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.
oops, sorry guys, computer problems.
Make sure you read my post 391. It completely destroys Havoc's arguments.
So what you are saying is that the same ear structure developed in two different branches of the evolutionary tree?
The chances of something like that occurring without intelligent guidance is pretty darn close to nil.
Hillary belongs to a class of animals that has been relegated to mythology.
The Harpy was a creature both human female and bird. Their purpose was to torment men who displeased the gods.
Hillary having both shrill voice and claws has transferred he venom for the taxpayers.
Natural selection easily explains homologous structures forming for a certain structure that has survival benefits for the population.
Since we see the development of the structure, it does not matter what the "chances" are. What evidence do you have for a " intelligent designer", besides a hunch.
Evolution says the designer is natural selection.
Run away! Run away! LOL
I got betta.
Well, 'easily' if you presume that, as the structures were slowly evolving and not really serving any purpose, they were somehow 'selected' during the reproduction process and continued to form until they were useful. You'd also have to assume that this same 'blind' process happened not only once, but twice.
That might sound reasonable to you, but it doesn't to me.
"Since we see the development of the structure, it does not matter what the "chances" are."
If all you are claiming is that the structures exist, then true, the 'chances' discussion doesn't apply. If you extend your claims to saying that a non-intelligent 'something' (in this case 'natural selection') caused this design to happen not only once, but twice, then chance is indeed part of the discussion.
"Evolution says the designer is natural selection."
Evolution can't speak or type. That's what you 'say'. I say differently.
"You'd also have to assume that this same 'blind' process happened not only once, but twice. That might sound reasonable to you, but it doesn't to me."
Argument from personal incredulity.
"If you extend your claims to saying that a non-intelligent 'something' (in this case 'natural selection') caused this design to happen not only once, but twice, then chance is indeed part of the discussion."
Obviously the bones were present in reptiles since they had a multiboned jaw, the genetics were predisposed to do this since it already happened once and better hearing is a survival adaptation, there is not much of a stretch. So it is not all chance. However, I am not too sure yet about this particular finding. It may be that there are still some fossils to be found that might clear some of this up and that this branch of monotremes came from the node of common inheritance with mammals with 3 bones in the ear.
You must understand the basis for evolution, the science behind it and the obvious fact that there is some structure to the molecules. I don't discount the fact that God could have designed the Periodic Chart, but He did not create each life form separately and probably didn't directly create first life. Just by "let there be light" an omnipotent God could have created everything through coversion of energy to matter.
"You'd also have to assume that this same 'blind' process happened not only once, but twice. That might sound reasonable to you, but it doesn't to me."
Argument from personal incredulity.
"If you extend your claims to saying that a non-intelligent 'something' (in this case 'natural selection') caused this design to happen not only once, but twice, then chance is indeed part of the discussion."
Obviously the bones were present in reptiles since they had a multiboned jaw, the genetics were predisposed to do this since it already happened once and better hearing is a survival adaptation, there is not much of a stretch. So it is not all chance. However, I am not too sure yet about this particular finding. It may be that there are still some fossils to be found that might clear some of this up and that this branch of monotremes came from the node of common inheritance with mammals with 3 bones in the ear.
You must understand the basis for evolution, the science behind it and the obvious fact that there is some structure to the molecules. I don't discount the fact that God could have designed the Periodic Chart, but He did not create each life form separately and probably didn't directly create first life. Just by "let there be light" an omnipotent God could have created everything through coversion of energy to matter.
I was the best science teacher most of them ever had, and I'll get a couple who are adults now to tell you that if you don't believe it- but then I suppose it would not alter your opinions in the slightest.
As for me being "hostile to inquiry", for the love of reason, can't you see the rank hypocrisy in your post? It is you that expresses the most virulent hostility to me for making some inconvienient inquiries such as "gee, isn't X another possible answer for the observed facts?". You are precisley what you accuse me of. The blindness of an otherwise intelligent man sends a literal chill down my spine.
As for your arguement that a lot of improbalble things can happen in 4.5 billion years I reply 1) your numbers are wrong as all of the improbable things we are talking about occured in the last 543 million years since the Cambrian explosion and 2) Even 4.5 billion years is not enough time to make a huge series of extremely improbable events occuring by natural means a reasonable position. We must compare the number and likely hood of the events to the time allowed.
The numbers are not wrong. You are failing to comprehend the geometric nature of the calculation.
The "Cambrian explosion" was millions of years and the Precambrian was longer than the Cambrian. Your students may think they were well instructed, but most of us who also have taught biology are beginning to have our doubts about your claims.
As to the rest of your post, I'm glad to see you are open to God being the 'uncaused cause' for life.
It is you who fail to comprehend my point from two posts back. The thread is about a repetition of an event in different lines of mammals that would appear unlikey to evolve independently. They countered that 4.5 billion years a lot of unlikely things can happen. My reply in part was that the things we are talking about- independent origin of ear bones in mammals and flight in stick insects- are in the higher animals.
Higher animals emerged- with a few possible exceptions, not 4.5 billion years ago but a mere 543 million years ago. All of the independent re-evolution that seems so unlikely happeded since the explosion. That means seven eights of Earth's history is not available to give time for these "unlikely chance events" to occur.
"Obviously, the amount of stretch required is a matter of opinion."
No its a matter of prediction from the ToE.
"As to the rest of your post, I'm glad to see you are open to God being the 'uncaused cause' for life."
I am not just "open", I KNOW it. How could anyone be a Christian, especially a Christian Minister without believing in God as Creator? Our whole country is founded on that premise.
What I don't like is your side promoting a bunch of superstitious nonsense that drives people away from Christ, instead of allowing them to accept the Gospel and reach salvation. Can't you see this?
You are just wrong. We have tried to explain the mechanisms involved that make you wrong. You have not conceded an inch from your original stance.
I suggest you read up on biology to a greater extent and try to separate your religious opinions from objective fact.
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