Creationist response to cetacean femur, leg atavism, and limb bud.

The desirability of such messages seems pretty dubious to me. To be considered further.Other admins welcome to also consider.There better not be any non-admin replies to this (my) message, within this topic.AdminnemooseusEdited by Adminnemooseus, : Fix typo: "withing" to "within". Added the "(my)".

---

Please be familiar with the various topics and other links in the "Essential Links", found in the top of the page menu. Amongst other things, this is where to find where to report various forum problems.

While we wait for GM, a few words about atavism. I should like to see more detail and quotations on this. In the meantime, a couple of thoughts:1.) If femurs reverted to an ancestral growing pattern, they would in fact grow outward not inward.2.) Growth is a self-coordinating process. Your freaky animals, for example, did not just produce extra bones. They got the muscles and tendons and nerves to match. It did not require a suite of mutations. How much easier would it be for tendon attachments not to develop during abnormal development?But I should really like to know more about this, and preferably from the horse's mouth rather than yours. What I've been able to find myself with an admittedly cursory look round doesn't seem to bear you out. E.g: The resemblances between your front and back flipper are the usual resemblances we find between forelimbs and hind limbs; the femur resembles the humerus; the fibula and tibia resemble the radius and ulna; and both have phalanges distally.But the differences are much more striking. My hindlimbs resemble my forelimbs much more closely than these flippers resemble each other. My hands and feet have the same number of digits, for one thing, and the same number of phalanges on the digits; and my feet have tarsals corresponding to the carpals in my hands, unlike this particular whale. But no-one would claim that I have hands on the ends of my legs despite this greater degree of similarity.Your hind and front flipper have less similarity than is usual in mammals, and you would have done well to keep quiet about it.We may also note that the digits in particular resemble the hind limbs of our old friend Dorudon. (Photograph here.)Your claim that they are actually forelimbs that have got into the wrong place is therefore unsubstantiated anatomically.Now let's consider their position. As your photographic freakshow demonstrates, the sort of anatomical abnormality you postulate can crop up anywhere on the body. Yet in cetaceans, time after time, these disputed atavistic hind limbs crop up exactly where hind limbs belong. Again and again, we see what look like the feet of primitive whales (which you claim are an extra pair of hands) attached to what look like a fibula and tibia (which you claim are a radius and ulna) attached to what looks like a femur (which you claim is an epipubic bone) which sprout at the same position at which whale embryos develop what look exactly like limb buds (which you claim are incipient mammary glands) and at the same position at which Dorudon had hind legs (which you claim are sexual claspers specially designed by God for that purpose). We do not equally commonly see these structures sprouting from elsewhere on whales, nor indeed do we equally commonly see hands sprouting out of the epipubic bones of kangaroos.Would not this observed regularity (if not explained in an evolutionary way) require either a massive series of coincidences, or for God to have weighted the dice in such a way as to delight evolutionists?And does not your explanation for all this seem somewhat strained compared to the straightforward evolutionary explanation? Everything has to conspire separately and in a piecemeal fashion to make it look like evolutionists are right. The whale, alone of all creatures, has to develop what look like limb buds but are in fact incipient mammary glands. The whale has epipubic bones, which most mammals get along without, and just happens to be prone to developing freak forelimbs attached to them which don't look like the forelimbs of whales. The best design for Dorudon's "sexual claspers" happen to look like limbs and be sited where hindlimbs are sited in basal mammals, and when whales develop freak extra forelimbs they just happen to always develop them in the same place ... and all this has to be arranged by a God whose intention is not to make evolutionists happy, but who made all these separate choices for perfectly good reasons whereof we know not ...... and on top of all that, it's not like this kind of thing is confined to whales.Edited by Dr Adequate, : No reason given.Edited by Dr Adequate, : No reason given.

I'm happy to discuss stuff, but I'm still working on the main paper - so I don't want to take too much time away from it until it is finished.I didn't go into all the detail I could have. I didn't say never fused (although I did say always separate - so my word choice could have been better). "Always" separate as in "humans always have two arms" - which could be contradicted by the occasional human born with 3 arms.There are cases of the femur fused to the pelvis in cetaceans, but this is an abnormality, not the normal case. This also highlights another departure from the typical quadruped pelvis. Typically, the pelvis ossifies at a different time frame than the femur, so you don't find cases of people with a femur fused to the pelvis.Just looking at pictures doesn't give you the whole "picture" - so yes, it seemed to me that the femur was just a bony nub attached to the pelvis - but now I realize that the fin pelvis we examined was an anomaly, and not the typical condition. The fused nub could very well be the femur in the fin example - or it could be a bone tumor - either way it is an anomaly.I'm certainly not saying that all cases of femurs are bone tumors. The cetacean femur connects to the pelvis with an acetabular like patch of cartilage. The pelvis might have a slight indentation, but a true acetabular cavity is a deep recess forming part of the ball and socket joint with the femur. This is certainly not the case in cetaceans and isn't really a debatable point. Papers both old and recent acknowledge that modern cetaceans don't have an acetabular cavity.The acetabular cavity is formed by different parts of the 3 main pelvic bones - the ischium, the ilium, and the pubis. Modern whales don't have these three bones - they have one bone (known because of a single ossification center which makes up the bone), considered to be the ischium. The attempts to label one end the ilium and one end the ischium is a superficial, deceptive attempt to homologize the bones to a quadruped pelvis. It would be like calling one end of a femur a different bone than the other end.This is another strike against the similarity to a quadruped pelvis. Take the last proposed ancestor - the basilosaurids, if you really want to compare them. The pelvis of a basilosaurus is composed of an ilium on the most distal portion, close to where the femur attaches. Inward from there is the ischium - which forms the upper arch of the obturator foramen. Then comes the pubis, the largest of the three fused bones, which is attached to the pubis of the the opposing side. Anyhow, the ischium is a small arched piece of bone - maybe 4 inches or so long. Compare that to the pelvis of a modern whale which is typically around a foot long, and is composed entirely of an ischium, and is a completely different shape than the bassilosaurus ischium. If you really want to compare actual bones, you have to compare ischium to ischium - and there is no comparison. You're missing the point and misusing the term "homology."Certainly every animal has a specific muscle for a specific role - but just because two animals have a muscle that makes the penis erect doesn't mean they are homologous. Examples of convergent evolution refute this notion from an evo perspective. Just because we call them by the same name, doesn't mean the muscles are similar in structure or are derived from a common ancestor. The muscles don't come with names on them. We give them names for simplicity sake. Imagine if we had a different name for the pectoral muscle for every species that has one. In depth analysis is done on the nerve patterns in the muscles - the only type of "name tag" the muscles have.There's no reason to disagree with Dr. Brazier on the in-depth point he was making - its not really a debatable issue. You found the right paper. Yes, drastic transformation indeed. Why should this drastic transformation sway the author? He already accepts as fact the common dogma. This is just one more large stepping stone evolution happened to climb.Just to be sure, I'm not saying my paper is supposed to refute whale evolution. You can accept all the points I make and still hold to the scenario. But, it should be clear that some of the prime evidence listed for whale evolution has been misinterpreted. That argument is not meant to refute the evolutionary origin of whales - just to highlight how the term "vestigial" can be more of a propaganda term than a useful term.Edited by Aaron, : not finished

DeletedEdited by GDR, : Deleted - Read admin's warning

---

Everybody is entitled to my opinion.

It is, of course, a logical inference, not a convenient excuse. This is why you are reduced to making dumb assertions rather than finding an actual flaw in my logic. We can. We can even see completely useless vestigial features before natural selection has weeded them out, which is what I presume you were trying to say, if they are (a) sufficiently recent (as in animals recently adapted to cave-dwelling, for example) (b) subject to only small selective pressures (as in the case of pseudogenes) (c) preserved in intermediate forms in the fossil record (as in the vestigial legs of primitive whales). Ah, that good old standby of creationism, the non-quantitative quantitative argument.While you're (a) doing some actual math (b) counting all the vestigial features in the world, the rest of us will continue the discussion. Come back when you've finished and tell us how you got on. It would be pointless for me to speculate on whether ignorance or dishonesty impels you to come out with nonsense like this; but I would point out that both conditions are in principle curable.Edited by Dr Adequate, : No reason given.

Hi Adminnemooseus,If discussion were to continue from Jar's reply to Slevesque it would likely draw a great deal of attention away from the whale anatomy discussion, so I agree that Jar and Slevesque should probably table that discussion, maybe it will become more appropriate later on.But I do think it an importance difference of opinion. Slevesque believes that we all look at the same evidence, we just interpret it differently. Jar believes that interpretations requiring unproven mechanisms are invalid. Many a theory has failed for lack of a mechanism even when right, as witness Wigner's theory of continental drift experiencing rejection until the posthumous discovery of mechanisms and more conclusive evidence. On the other hand, IDists believe they have the evidence showing that design happened and merely do not yet have evidence for how.But as important as this difference of opinion is, this isn't the right time, and probably not even the right thread. Maybe someone wants to propose yet another thread requesting that IDists propose a mechanism?Please, no non-admin replies to this message.

---

--	Percy
	EvC Forum Director

Okay, let's take a look at the developmental side of things. For the record, I pointed out that mice lacking SHh formed vestigial limbs, comparable to those of cetaceans. Aaron responds; I agree that the clue is in the title. "Mice lacking SHh". These mice lack all SHh expression. This is patently not the case in whales. If it were, they would not be able to form their front limbs. Indeed, they would not be able to develop at all and would die.Instead, we can see that SHh is active in whales, but inactive in their hind limbs. But this is not all. Take a look at this summary of an interesting paper on whale embryology;

quote:

---

Analysis of the development of limbs in a small number (fourdolphin embryos are not easy to come by, or casually used) of river dolphin (Stenella attenuata) embryos was sufficient to come up with a straightforward picture of the differences in molecular development.

​

Cetaceans form the AER for both the fore- and hind-limb. They express Fgf8. This is the normal tetrapod pattern.

​

Cetaceans form a ZPA for the forelimb. Hand2 is expressed broadly at first, and then is restricted to just the posterior part of the fore-limb; Shh is expressed in a perfectly ordinary fore-limb ZPA.

​

Hand2 is not expressed in the hind limb region. Shh is never activated. No ZPA forms for the hind limb, and the structure arrests and ultimately regresses.

---

Source. The paper this is taken from is here.What this is telling us is that SHh regulation is indeed a culprit in producing the vestigial cetacean hind limb, but it's not the only factor. The whales don't suffer any ill effects from lack of SHh because they don't lack SHh. Their SHh production is completely normal, except in their hind limbs.It also shows us that it only took relatively minor changes in signalling protein regulation (during development) to create the modern form off the cetacean hind limb. As I mention above, this is not even a consideration. Whales possess functioning copies of all of these molecules. They simply have mutations that affect the expression of these molecules in their hind limbs. The genes for these essential signalling molecules are still there, they're just selectively expressed. As we have seen though, other factors are at work, such as Hand2. That researchers are yet to find out how to exactly recreate the kind of structures that we're talking about only means that they haven't sussed it out yet. It does not argue against SHh, Hand2, Fgf and other factors creating the cetacean hind limb. Yes, and we can see from Thewisson's paper that this is exactly what happens.

quote:

---

We found that embryos of the pantropical spotted dolphin (S. attenuata) display a hind-limb bud with a morphologically distinct AER at their tip around embryonic stage Carnegie 13 (7). The AER persists and hind-limb bud outgrowth is sustained through Carnegie 15 (Fig. 1 A and B). Shortly thereafter, distal ectodermal cells lose their columnar shape, and the AER is lost (Fig. 1 C and D). After this degeneration, the hind-limb bud diminishes in size.

​

To determine whether the AER of the dolphin hind limb is functional at a molecular level, we next investigated whether it expresses Fgf8. Fgf8 protein localizes to the AER in both fore- and hind-limb buds of Stenella at Carnegie 14 (Fig. 2 C—F), consistent with the expression pattern in chick and mouse embryos (14, 15). By Carnegie 16, however, Fgf8 is undetectable in the hind-limb bud ectoderm. These results suggests that the dolphin hind-limb bud initially has a functional, albeit transient, AER.

---

So yes, the limb buds are indeed limb buds and they do display an AER. It just gets disabled (at about Carnegie stage 16, just as Aaron mentioned). Except that surgically removing the AER would not create a situation which could be fairly compared to that observed in dolphin embryos. It would not have the same effects upon Hand2, FGf8 or SHh expression that were observed by Thewisson et al.This is not a fair comparison. All arguments based upon this comparison are invalid. they seem to be similar enough to fool a team of anatomists and zoologists into thinking they were limb buds, even when they examined them in the tiniest detail.They look like limb buds. They behave like limb buds. They have the same chemistry as limb buds and, if they are allowed to grow, they form bones that are homologous to limbs.This is a remarkable co-incidence. Well, either that, or they really are limb buds.Incidentally, all this business about inactive signalling molecules may explain the appearance of femurs in Sperm Whales, even though they are toothed whales. The Sperm Whales would still carry all the genes needed to make a femur. It would just be disabled at the development stage. It would only take a few small mutations in the regulation genes and the femur and tibia would simply reappear, much like the way that modern chickens can be induced to grow actual teeth, with the application of the right signalling factor. the genes are still there. it's just the expression of those genes that has changed. As such, the appearance of femurs in an toothed whale doesn't sound quite so anomalous. With all due respect Aaron, I couldn't give a pair of foetid dingo's kidneys what they thought in the 1880s. They had an incredibly poor understanding of embryological development back then. You shouldn't be relying on such grotesquely old papers.One last thing before I wrap this up. The Thewisson paper doesn't restrict itself to looking at modern whales. it also posits some theories about whale evolution, based on their findings about how whale hind limbs develop.

quote:

---

Interpreting our results in the context of both the cetacean fossil record and the known functions of Shh suggests that reduction of Shh expression may have occurred ≈41 million years ago and led to the loss of distal limb elements. The total loss of Shh expression may account for the further loss of hind-limb elements that occurred near the origin of the modern suborders of cetaceans ≈34 million years ago. Integration of paleontological and developmental data suggests that hind-limb size was reduced by gradually operating microevolutionary changes. Long after locomotor function was totally lost, modulation of developmental control genes eliminated most of the hind-limb skeleton. Hence, macroevolutionary changes in gene expression did not drive the initial reduction in hind-limb size.

---

Here is a nice diagram showing when they think these changes may have taken place. So in stark contrast to any claim that examination of cetacean limb buds proves that they are non-limb related structures, in fact, such research shows strong evidence that the buds are indeed limb buds. Further, it sheds light upon the evolution of whales from their longer-limbed ancestors, such as Basilosaurus.Mutate and SurviveEdited by Granny Magda, : No reason given.

---

On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

Continuing... Agreed. You haven't provided any evidence that any whale "femur" is actually a bone tumour. Indeed, it does not resemble a tumour. It resembles a femur. plus, as Dr A has pointed out, it seems instructive that these alleged "tumours" always appear where the femur should go.I know exactly why the femur always appears where it does.Can you suggest why a bone tumour should overwhelmingly favour that site? Further, since you are explicit about your belief that God created the whale, why would he create them so as to display bone tumours that so closely resemble femurs that even the world's top zoologists can be fooled? Why is he so keen to make these animals look evolved? Just like the cartilage that we have on our acetabular cavities. Another homology. It absolutely is a debatable point. The picture I presented showed a very clear notch, right where the acetabular notch should go. Right where the femur does go. What else could it be?Certainly, it is far less pronounced than a terrestrial animals acetabular notch, but that is not surprising. This is part of a pelvis that is attached the wrong way round! It is a highly derived, very unusual pelvis. We should not expect it to be a perfect match for terrestrial animal pelves. Rather, we should expect that it would look very different, with some features missing and some grossly warped. This , in fact, what we see.I also think that the reason behind the drastic reduction of the acetabular cavity is pretty obvious. It no longer articulates a mobile, weight-bearing femur. It is no longer part of a skeletal system that is used for quadrupedal locomotion. Without this function, it seems almost inevitable that natural selection would not be able to shield this near functionless appendage from the effects of mutations. The feature would diminish, just as we see today. From looking at the available literature, I agree that the modern whale pelvis is considered to be homologous to the ischium. You're right about that. However, homologies still exist. Much as you might try to deny them, the homologies around the ischium - the acetabular cavity, the femur, the musculature (more on that in a moment) - the comparisons are obvious. The pubis and ilium might be impossible to detect, but there is plenty more to go on. Just because two mammals have a muscle, that extends from the pelvis to the base of the penis/clitoris, doesn't mean that there is any connection between those muscles. Uh-huh.It is described as a homologous ischiocavernosus muscle in the scientific literature, such as in Notes on the Anatomy, Postioning and Homology of the Pelvic Bones in Small Cetaceans, where the ischiiocavernosus and the levator ani are explicitely described as homologous.

quote:

---

In this study, the attachment of two muscles to the pelvic vestiges — levator ani and ischiumcavernosus is confirmed. The levator ani is attached to the haemal arches and to the ischium of many mammals, including the artiodactyls (Habel, 1975). There is currently a broad consensus that, among the extant groups, artiodactyls are the most commonly cited as the sister group of the Cetacea, and that perhaps they even form a clade (Gingerich et al. 1983; Thewissen et al., 1994; Gatesy, 1997, 1999; O’Leary and Geisler, 1999; Gingerich, 2001, Gatesy and O’Leary, 2001; Thewissen et al. 2001). In cetaceans, this muscle arises in the haemal arches and is inserted to the dorsal margin of the pelvic bone (Lessetisseur, 1968: 692-693), more specifically at the dorsolateral crest and ventromedial protuberance of the cranial process, a name suggested by Duvernoy (after Arvy, 1979).

---

quote:

---

The ischium-cavernosus muscle arises in the ventrocaudal portion of the pelvic bone, which is usually called ischial tuberosity, both in cetaceans and in all other mammals

---

But the paper I just cited disagrees with Brazier. Clearly it is more debatable than you think. It's odd how you simultaneously cite Tajima and yet don't believe a word he says. When he says that whales may use their pelves in locomotion, you jump on it. When however, he says;

quote:

---

Muscles such as M ishciocaudalis, M ischiocavernosus and M bulbospongiosus have attachments on the pelvic bones in both sexes. Moreover, we confirmed that the caudal end of M. rectus abdominis (RA) constitutes a strong dorso-caudad aponeurosis (Fig.1, B), after sending a small muscular slip to the pelvis (Fig.1, A) and inserting at the superficial fascia of M. ischiocaudalis (Fig.1, C). In the most caudal portion of M. transversus abdominis (TA), the strong inner fascia of TA originated at the Proc. transverses and suspended the pelvis as part of the abdominal wall (Fig.2). It should be emphasized that insertion B is much the same as that of the terrestrial mammals.

---

you dismiss him out of hand. You are cherry-picking. If you think that Tajima possesses sufficient expertise to correctly diagnose an active role in locomotion of the cetacean pelvis, then you really ought to credit him with enough expertise to tell which muscle is which.The fact remains that the source you cited regards the ischiocavernosus muscle as being homologous with that of terrestrial mammals. Yes, I think it's fair to say that laymen such as myself make mistakes on this. The pubis and ilium being a good example. I will admit to being wrong on that myself. However, the mistakes made by layman enthusiasts such as myself do not count as serious flaws in evolutionary thinking. You cited the technical literature. That work, has built a scientific consensus that goes against many of your claims. The experts in the field regard these bones and muscles as being homologous with those of terrestrial quadrupeds. You can't get away from that. Except that you cannot provide us with an explanation for why these bones so resemble legs. I can. Vestigial is that reason. Meanwhile you are forced to grope around for a pot-pourri of diverse rationalisations, from bone tumours to muscle anchors that must, for unspecified reasons, resemble legs.I think that far from being propaganda, vestigiality is by far the most parsimonious explanation for these features.Mutate and Survive

---

On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

If you are referring to the positioning of the pelvis and femur in this picture, it is not accurate. What they are doing (I'm assuming) is rotating the pelvis so you can get a better view of what the bone looks like. If you looked at it straight on from this angle, you wouldn't see very much. But, if they don't give you a disclaimer telling you that is what they are doing, you are left to reason that they are accurately showing you the true orientation.If you want to see a paper with the true orientation, check out this: link It's on page 14 and coincides with the diagram I already provided. Hox mutations don't always produce an exact duplicate - and I wasn't indicating that these hind flippers are perfect duplications of the front flipper. Usually the duplicated part is abnormally developed. For example, my son was born with an extra digit growing from below his thumb, yet it was nothing more than a nub - a single phalange with no nail.Dorudon has three foot digits (which is less than his forelimb). The sperm whale mutation has two digits. So either way, it is an incomplete mutation. Notice how the round carpal bone in the x-ray matches the round carpal bone in the sperm flipper. You see no such thing in Dorudon.And what about the 4 foot long hind limb in the humpback whale example? How is that at all like Dorudon? Several misrepresentations of what I've said.I didn't claim that the hind limbs of Dorudon were sexual claspers - the guy who discovered the fossil did.My thought is that these types of mutation more readily occur in regions where there are already similar genes at work. The formation of the genitals and the mammary gland include several genes that are also involved in limb formation.Can you even explain how an atavistic reversion occurs? How does an ancestral gene get turned back on?you might find this interesting: http://www.epigeneticscomesofage.com/Chapter_16.html

Hold on. Surely those photographs are taken from the inside looking out; that is, with the medial side facing us. This is why the attachments of the corpus cavernosum are on the side facing us. And why the femur is on the side facing away from us. Granted, but you can't claim that the similarities are so great as to particularly suggest that the hind flipper is a Hox-mutation induced duplicate of the front flipper. If you now wish merely to claim that the differences aren't so great as to prove that it definitely isn't, then that is a much weaker claim. I could only see two on the photograph; do you have a reference? Thanks. Well according to this, that isn't a "rounded carpal bone", or even a rounded tarsal bone. That's the femur (or, according to your "front limb" hypothesis, the humerus). The next two bones are the tibia and fibula (or, according to your "front limb" hypothesis, the radius and ulna); there are no tarsals (or carpals); and then after that we get into phalanges.The passage quoted in the link doesn't say how they reached this identification of the bones, but they did look at the whale and we didn't. It's like Pakicetus. Seriously, again I'd like a look at your source material before coming to a conclusion. I did not intend to misrepresent you. We discussed these "claspers" at length and you never so much as hinted that you didn't think that that was their function.Indeed, what you wrote about Dorudon was as follows: Now, you did not mean that you had probably read reports saying this about Dorudon, did you? You meant that this was probably true of Dorudon, did you not?So how did I misrepresent you? Given that limb formation involves the production of bones, muscle, nerves, blood vessels, etc, so must the formation of pretty much everything else.Also, we do not actually see these supposed extra forelimbs growing out of the genitals or the mammary glands, do we? We see them growing where the hindlimbs would grow.Do we, in other mammals, see a consistent pattern of extra hands growing out of or near the breasts and genitals? Or does this by a freakish coincidence only happen in whales? I should think that that would vary from case to case. It must be difficult to catch happening, especially in whales, so I doubt that there is hard evidence in this case. The facts are interesting; his gloss on them I found rather silly, for reasons which would be outside the scope of this thread.Edited by Dr Adequate, : No reason given.

Granny M,Thanks for the thoughtful reply and good questions. Not quite. Even without Shh, the mice still developed front and back limbs - just not complete limbs. And yes, they did die early. So minor, they can't duplicate it in the lab. When scientists want to explore the affects of silencing Shh or Hand2, they have to silence it completely. They don't have a way to selectively silence it in just the hind bud. Yes, because if you knock out Shh, Hand2, or Fgf8, you still get a limb that develops much more thoroughly than the cetacean condition. It certainly is comparable - especially since the Hand2, Fgf8, and Shh would not be eliminated from the whole body if you cut off the AER - just silenced in the one region. These proteins are intertwined. One promotes the production of the other. Removing the AER stops these proteins from being expressed. They are limb buds why? Because they have an AER? An AER is just a thickened area of ectoderm at the end of the limb bud - a situation just like the early formation of the mammary gland - even in humans. In fact, even in humans, the formation of the mammary gland begins as protruding ridge - the mammary hillock. Later, this ridge regresses. After it regresses, a secondary bulge emerges which becomes the external part of the mammary gland. Sounds familiar to what happens in cetaceans.Contrary to what you said, the hind buds in cetaceans do not look or behave like limb buds. The AER is much smaller and more localized to a small spot. The buds themselves are much smaller than a typical hind limb bud - despite how long they are actively developing. Chemically, they are lacking Shh and Hand2 - as you pointed out.The only similarity is the presence of an AER and Fgf8. As I mentioned, an AER is also part of a developing mammary gland - and Fgf8 is also a critical protein for the earliest stages of mammary gland development.Here are some more problems for you to chew on. Studies have also been done on the limb buds of gray whales and minke whales. You see the same situation where the buds regress into a fold of skin without developing any skeletal elements. Yet, both of these whales have femur bones. Where did they come from if the "limb buds" regress? If they didn't come from the "limb buds," can you call them limb bones? Seems like they are something entirely different. Except that the femur is always there in sperm whales. No need for this conjecture. Seriously? You're evidence for this is what? Actually, when I presented this information to a marine biologist, he commented on how much great work in anatomy came from that time period.Consider this before you make such a nonsensical comment: Back in the 1880s, whaling was big business. As such, it provided scientists with many more specimens to study if they were looking to study embryos. If you want to study whale embryos, you are limited to the chances of a killed whale being pregnant - and then if it happens to be pregnant at the developmental stage you are interested in.The chances of obtaining beneficial specimens were much greater back then than they are now in our age of very regulated cetacean specimens.

I'll leave the genetics to GM, who has a head start on me. A few words about embryology, though. Very familiar. This paper, for example, on the humpbacked whale, describes an embryonic stage at which the "peg-like hind limb buds" are visible and "a bilateral thickening, the milk line, extends between the limbs". The ridge and the hind limb buds are two different things. Like in all the other mammals.(Incidentally, while looking this up I noticed that a human embryo develops and then loses supernumary nipples along the milk line, but that would be a subject for your other thread.) Also, they don't turn into limbs. That's another difference. I wonder if there could be some connection between these facts.

Yes, I know. We are agreed on what happens in this case. Just because it cannot be recreated does not mean it never happened. This only argues for the imperfection of scientific expertise in an area with little opportunity for study. Or do you think that scientists are gods, able to recreate anything that nature can do? One minute you act like the scientists should be able to achieve anything they might want, the next, you are dismissive of their findings. This is a strange attitude. Do you have any evidence for that? Please cite it if you do.Still, I don't see why you expect cetacean limbs to behave exactly as those of terrestrial mammals, when, as you yourself have gone to great pains to point out, they have undergone a lot of adaptation in specialising for new roles.Embryological development is incredibly and to expect that human scientists should be able to reproduce any given condition in the lab is naive. And what happens when the proteins are down-regulated but the AER is not removed? Can you tell me that? Because that's what is happening in whales. That is what happened in Thewisson's dolphins.If you can show me an experiment where that happens, then great, but until then, the mouse experiment is not one that I consider a perfect match. It is instructive yes, and indeed it shows that SHh down-regulation results in reduced limbs, but it is not reproducing the exact situation that we know occurs in whales. What is your evidence for that? Yes! Also because of all the other similarities I have outlined - anatomy, morphology, chemistry. Indeed, the only areas in which is does not resemble a limb bud are those factors that would have to be different for the limb to have evolved the way it did.Yes! They have to be! If they were not, a full hjind limb would grow there!In fact, this would suggest a fantastic creationist experiment. Take one dolphin embryo. Open up the flank and expose the limb bud at around Carnegie stage 15/16. Introduce SHh and Hand2. If it grows into a great big whale boob, then you have falsified the hind limb hypothesis. But sadly, creationists organisations don't show much enthusiasm for actually doing science. Aaron, you have to get out of this bad habit of citing studies without actually citing them. Which studies? Please name them and, if possible, provide a link. It is not fair to ask me to do your homework for you. No, you misunderstood what I was saying. I was talking form an evolutionary, natural history point of view. I was talking about the whole species, not individual Sperm Whales. The point remains that no genes were lost during the process. They were simply down-regulated in a single area. That, in one species, that down-regulation should be weakened is not all that astonishing. It is surprising - don't think that I didn't notice the presence of a toothed whale amongst your list of mysticetes - but when we see how small a genetic change is required for the femurs to reappear, it seems like small beer. Please. They knew about anatomy. Anatomy is not embryology. This kind of highly detailed embryology is new. They did not know about the chemicals and processes we're discussing in the Nineteenth Century. They had no way to examine the chemical side of embryological development. SHh was not discovered until 1978 and it was not understood until 1995. These things are still being discovered now and we still do not have an especially full understanding of their function. To suggest that a Nineteenth Century understanding of embryos is comparable to our modern one is just silly.Mutate and SurviveEdited by Granny Magda, : No reason given.

---

On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

indeed organized creationism has said the marine mammals did not evolve from land.
This YEC creationist insists marine mammals were all from the land and descendants off the Ark.
They simply filled a empty post flood sea.
i welcome and want to find great evidence for marine mammals being post flood adaptations.
In fact they make the case against evolution because they are amongst the very few creatures with remnants of former anatomical structures indicating a previous type of body.
If evolution was true all creatures should be crawling with remnants of this and that.
In fact only these creatures obviously first land creatures have these vestiges.
They could adapt to the seas so far but not do the full fish thing.
In fact since creationism teaches there are only kinds and common details are just because of common needs then it could only be that marine mammals are the original like needs of mammals.
I mean that there are no such creatures as mammals but only like needs bred like details in unrelated creatures.
I don't see a evolution of land to marine but rather such rapid adaptation that some mothers son could swim but not mom.Marine mammals could only be from land creatures and indeed creationists should embrace this .

HI Robert,Oh dear. You have decided to clutter up Aaron's nice thread.Suffice to say that, where Aaron brings evidence, you bring nothing. You say "This YEC creationist insists", as though your insistence alone could make your fantasies true. It's pathetic.Even worse, where you do make specific claims, you are painfully wrong. That is wrong. Not just a little bit wrong, but staggeringly, woefully, embarrassingly wrong. Just google Sirenians to see how wrong you are. They display very similar hind-limb structures to those of whales. Further, there are vestiges and homologies throughout the animal kingdom.That is evolution you strange man.Look, you're not achieving anything here beyond letting your amazing ignorance hang out for all to see, so might I ask that you don't mess up this nice thread with your vague and semi-literate ramblings? Please? Thank You.Mutate and Survive

---

On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage