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.
To Darwin the glory. He made his prediction 146 years ago before there were many examples in the fossil record at all.
If he was, as some claim, a charlatan, he was the most amazingly lucky charlatan of all time.
The hoaxers imagine that they get to decide what is "evidence" to support the hoax. They can't be questioned. People can't say "Rubbish! You have no authority, and you desereve no respect." The "molecular" pap and the "Look! These jawbones are similar! That proves common ancestry!" pap. That's a good thing, b/c hoaxers nasty enough and dishonest enough to try to support the evo hoax, could be causing trouble in other areas.
Yes, it is like a Ring Species group, but does not rise to the level of speciation. Interbreeding is evolution, when populations change genetic characteristics.
The alleles for dark skin are more prevalent where filtering the sun is a survival advantage. You see, since there is a selection against darker skins in the North, eventually lighter skins prevail (as long as people are living outside). Today it might not work exactly the same way since we have Vit D supplements and many people never see sunlight in the modern world.
But there was a gradiation present prior to the relatively recent historical events you cite. For instance, you might site the example of the Eskimos in Alaska. But these are a recent immigration within the last 70,000 years over the land bridge that existed in the vicinity of the Bering Strait.
It took a lot longer than that for natural selection to turn into the gradient we see. But I would bet there is selection going on for lighter skin in native eskimo populations, especially if compared to native south american populations.
The only hoax is creationists pretending they understand science.
You imagine you're like a witch doctor with a bone in his nose, who knows some chants - scientific jargon - and you can frigthen and intimidate non-scientists. "I have a degree from the Mid-Atlantic Institute of Perfidious Sophistry! You can't say my evo stuff is rubbish, unless you can describe alleles and how they function!" Nonsense. A billion rubbish hoax-supporting papers are, and amount to, - rubbish.
Saying rubbish repeatedly is not science.
Can you describe alleles and how the function?
Precisely, which, among other things, the anthracothere does not possess. Long ago, the anthracothere was tied to the hippo. Finally, someone got the computer to spit out a number and, Eureka! problem solved. That is the point I have been making all along. They evidently reassessed the previously important teeth data and added new characters which brought about a desired outcome. The blind study is used for a reason. Scientists can get the result they wish when they get to "manipulate" the data.
These teeth
Are not here
HRC belongs to a well known class of animals that the politically correct have erased the genus name from the classification roles and moved into mythical creatures.
The cross between the flesh rending raptor and the bipedal shrew.
The were previously known a harpies.
In earlier times they were sent to torment men who displeased the gods.
In their current incarnation they torment all taxpayers.
No that is not what I am saying.
It is obvious Eskimos are Asian. That migration occurred about 75000 (or more) years ago. The population of the Earth by modern humans occurred before that.
Do people really not understand that evolution involves random mutations and then the death of all non-mutated individuals and their offspring?
<< rubbish >>
It's just the way you look at it.
Never heard about recycling?
I'll take the narrow, if you please.
The worst thing that will happen will be me being wrong.
Matthew 7
13. "Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it.
14. But small is the gate and narrow the road that leads to life, and only a few find it.
It must have evolved really fast! (or did it change UNDER our ancestors fur??
Going from highest sunlight environment to lowest, Africa to Scandanavia you go from darkest skin to lightest in a gradient.
Over a years time, most any spot on Earth recieves the same amount of daytime and night.
All that sunlight grows TREES which shade the pre-humans, eh?
You guys have MISSED the obvious:
That fossil HAMMER in the picture!
The one in my garage is just like it!!!
No pressure to change, I get......
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