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Ear-splitting discovery rocks mammal identity [Evolution, platypus]
news@nature.com ^ | 10 February 2005 | Roxanne Khamsi

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.


TOPICS: Culture/Society; Miscellaneous; Philosophy
KEYWORDS: crevolist; cryptozoology; evolution; palaeontology; platypus
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To: Fester Chugabrew
I reckon you could scientifically predict the outcome of the latest Superbowl game, too. Congratulations.

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.

221 posted on 02/13/2005 6:14:07 PM PST by VadeRetro
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To: TalonDJ

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.


222 posted on 02/13/2005 6:27:13 PM PST by 185JHP ( "The thing thou purposest shall come to pass: And over all thy ways the light shall shine.")
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To: UnbelievingScumOnTheOtherSide

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.


223 posted on 02/13/2005 6:32:10 PM PST by shubi (Peace through superior firepower.)
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To: 185JHP

The only hoax is creationists pretending they understand science.


224 posted on 02/13/2005 6:33:51 PM PST by shubi (Peace through superior firepower.)
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To: shubi

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.


225 posted on 02/13/2005 6:50:13 PM PST by 185JHP ( "The thing thou purposest shall come to pass: And over all thy ways the light shall shine.")
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To: 185JHP

Saying rubbish repeatedly is not science.

Can you describe alleles and how the function?


226 posted on 02/13/2005 7:03:47 PM PST by shubi (Peace through superior firepower.)
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To: VadeRetro
And Pakicetus has fossil whale teeth, not modern whale teeth.

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.


227 posted on 02/13/2005 7:04:29 PM PST by AndrewC (Darwinian logic -- It is just-so if it is just-so)
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To: AndrewC
I'm having trouble comparing the teeth. Remind me which one is "A whale! Just a whale!" and which one is "A hippo! Just a hippo!"
228 posted on 02/13/2005 7:07:17 PM PST by VadeRetro
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To: AndrewC
And, you know, I don't think I've ever seen two more similar hip bones on a whale and a hippo before.
229 posted on 02/13/2005 7:11:45 PM PST by VadeRetro
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To: AndrewC
You may speechify the lurkers the rest of the night, counsellor.
230 posted on 02/13/2005 7:14:14 PM PST by VadeRetro
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To: VadeRetro
I'm having trouble comparing the teeth. Remind me which one is "A whale! Just a whale!" and which one is "A hippo! Just a hippo!"

These teeth

Are not here


231 posted on 02/13/2005 7:23:32 PM PST by AndrewC (Darwinian logic -- It is just-so if it is just-so)
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To: shubi
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.

What you are saying is that modern man's migration south to north was 75,000 years ago (all Black from Africa) and then migration was strictly west to east or not at all (while Blacks turned into Asians and White people, even in places as close and sunlit as Egypt where no desert barrier existed as recently as 6000 years ago) until historic times when south to north migration suddenly resumed. Does that sound rational?
232 posted on 02/13/2005 7:58:21 PM PST by UnbelievingScumOnTheOtherSide (Give Them Liberty Or Give Them Death! - Islam Delenda Est! - Rumble thee forth...)
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To: meatloaf

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.


233 posted on 02/13/2005 8:19:48 PM PST by TASMANIANRED (Certified cause of Post Traumatic Redhead Syndrome)
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To: UnbelievingScumOnTheOtherSide

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.


234 posted on 02/14/2005 3:18:15 AM PST by shubi (Peace through superior firepower.)
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To: Elpasser
Do people really not understand that evolution involves random mutations and then the death of all non-mutated individuals and their offspring?

That’s a new one. What creationist came up with the “death of all non-mutated individuals and their offspring”? Maybe I’m mistaking the intent. How long does it take for these to die off? The cockroach has been around for a long time, and has changed little in hundreds of millions of years. Mosquitoes have been around since the dinosaurs.
235 posted on 02/14/2005 3:34:36 AM PST by R. Scott (Humanity i love you because when you're hard up you pawn your Intelligence to buy a drink.)
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To: 185JHP

<< rubbish >>

It's just the way you look at it.
Never heard about recycling?


236 posted on 02/14/2005 4:13:37 AM PST by MHalblaub (Tell me in four more years (No, I did not vote for Kerry))
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To: WildHorseCrash

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.


237 posted on 02/14/2005 5:58:13 AM PST by Elsie (Heck is where people, who don't believe in Gosh, think they are not going....)
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To: shubi
Skin color is evidence of evolution.

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.

238 posted on 02/14/2005 6:03:31 AM PST by Elsie (Heck is where people, who don't believe in Gosh, think they are not going....)
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To: shubi

All that sunlight grows TREES which shade the pre-humans, eh?


239 posted on 02/14/2005 6:05:28 AM PST by Elsie (Heck is where people, who don't believe in Gosh, think they are not going....)
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To: AndrewC

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......


240 posted on 02/14/2005 6:08:08 AM PST by Elsie (Heck is where people, who don't believe in Gosh, think they are not going....)
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