Posted on 09/22/2006 6:27:23 AM PDT by Tokra
The earliest known ancestor of modern-day birds took to the skies by gliding from trees using primitive feathered wings on their arms and legs, according to new research by a University of Calgary paleontologist. In a paper published in the journal Paleobiology, Department of Biological Sciences PhD student Nick Longrich challenges the idea that birds began flying by taking off from the ground while running and shows that the dinosaur-like bird Archaeopteryx soared using wing-like feathers on all of its limbs.
"The discussions about the origins of avian flight have been dominated by the so-called 'ground up' and 'trees down' hypotheses," Longrich said. "This paper puts forward some of the strongest evidence yet that birds descended from arboreal parachuters and gliders, similar to modern flying squirrels."
The first fossil of the Jurassic-era dinosaur Archaeopteryx lithographica was discovered in Germany in 1861, two years after Charles Darwin published his theory of evolution in On The Origin of Species. Since then, eight additional specimens have been unearthed and Archaeopteryx is considered the best evidence that birds evolved from dinosaurs since it had both feathers and a bird-like wishbone, along with classic reptilian features of a long bony tail, claws and teeth.
Although scientists immediately noticed feather-like structures on the hind limbs, they were dismissed as insulating body feathers that didn't play a role in the animal's flight. It wasn't until several four-winged dinosaurs in China were described in 2002 that researchers began to re-examine Archaeopteryx's legs.
"The idea of a multi-winged Archaeopteryx has been around for more than a century, but it hasn't received much attention," Longrich said. "I believe one reason for this is that people tend to see what they want or expect to see. Everybody knows that birds don't have four wings, so we overlooked them even when they were right under our noses."
Under the supervision of professor Anthony Russell, Longrich examined Archaeopteryx fossils and determined that the dinosaur's leg feathers have an aerodynamic structure that imply its rear limbs likely acted as lift-generating "winglets" that played a significant role in flight.
You really should research your beliefs before you post them as fact.
See post #113.
nice try again, dont you get tired of the propraganda failing so miserably???
From my viewpoint it is you that is spreading propaganda. I have studied many of the primary fossil skulls in grad school. I have lined them up on a desk and looked carefully at the similarities and differences. And not just the largely whole skulls, but a lot of small fragments that most folks never see.
And to call evolutionism a religion is a flat out lie. You can do better than that. (They never once passed the collection plate in one of my classes, and if that doesn't convince you that evolution is not a religion, nothing will.)
Still shooting blanks I see, and CAPITALIZING everything in your post just shows that you are irrational, and do not want to learn about real science.
The stuff you spew is so far from real science that it is pretty much ridiculous.
If you wish to learn, then learn, otherwise, please be silent, your rambling and ignorance all over the thread make you look as ignorant as you probably are.
It makes me want to cry when I see such absolute fanticism on someones part that they will lie, and lie, and continue to lie to make a point. That is exactly what you are doing, lying.
Please learn the theory, before you start popping off nonsense about what it says and what it does not say, and what it knows and what it does not know.
You are completely clueless, and it really is sad to see it.
As well as the fact you are yelling, like a crazy person.
"They never once passed the collection plate in one of my classes, and if that doesn't convince you that evolution is not a religion, nothing will."
Right on! Without a doubt the most compelling evidence.
Are you seriously claiming that fossils are a lie made by God to deceive us?! What god do you worship anyhow, Loki?
metmom: It's been done before.
A Chinese peasant did that a few years, ago (actually combined two fossils IIRC), embarrassed hell out of National Geographic, but it was caught by peer review before it did any real damage.
The only other case I'm aware of is the Piltdown fraud, which may have been committed by a scientist; nobody knows who did it.
A six foot Pteranodon with a 25 foot wingspan?
Scientists spend from 6 to 10 years and tens of thousands if not hundreds of thousands of dollars learning everything they possibly can about a subject, including the implications and logical consequences of the processes behind that subject, then spend the rest of their lives increasing not only their own but science's in general knowledge, by actively researching and developing tests based on their intimate knowledge of those implications and logical consequences, yet when those very scientists, in all likelihood years before you were born, develop a definition of transitionals, you decide to latch on to a definition expressly designed by people of your like mind to present a false image of transitionals that is much easier to refute than the scientific definition and then require the rest of the world to adopt that strawman.
What makes you believe your opinion is valuable enough that the scientists who work in the many fields related to evolution and who collectively define terms which they use on a daily basis, should adopt your obviously half thought out and mind numbingly ridiculous redefinition of what constitutes a transitional fossil?
This all coming from the person who figures birds should retain reptilian respiratory system despite the fact the demands on the system are quite different. And you call me stupid.
Since you are obviously stuck in your own little world where you can pat yourself on the back for being wrong I'll address the rest of my post to the lurkers.
One of the main concepts of Evolution is that new features are derived from already existing features which acquire new function through variation in the genome and selection forces. There is also a reciprocal to this that features acquire morphological changes because their function is changing due to selection processes. The morphological change coupled with the functional change sets up a feedback loop. And yes, feedback loops are ubiquitous in nature.
The upshot of this, contrary to some who believe themselves above the thousands of highly intelligent men and women practicing science in the related fields, is that transitionals do not exhibit partial wings, partial limbs or limbs which are half and half.
In the case of the wing, a wing at its essence is a nothing more than a modified forelimb. For the scenario of a partial limb to arise, the existing limb would have to degrade to nothing either before, during or after a completely new appendage, the wing, grows at a nearby but different location, or the limb would have to at some point be half wing and half limb (from the shoulder to elbow a wing and from the elbow to wrist a normal limb). This is baldly ridiculous on the face of it.
For the bird wing to develop from the dinosaur forelimb it would at no time be a partial wing, either in morphology or in function.
Feathers, pneumatic bones (bones with air-sacs - light and strong), and fused clavicle (wishbone - to help support the increased muscle mass) all existed in theropods before dino/birds such as Archaeopteryx took flight.
Feathered fore limbs are not half wings but are as fully functional as the limbs of any other dinosaur. To change to a semi-gliding dinosaur all that needs to happen is the membrane (skin) which normally is attached at points along the limb to move its attachment points. This is similar to flying squirrels, flying lemurs, and bats as well as those few humans who have webbed fingers and/or toes (and no, I'm not suggesting that humans could fly. I am just showing that attachment point movement happens without decreasing function). Moving the attachment point does not produce a half wing. It does however, increase the surface area of the limb giving loft when jumping.
As the membrane increases in area, the ability to glide improves. During this time increased muscle mass and deepening chest would develop simultaneously.
Note: At this point the gliding dino does not need the modified respiratory system. Archy probably did not have an avian respiratory system yet apparently could fly.
After the maximum lift surface has been acquired, again through no steps that leave the dino/bird with partially formed or non-functional wings, the only way to increase lift is to lengthen the limbs, or in the case of bats and birds, the fingers.
There is nothing prohibitively costly in any of this.
The change from a gliding wing to a flying wing can be accomplished without experiencing a non-functional or partially non-functional half wing. To suppose that a half wing is necessary at any point is nonsense.
This needs to be repeated - At no time in the evolution of the reptilian (dinosaurian - theropod) fore limb to avian wing does the evolving limb experience a period of non-functionality or 'half' existence. The belief that the transitionals between theropods and aves must exhibit a half wing is utter nonsense.
[Thunderous applause!]
You wouldn't recognize a transitional if it smacked you in the face.
All you've done is conjure up a fairytale idea of what a transitional should look like, despite your abysmal knowledge of the implications of evolution on the morphology of species, with the express purpose of choosing a definition which cannot be satisfied. If the only way you can win an argument is through redefinition, I suggest you not bother - it makes you look disingenuous.
The definitions we use for transitional were developed a very long time ago and were based on the understanding of the tenets of the SToE. Yours were based on the need to devalue transitional fossils and based on ignorance of the implications of the SToE.
BTW, a number of those quotes you posted, including the one from Gould, are nothing but quote mines. They are misrepresentations of what the authors believed and actually said.
If you really want to play the 'appeal to authority' game, each quote you come up with, that isn't a quote mine, can be surpassed in number by quotes that claim transitional status for many fossils.
Good information. Thanks!
You don't tithe to Darwin Central?!
The order of the fossils is determined by the dates of the strata they are found in - it is not arbitrary.
Wow, my first TA.
I have goose bumps.
(which are a remnant from when we had fur, no less)
Ichneumon sets a tough standard.
ARCHIVAL QUALITY.
[hiatusmode]
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