Did We Have "Reptilian" Ancestors?

Science

(Blogging Graduate Student) #81

The pelvis functions in reproduction. Those leg bones in the image are a rare atavism, not a “design feature”. It means that whales still retain developmental potential to produce hind limbs from their legged ancestors.

This is also evident in embryos: Fetal whales have hindlimb buds – Evolution For Skeptics


(Mikkel R.) #82

Somehow most whales make do without them. No, they really are vestigial legs. You are probably thinking of the small rudimentary pelvis remnant. This is a humpback whale born with actual legs potruding from the body (look at the pictures), in the location where you expect it’s ancestor to have had legs, complete with the bony articulations expected of actual legs (femur, tibia etc.), attached to the rudimentary pelvis via muscles and sinew, like you’d expect of actual legs. In every way you’d expect them to be legs, they qualify as legs. They were legs.

Why would whales carry around degraded genetic pathways for the development of legs if they did not actually evolve from legged ancestors? They wouldn’t, so they carry those genes around in their degraded form exactly because they have inherited them from ancestors that really did, once upon a time, grow fully functioning legs.


(Greg) #83

Sorry. It was USC that made these conclusions:

If one was to conclude that whales did indeed change from land dwelling animals to sea farring ones, this process is so complex that happening across mutations in such perfect order without intelligence seems quite unrealistic to me. Could God in His infinite wisdom and control choose to alter a land dwelling animal to a whale? I have to conclude that i am not God and He did and does what He wants in the ways He chooses, so i will place my hand over my mouth.


(Mikkel R.) #84

So you’re going for the “God works in mysterious ways, and really would decide to put legs on a whale just to test our faith”.

With that attitude, you have made it impossible for evidence to ever convince you otherwise. In so far as evidence that contradicts your belief is found, you will rationalize that evidence has having been planted, by God, to give a deceptive impression of an event that didn’t actually occur.

I concede, I can not argue against such a position. It is utterly irrational, and no rational argument can defeat it.


(Greg) #85

As i have studied this topic for years, i have concluded that there is a level of mysteriousness that both the evolutionist side as well as the creationist side try to explain away to fit their particular positions to warrant a declaration that God is in control and is beyond us to a point that we need to all stop the bickering and revere Him. I am a Christian, and the Bible in dozens of places demands this very thing.

So i dont say this as a cop out, but as a declaration of truth.

Now for those of you with no faith in God (you are an atheist are you?) you will have to wrestle with how to truely make logic of the luck involved of the selection of mutations which are proven to be mostly neutral and many times detrimental to the organism and vast amounts of time leading to complexity and not extinction.

Im personally looking forward to reading Behe’s new book. Im sure i wont agree w everything because as you might notice, i believe that God created in a short amt of time not long ages like Behe does. But i know of principles in his book that clearly define that intelligence is necessary and if this is true, then perhaps the existence of God who is even outside of time will really scramble and confound man’s science. Im also looking forward to going to worship our Creator this morning so i and my wife better get going here and get the kiddos ready. Enjoy your day!


#86

how do you know that its a vestigial leg and not a vestigial flipper?


#87

i dont think that its a leg but a vestigial flipper. so it cant be evidence for a common descent.


(Mikkel R.) #88

You mean like this?

It is entirely possible that the hind limbs of ancestral whales passed through a flipper-like stage reminiscent of Sea Lions. Of course, flippers with bony articulations homologous to legs would still be evidence for common descent.

So now whales evolved from semiaquatic mammals with flipper-like hind limbs? That’s “half” the transition to the fully aquatic lifestyle of whales you basically conceded right there. I am genuinely surprised that you reveal such an open mind.


(John Harshman) #89

To put it another way: “‘Shut up’, he explained.”


#90

no. i talking about a regular flipper, like the regular front flippers that whale actually has.its possible that the whale ancestor had an extra pair of hind flippers. so in this case it will not be evidence for a common descent but for vestigial flippers.


(Timothy Horton) #91

You dodged the question again Gerg:

What prevents micro level changes from accumulating over time into macro level change?


(Timothy Horton) #92

Vestigial doesn’t mean useless. Vestigial means having been lost or degraded from the original function. There’s nothing in evolution which says a vestigial body part can’t acquire a secondary function.


(Timothy Horton) #93

The fossils of the earliest proto-whales had legs, not flippers. That is true not just for cetaceans (whales) but also for other marine mammals like the sirenia (manatees). Here is a picture of a 50 MYO ancestor to modern manatees, Pezosiren portelli. You can clearly see the hind legs and feet.


#94

but it was not a whale but a dog-like creature. so you need to assume that they evolved from each other. so this vestigial trait isnt evidence for a common descent.


(Timothy Horton) #95

No, based on comparative studies of all its anatomy what were found were early cetaceans, not early canines. Same for the Pezosiren portelli which except for the legs is almost the same in skull / body structure to extant manatees.


(Mikkel R.) #96

But the whale’s “regular” front flippers don’t have those bones found in the vestigial hind limb.
Humpback_Whale_Skeleton_Museum_of_Osteology

The bones found in the vestigial hindlimb of the whale are like the hindlimb bones in other mammals, even those with hind flippers like the Sea Lion pictured in my earlier post.

Also, have you ever wondered why the front limbs of whales have that pattern of bones, with one-two and then several individual “digits”?
homologous2

.its possible that the whale ancestor had an extra pair of hind flippers. so in this case it will not be evidence for a common descent but for vestigial flippers.

Your analysis is suspiciously superficial. Merely calling them “extra pair of hind flippers” does nothing to explain why they would even be there, nor the particular features they have.
Here I have compared them to the bones found in the hind leg of a cow:

I am certainly no comparative anatomist, but even to my untrained eye it doesn’t look like the bones of another pair of vestigial front flippers to me. And if they’re vestigial hind flippers, then they are clearly homologous to the hind flippers of a Sea Lion, and even homologous to actual legs.


(Bill Cole) #97

I considered it possible that you changed your opinion.

I don’t remember your paper supporting a specific confidence for common ancestry. I remember a comparison between phylogenetic trees and morphological trees.

Why? As I’ve said, the data are not available. You are of course free to sequence the genomes of a couple of dozen species, annotate them, and search for orthologs.

This data is available for other species and puts actual ancestry into doubt. I know you are aware of this and disagree it is a problem.

Based on your particular definition of common descent which only explains similarities I agree with you but it appears that common ancestry is a stronger claim then common descent.

Why is making a claim about what science cannot address not a scientific claim?


(John Harshman) #98

It’s impossible to take you seriously.

Your memory is flawed. Read again. Agreed, there is no explicit conclusion that crocodiles are all related, just as there is no explicit conclusion about how many beans make five. But strong support from the data for a particular tree, especially when many genes confirm the same result, is very good evidence of common descent.

Exactly. You understand nothing about that result; I believe you’re referring to “Sal’s flower”, right?

I have no idea what any of that means, but it’s clearly based on some deep misunderstanding. What’s the difference between common ancestry and common descent?

I suppose it depends on what the term means. I would say that a scientific claim must be something that science can address. “There’s an invisible, undetectable elephant in my living room” is not a scientific claim, for example. What do you think the term means?


(Timothy Horton) #99

I gave up trying to get scientific concepts through Bill’s neutronium noggin. As a wise man once said;

“Never mud wrestle with a pig. You just get all dirty, and the pig likes it.” :slightly_smiling_face:


#100

they are actually very similar. so its not different from a shark hind\front fins comparison.

here is your evidence:

https://scienceblogs.com/laelaps/2008/06/20/the-dolphin-with-extra-fins-2

so we do have evidence that a dolphin/whale had extra flippers in the past.