Posted on 05/20/2006 6:02:56 PM PDT by Al Simmons
Fetus' Feet Show Fish, Reptile Vestiges By Jennifer Viegas, Discovery News
May 18, 2006 The feet of human embryos taking shape in the womb reveal links to prehistoric fish and reptiles, a new study finds.
Human feet may not look reptilian once babies emerge from the womb, but during development the appendages appear similar to prehistoric fish and reptiles. The finding supports the theory that mammalian feet evolved from ancient mammal-like reptiles that, in turn, evolved from fish.
It also suggests that evolution -- whether that of a species over time or the developmental course of a single organism -- follows distinct patterns.
In this case, the evolution of mammalian feet from fish fins to four-legged reptiles to four-limbed mammals to human feet appears to roughly mirror what happens to a maturing human embryo.
"Undoubtedly there are clear parallels between the mammal-like reptilian foot and the human foot," said Albert Isidro, an anthropologist at the Autonomous University of Barcelona, Spain and lead author of the study, which appeared in the journal The Foot.
Isidro and colleague Teresa Vazquez made the determination after analyzing fossils of a number of mammal-like reptiles that lived from 75 to 360 million years ago. The scientists also studied fossils of osteolepiform fish, which appear to be half fish and half reptilian. These fish lived 400 million years ago and had lungs, nostrils and four fins located where limbs would later be found in four-footed reptiles and mammals.
In 33-day-old human embryos, the scientists observed "the outline of a lower extremity in the form of a fin, similar to that seen in osteolepiform fishes." As the embryo continued to develop, the researchers focused their attention on two foot bones: the calcaneous, or heel bone, and the talus, which sits between the heel and the lower leg.
At 54 days of gestation, these two bones sit next to each other as they did within the reptile herbivore Bauria cynops, which lived around 260 million years ago. This ancient reptile had flat, crushing teeth and mammalian features.
At eight and a half weeks of gestation, the researchers found the two embryonic foot bones resemble those seen in the Diademodon vegetarian dinosaur, which lived around 230 million years ago.
"We can tell that the embryo is half way between the reptiles and the mammals (at this stage)," Isidro told Discovery News.
The two foot bones continue to develop until, at nine weeks, they resemble that of placental mammals as they emerged 80 million years ago.
This development of feet in the human embryo mirrors how the foot evolved over millions of years beginning with fish and ending with early mammals, according to the scientists.
Supporting the fish/foot link was the discovery last month of a new species, Tiktaalik roseae, which lived 375 million years ago. It had fish fins and scales, but also limb parts found in four-legged animals.
"Tiktaalik blurs the boundary between fish and land-living animals both in terms of its anatomy and its way of life," said Neil Shubin, professor and chairman of organismal biology at the University of Chicago and co-author of a related paper in the journal Nature.
H. Richard Lane, director of sedimentary geology and paleobiology at the National Science Foundation, said, "These exciting discoveries are providing fossil Rosetta Stones for a deeper understanding of this evolutionary milestone: fish to land-roaming tetrapods (four limbed animals)."
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Exactly.
Here's another diagram
Finally. Creation science at work.
Next month we'll hear from the creationists that fetuses aren't really human because they're not mentioned in Genesis. Babies are examples of special creation just before their born.
All that weight gain and movement are "just rocks."
LOL
Great bookmark. Thanks!
So, what do you mean by "this"?
"So, what do you mean by "this"?"
Eliza, is that you?
I'll take that as an answer to my question.
Half right.
Perhaps you would care to outline the errors in Haeckel's drawings. You may use the photographs as a reference. I'm not saying there aren't any errors in Haeckel's drawings. I just bet you can't describe them in any detail. Check out the photographs.
Don't. You are responding to a professional troll. He goes from thread to thread and disagrees with the most rational position.
No, I wouldn't care to do anything like that at all. I'm not qualified to do anything like that, though I believe the researcher named in the summary article I posted could do so. It's amazing to me. I noticed this thread and posted a comment (with support) about the historical problems the "ontogency recapitulates phylogeny" idea has encountered, and I get back a barrage of accusation and invective from people who are evidently Evolution Zealots. I have read that Clarence Darrow (pictured so appealingly in "Inherit the Wind") came across the same way. I suspect this sort of humorless fanaticism helps explain why proponents of the teaching of evolution have won so many battles but keep losing the war for the hearts and minds of Americans.
What relevance does a 100 year old controversy, long since resolved, have on the current article?
The fact that you can't describe the errors in Haeckel's drawings, as compared to photograps, indicates the errors are rather small.
Creationists aren't interested at all in the 100 year old scientific dispute. They don't want the drawings displayed because they support common descent. The problem is, that when the drawings are corrected, they still suport common descent.
It's obvious they've made up their minds that ontogeny IS Haeckel.
Sorry, whenever I hear the word 'platypus', that song comes to mind. It's a real song meme or ear worm. It is a good song though.
Ha! Looking up 'meme'.... it was introduced by Richard Dawkins. LOL! That guy gets around.
http://en.wikipedia.org/wiki/Meme
I answered your question in post #54:
I have no quarrel with the general theory of evolution, but I think it's worth noting that the "ontology recapitulates phylogeny" theory has been supported with a whole lot of wishful thinking as well as willful fraud. I cannot help but wonder if the present "study" has included one or the other.You know, I'm very sorry I wandered onto your turf. Just keep harassing and ridiculing people who raise the very slightest questions about what you're saying. After a while (a hundred more years, maybe), you'll have browbeaten everyone into submission.
I just want to know why you think bringing up Haeckel is relevant to the current discussion. It strikes me as equivalent to trying to discredit chemistry by bringing up phlogiston.
You aren't going to like the embryo drawings after they are corrected any more than you like the uncorrcted ones.
Clinton? Is that you?
Just because they reason like liberals doesn't mean they are all Clintonistas.
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