur as an atavism - a “throwback” where “lost” traits are expresed again - usually because the structures are still formed during embryogenesis, but are resorbed prenatally, which include the hind limb buds of whales -, and it is possible for an atavism to become adaptive and thus established (e.g. the wing claws of juvenile hoatzins and turagos used for climbing), so I would correct myself that whales becoming tetrapodal again is not strictly impossible, but still extremely unlikely.
It may be noted that, while I have been unable to find anything on whales expressing hooves atavistically, the other group of fully aquatic mammals, the elephant–related Sirenians (sea-cows), more specifically the manatees, do have vestigal hooves.image
@Bastethotep #81927
You are right that atavistic rear flippers sometimes occur in dolphins - but as far as I know it is usually just "exterior tissue" without any skeletal structures, which makes a "readaption" even more unlikely, if not impossible.
@anonymous-165519860 #81904
Therre are some species which have evolved and lost traits multiple times as conditions change.
It's as with the rest of evolution, something you have is adapts to new opportunities.
So, nothing would revert, exactly, but something may change going forward. Their flippers may become lefs, or they may have a reason to retain flippers and instead grow land-moving appendages from something else. Maybe the tail becomes like a skink's to propel them over swampy ground, retaing flippers to maneuver in the water....
Confused?
So were we! You can find all of this, and more, on Fundies Say the Darndest Things!
To post a comment, you'll need to Sign in or Register . Making an account also allows you to claim credit for submitting quotes, and to vote on quotes and comments. You don't even need to give us your email address.