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.
All right.
So tell me...how does genetic drift in an isolated population of vertebrates drift so far that the population loses or gains one or more chromosome pairs, remaining viable but no longer cross-fertile with the populations of its fellows from which it has been isolated?
Variations of traits within a species and the rise of one species from another are two different things, different by an order of magnitude. I suspect that theory has an answer for this question, and I would be open-mindedly interested in hearing what it is.
http://www.talkorigins.org/faqs/genetic-drift.html
The above is an article on genetic drift.
There are no boundaries to accumulated genetic change. If a chromosome breaks up or comes together and transfers to a litter of animals in the sexual process, it might be the basis for a new chromosome number in a new species.
Since naturally occurring speciations only occur about 4 times in a million years in a given population, it is rather difficult to observe. Many speciations have been observed. Species do not necessarily have different numbers of chromosomes, however. I hope you don't think that is what constitutes a species.
Mother and daughter species are generally so close in characteristics it is difficult for anyone but experts to tell them apart. That is one reason why the nonsense the creationists put out about no speciation occurring is so dishonest. No one can tell a species differentiation in a skeletal structure. Only larger differences are apparent.
Thus, it may appear to the laymen that life forms jump by Family differences from one thing to another. This is just not true. Everything is done in species steps. This is what is known as "gradualism". It is only looking back in the fossil record and seeing the history of changes that scientists can observe large scale changes from one Class to another. The Reptile to Mammal changes are well documented. There is a paper on talk origins that discusses that too.
To be fully versed in paleontology or genetics to be conversant with all the details of even part of one of these subparts takes a lifetime of study.
If you like, besides talk origins there are many good sites that discuss various aspects of biological knowledge that I can give you. It would take weeks of reading to fully understand the basic principles and supporting data for evolution.
My most detailed knowledge is in invertebrates, especially Insecta and parasitology. But every biologist must know the principles of evolution to understand the big picture of how life functions and changes by interactions within its ecosystem.
One good general book you might enjoy is Darwin's Ghost. Another interesting book on a specific topic is Parasite Rex.
No, I know better than that. I was just looking for a discrete, measurable event that I could hold for discussion.
I hope you don't take this the wrong way...but I would find myself responding to you more favorably if you would stop disparaging my intelligence. You seem to take me for a creationist, which is no doubt the source of your disdain; what I am, however, is a layman with no vested interest in either direction.
You don't even see the real issue, you are so blind. Just because someone does not agree with your narrow reading of the bible does not make them wrong, nor does it make your insistence on the literal truth of Genesis even theologically sound.
First of all, nobody is claiming that "black people are a link between apes and white people." That's something you just made up from whole cloth. My point is that the frequency of the alleles responsible for human skin color has changed over time. That's called evolution. There's no presumption that some people are "more evolved" than others, or that one group of people are closer to apes than others. All humans do not share the exact same pattern of allele frequencies, however. Dark skin is favored in warmer, equitorial climates. Light skin is favored in colder climates. As far as white people evolving in Egypt is concerned, where is your evidence that this is how it happened? Isn't it possible that the people who formed the earliest civilizations in Egypt were migrants from another part of the world who had evolved lighter colored skin? Isn't it possible that the main barriers to interbreeding were cultural and sociological rather than geological? (Ie. the Egyptians considered themselves superior to the surrounding non-Egyptians)
HMmmm...
smooth skincolor gradient; 5 sharply defined races....
I guess I'll not mutate; for my skin doctor said to avoid sun.... skin cancer problems.
Oh wait!!!
I guess I WOULD mutate then!
Wait!
I thought E folks said these came AFTER Dino!?
DANG!
Just like them famous moths!
Ok now....
Which is it?
Evolution or NOT?
Does this mean that Blacks living in Minneapolis will have lighter and lighter descendants?
Elsie IS in shape!
(Round is a shape.)
Oh I think that 'science' does pretty well without ME!
(I'll say nothing about others who are OBVIOUSLY so much more learned than I.)
They DID?
Well....
Just WHO gave them DIFFERENT names???
So what?
(Ie. the SOMEBODYS consider themselves superior to the surrounding non-SOMEBODYS)
Oh...
Did I say SOMEBODY?
I meant EVOLUTIONIST
So what?
So, that's a possible explanation of why the Egyptians didn't interbreed with the darker-skinned people in the surrounding areas, which was the question you asked me. This is the only coherent statement I can glean from your replies to me. The rest seem to be non sequiters. Please refrain from posting to me if you are just going to post things that have no bearing on the rest of the thread or the subject matter that we are debating. It wastes my time and the bandwith of the site, and I am not going to respond any further to any of it.
NIV Isaiah 29:13-16
13. The Lord says: "These people come near to me with their mouth and honor me with their lips, but their hearts are far from me. Their worship of me is made up only of rules taught by men.
14. Therefore once more I will astound these people with wonder upon wonder; the wisdom of the wise will perish, the intelligence of the intelligent will vanish."
15. Woe to those who go to great depths to hide their plans from the LORD, who do their work in darkness and think, "Who sees us? Who will know?"
16. You turn things upside down, as if the potter were thought to be like the clay! Shall what is formed say to him who formed it, "He did not make me"? Can the pot say of the potter, "He knows nothing"?NIV Isaiah 35:3-8
3. Strengthen the feeble hands, steady the knees that give way;
4. say to those with fearful hearts, "Be strong, do not fear; your God will come, he will come with vengeance; with divine retribution he will come to save you."
5. Then will the eyes of the blind be opened and the ears of the deaf unstopped.
6. Then will the lame leap like a deer, and the mute tongue shout for joy. Water will gush forth in the wilderness and streams in the desert.
7. The burning sand will become a pool, the thirsty ground bubbling springs. In the haunts where jackals once lay, grass and reeds and papyrus will grow.
8. And a highway will be there; it will be called the Way of Holiness. The unclean will not journey on it; it will be for those who walk in that Way; wicked fools will not go about on it.NIV Luke 4:14-19
14. Jesus returned to Galilee in the power of the Spirit, and news about him spread through the whole countryside.
15. He taught in their synagogues, and everyone praised him.
16. He went to Nazareth, where he had been brought up, and on the Sabbath day he went into the synagogue, as was his custom. And he stood up to read.
17. The scroll of the prophet Isaiah was handed to him. Unrolling it, he found the place where it is written:
18. "The Spirit of the Lord is on me, because he has anointed me to preach good news to the poor. He has sent me to proclaim freedom for the prisoners and recovery of sight for the blind, to release the oppressed,
19. to proclaim the year of the Lord's favor."
It is a FACT that males of ANY group will definitely 'mate' with females of a lower-class group.
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