The jaw of Teinolophos trusleri catches the ear bones in the act of separating from the jaw.
Posted on 02/11/2005 6:49:09 AM PST by PatrickHenry
Triple bone structure arose independently in platypus and humans.
Listen up: mammals seem to have evolved the delicate bone structure of the middle ear at least twice. The surprising discovery comes from a fossil, found off the southern coast of Australia, that belongs to an ancestor of the platypus.
Modern mammals are unique among vertebrates for possessing three tiny bones in the middle ear. The malleus, incus and stapes (commonly known as the hammer, anvil and stirrup) work as part of a chain that transmits sound towards the skull. Birds and reptiles have only one bone to perform this function.
Because the mammalian arrangement is so complex, scientists believed that the set-up had evolved on just a single occasion, in an ancestor that gave rise to placental animals (including humans), marsupials and monotremes (such as the duck-billed platypus).
All this changed when James Hopson, a vertebrate palaeontologist at University of Chicago, Illinois, took a trip to Australia. There he met a team of researchers including Thomas Rich of Museum Victoria in Melbourne.
The jaw of Teinolophos trusleri catches the ear bones in the act of separating from the jaw.
Rich and his colleagues had recently unearthed a fossil of Teinolophos trusleri, an ancestor of modern monotremes that lived 115 million years ago. "He said he had some new Teinolophos specimens and when he showed them to me I almost fell off my chair," says Hopson, an author of the study, published this week inScience [Rich T. H., et al. Science 307, 910 - 914 (2005)].
Hammer time
Palaeontologists believe that the middle-ear bones of modern mammals once belonged to the jawbone and later separated to adopt their present location. This is supported by the fact that the middle ear's bones associate with the jaw in the early development of modern mammalian embryos.
What makes theTeinolophos specimen surprising is a large groove in its adult jawbone, which indicates that the smaller bones had not yet detached.
Teinolophos lived after monotremes split from the placental and marsupial mammalian groups. Its jawbone structure, along with its place in the evolutionary tree, hints that a common ancestor to all these mammals lacked the special three-bone ear structure.
This means that natural selection must have driven the same rearrangement in independent groups, after the monotreme split. "Some embryologists had the idea that it might be convergent but nobody really believed this," says palaeontologist Thomas Martin of the Senckenberg Research Institute in Frankfurt, Germany. "I was quite shocked when I heard that such a complex morphological transformation happened twice."
The discovery will compel many experts to rethink their appreciation of mammals' common evolutionary heritage. "Until now it was considered to be one of the most important shared derived characteristics of modern mammals," says Martin.
I'm leaning now toward the idea he'd succumb to the toxic effects of ketosis if very lean times ever hit. Breaking down protein for calories is hard work for the liver and kidneys even for people who have some fat reserves in addition.
That's probably why we have myostatin in the first place, to prevent muscle buildup from blocking fat buildup so we don't go into lean times too lean.
Wonderful as muscle is, it's expensive. It costs fat. That never comes up, never matters, now for most of us. This knowledge, once essential, is now hidden.
Fat is cheap. Fat is easy. Fat takes nothing but sitting around watching the game and munching potato chips.
Fat used to be precious. The literature is still replete with references. "Living off the fat of the land." "The fatted calf." Heck, "Fat City" and that's only from the 70s. The "cream" of the crop.
Well, fat used to be harder to do. We have it pretty nice, when you think about it.
So they don't even agree with their own talking points. Someone may have called the platypus "degenerate," but all it means is that is has acquired too many cute specializations. The fossil monotremes tend to be described as more generalized as you go back in time. The platypus has run up a few evolutionary blind alleys and now has very few places it can live.
I guess it's hardly your fault if ICR can't even keep its own talking points straight. (Are you really so screwed up you think this is going to replace mainstream science?)
Balderdash!
Flapdoodle!
"As I understand it, evolution is theoretically propelled by weeding out diversity within isolated populations by natural selection and genetic drift, the opposite of your attempt at PC."
I hope you are not a biologist. Your understanding is almost backwards.
I am the least PC person you know. Does it discomfort you to know that blacks are more evolved than you are? It sounds like you should be on the DUmmie list arguing against Condi and Gonzales.
"The fossil monotremes tend to be described as more generalized as you go back in time." -VadeRetro post 302
"Someone may have called the platypus "degenerate," but all it means is that is has acquired too many cute specializations." -VadeRetro post 302
If you want to call loss of teeth a "cute specialization" instead of a generalization, ok. To me, it's just another case of loss of functionality, that evolutionists insist are examples of added functionality.
And it looks to me that it's your talking points that are in disarray. That and the false talking points you keep wanting to ascribe to Creationists, like significant differences aren't suppose to occur. Degenerative differences and speciation within original genetic potential are part of creationist theory.
I notice you don't have any comments on the fact that evolutionists were wrong about marsupials developing in isolation in austrailia. All that ridicule that Creationist's have endured from evolutionists on how did the marsupials get to Austrailia and only Austrailia, as if that proved anything, just flew back in your faces.
"The fossil monotremes tend to be described as more generalized as you go back in time." -VadeRetro post 302
"Someone may have called the platypus "degenerate," but all it means is that is has acquired too many cute specializations." -VadeRetro post 302
If you want to call loss of teeth a "cute specialization" instead of a DE-generation, ok. To me, it's just another case of loss of functionality, that evolutionists insist are examples of added functionality.
And it looks to me that it's your talking points that are in disarray. That and the false talking points you keep wanting to ascribe to Creationists, like significant differences aren't suppose to occur. Degenerative differences and speciation within original genetic potential are part of creationist theory.
I notice you don't have any comments on the fact that evolutionists were wrong about marsupials developing in isolation in austrailia. All that ridicule that Creationist's have endured from evolutionists on how did the marsupials get to Austrailia and only Austrailia, as if that proved anything, just flew back in your faces.
I love that game.
Ok, go ahead and post some more creationist stuff we have all debunked before.
Come up with some scientific evidence for your position and I will start taking you seriously again.
You don't lose 'em unless you don't use 'em. Ducks don't have teeth either.
Degenerative differences and speciation within original genetic potential are part of creationist theory.
You have nobody to answer the usual questions from the above bit of sophistry.
Even some boys in TN know that there are possums in North America. Get a clue, son. Marsupials were well established (more or less unchallenged by placentals) on Gondwanaland. They were on all the pieces when it broke up. They reached North America from South America later, after they came into contact.
I don't have time tonight to put you through High School.
There are no native marsupials in Eurasia. (They may have originated there, but that's another story. There haven't been any native to there for a long, long time.) Not oppossums. Certainly not those eucalyptus-only-please koalas of Australia and only Australia. So, are all marsupials one created kind? The thylacine and the possum and the koala and the kangaroo and the wombat?
You still have a problem with a koalas (and quite a number of other uniquely located species) until you actually address it. Mt. Ararat is a long way from marsupial country. It certainly isn't in South America or even North America.
What's degenerative and how do you know it?
(Answer: First, try to deny. If you can't deny it, it's either degenerative and/or microevolution. What a science!)
Mr. USOTOS, this guy supposedly teaches college-level biology(IIRC).
And on every dinner table in West Virginia.
At least I know to capitalize Blacks ;-)
When you show me an empty room, then want to brag about the expensive furniture in it, your complaint is rather empty. I don't choose to disregard anything. I'm looking at the same material - I'm just not going beyond what can factually be stated about the material. You are. And that is your problem. You can't support your conclusions. You present one fact - the existance of a bit of matter (a partial skeleton), and from it you extrapolate a book. There is a limit to what fosilized bone can tell you. And that limit does not give rise to a book. Your suppositions and unfalsifiable conclusions may fill a book; but, that isn't science. I don't disregard what you present. I simply read it, assent to the actual evidence (the bones) and correct the conclusions beyond that by noting there is no support for the conclusion beyond wild supposition and speculation. You want your speculation regarded as fact and assert it as though it is by default. That is the MO of your crowd. And it is improper and unscientific. What's more, it always has been. But you've gotten by with it as a community for so long, that you're insensed that anyone now dares call you on it. Get used to it, it's getting worse every day for you. You'll have to produce results - real results. And IMO, you can't.
Micro-evolution has nothing to do whatsoever with the larger theory? Micro-evolution is the basis for the larger kind.
Just love spinning them wheels in hopes someone will be fooled - don't ya.
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