Saw some program recently that mentioned that dolphins and whales are examples of animals that moved from land to water during their evolution. Makes sense, since it is believed to have been fish getting amphibious, giving way to reptiles which then became birds which then became mammals. There are plenty of mammals that spend much of their lives in water, but not many that spend their entire lives underwater. So... what common ancestors do dolphins or whales have on land? The closest relatives I can think of are maybe seals or walruses. If not their ancestors, then what kinda mammals split off and took to an entirely underwater life?

Yeah, I can Google this. I just thought I'd try here first, in case somebody might already know the answer or have a better guess than what I can come up with.

PS, blue whales can be up to 200 tons

scott wrote:Saw some program recently that mentioned that dolphins and whales are examples of animals that moved from land to water during their evolution. Makes sense, since it is believed to have been fish getting amphibious, giving way to reptiles which then became birds which then became mammals. If not their ancestors, then what kinda mammals split off and took to an entirely underwater life?

.

Its not really how evolution works. BIrds don't 'become' mammals. A bird is a bird for its entire life.

Every species that exists now, is the most "new" type of that species. People see alligators and marvel at how they look like dinosaurs, when they dont, they look like modern day alligators.

In other words there isn't a "pre-dolphin/whale" walking around in Australia. Not to mention evolutionary history is full of holes and guesswork due to a fragmented fossil record.

In general the "pre-whale" i guess could be a Hippo, but not really. Their shared ancestor is so many millions of years ago that its really not a single species they split off from, but more of a "type". Instead of 1 dead on species (although I am not certain of that)

Finding a break point for a species in the fossil record is a relatively rare and groundbreaking event. The human/ape "missing link" has been found, debunked, refound etc...

Thats the main problem w/ evolution. Its complicated and incomplete. This causes most people who don't bother studying it ever to simply reject it as "just a theory" and no one has a good counter argument to that yet. Even tho the "just a theory" argument simply demonstrates ignorance for scientific terminology.

Back in highschool/gradeschool, we learned that whales came from a species related to the cow. However, recent studies have shown it to come from an ancient creature that resembled much of a wolf. The skull of this creature is very close to that of a whale.

These are illustrated reconstructions of what that animal might have looked like:



Pakicetus

Looks more like a giant rodent than a wolf.

Here's the evolution of the skull, particularly the nasal:

Hexpane wrote:Thats the main problem w/ evolution. Its complicated and incomplete. This causes most people who don't bother studying it ever to simply reject it as "just a theory" and no one has a good counter argument to that yet. Even tho the "just a theory" argument simply demonstrates ignorance for scientific terminology.

I'd like to hear more of this please. Your thoughts/links.

As far as evolution goes I'm sceptical. I don't know if this scepticism is due to the patchwork reading I have done on the subject, or that emotional part of me that really wants to reject it.

This one looks more bad ass and is an early cousin of whales:


Ambulocetus natans

scott wrote: seals or walri.

fyp.

I didn't mean to suggest that one morning a snake wakes up and has become an eagle. I don't think I've ever even heard of a person misunderstanding evolution that poorly, though I'm sure it happens.

I also realize it's not like "okay hippo, now some of you will no longer be hippo, now you'll be whales" or anything like that. maybe some hippo-like animal some hundreds of millions of years ago mutated over the course of time to move its nose to the back of its neck or back or wherever a blowhole is located, and took to a life in the water. since they breed and birth in the water, it obviously would have had to be multiple animals making this move at the same time, abandoning the land. maybe there were hundreds or whatever, who knows. and then being in the water allowed this animal to increase in size (over eons, of course) to be 25 times heavier than land-based hippos.

It's pretty astounding to me.

Hexpane wrote:Its not really how evolution works. BIrds don't 'become' mammals. A bird is a bird for its entire life.

The Kiwi of Australia has mammal like traits, so, over millions of years, a bird can certainly take on traits of a different species based on it's enviornment.

Of course a bird is a bird for IT'S entire life. But, they have evolved from some form of life other than a bird. A bird didn't just (poof!) appear one day.

how about the super-long gestation period of whales, too. 1000 generations can be just a handful of years for tiny shit like insects or whatever. How long does it take a whale to grow from birth to reproductive adult and then gestate a baby? their evolution would take gazillions of years for even small changes, right?