Posted on 10/24/2002 1:32:37 PM PDT by vannrox
Scientist Says Ostrich Study Confirms Bird "Hands" Unlike Those Of Dinosaurs CHAPEL HILL -- To make an omelet, you need to break some eggs. Not nearly so well known is that breaking eggs also can lead to new information about the evolution of birds and dinosaurs, a topic of hot debate among leading biologists. Drs. Alan Feduccia and Julie Nowicki of the University of North Carolina at Chapel Hill have done just that. They opened a series of live ostrich eggs at various stages of development and found what they believe is proof that birds could not have descended from dinosaurs. They also discovered the first concrete evidence of a thumb in birds. A report on their investigations will appear online in the August issue of Naturwissenschaften, the top German biology journal, and soon afterwards in the print edition. "There are insurmountable problems with that theory," he said. "Beyond what we have just reported, there is the time problem in that superficially bird-like dinosaurs occurred some 25 million to 80 million years after the earliest known bird, which is 150 million years old." Editor's Note: The original news release can be found at http://www.unc.edu/ news/newsserv/research/feduccia081402.htm
Note: This story has been adapted from a news release issued by University Of North Carolina At Chapel Hill for journalists and other members of the public. If you wish to quote from any part of this story, please credit University Of North Carolina At Chapel Hill as the original source. You may also wish to include the following link in any citation:
"Whatever the ancestor of birds was, it must have had five fingers, not the three-fingered hand of theropod dinosaurs," Feduccia said. "Scientists agree that dinosaurs developed 'hands' with digits one, two and three -- which are the same as the thumb, index and middle fingers of humans -- because digits four and five remain as vestiges or tiny bumps on early dinosaur skeletons. Apparently many dinosaurs developed very specialized, almost unique 'hands' for grasping and raking. "Our studies of ostrich embryos, however, showed conclusively that in birds, only digits two, three and four, which correspond to the human index, middle and ring fingers, develop, and we have pictures to prove it," said Feduccia, professor and former chair of biology at UNC. "This creates a new problem for those who insist that dinosaurs were ancestors of modern birds. How can a bird hand, for example, with digits two, three and four evolve from a dinosaur hand that has only digits one, two and three? That would be almost impossible."
The new work involved microscopic examination of early skeletal development in ostrich embryos, he said. Nowicki, who received her doctorate in biology at UNC last year, and he found the critical period for major features of the skeletons of primitive birds like ostriches to appear occurred between days 8 and 15 of those birds' 42-day growth inside eggs.
The beginnings of arm bones and "fingers" begin to appear around day 8, Feduccia said. Those that would grow into the animals' thumbs, however, appear around day 14 and later disappear by about day 17.
"Because most such studies in birds have relied on embryos in the second half of development, usually at or near hatching, these studies have therefore used embryos that exhibit the form of fully developed chicks and have generated misleading results," he said. "Questions about development of bird hands were first addressed in 1821 by the famous German physician and anatomist Johann Friedrich Meckel for whom the cartilage of the lower jaw was named. But no one has produced convincing evidence for a thumb before. For us, this is very exciting."
The UNC evolutionary biologist has been a strong critic of the belief that dinosaurs gave rise to birds as some paleontologists have claimed since the 1970s. He also has been a major figure in the debate for 30 years.
Most of the bird-like dinosaurs were "looking at the meteor some 65 million years ago," he said, a reference to the giant meteor believed to have struck the Earth then and killed off all dinosaurs within a short time.
If one views a chicken skeleton and a dinosaur skeleton through binoculars they appear similar, but close and detailed examination reveals many differences, Feduccia said. Theropod dinosaurs, for example, had curved, serrated teeth, but the earliest birds had straight, unserrated peg-like teeth. They also had a different method of tooth implantation and replacement.
Findings from careful examinations of alligator and turtle embryos were consistent with those of birds, the scientist added.
Far more likely is that birds and dinosaurs had a much older common ancestor, he said. Many superficial similarities between birds and dinosaurs arose because both groups developed body designs for walking upright on two hind legs and began to resemble each other over millions of years. "It is now clear that the origin of birds is a much more complicated question than has been previously thought," Feduccia said.
http://www.sciencedaily.com/releases/2002/08/020815072053.htm
When you have made it you life's work to invent postulations out of whole cloth, covering up this little road bump is a piece of cake.
'Let us prey.....on the gullible'
OTOH, I don't know if he/she has a Ph.D in chemistry...
Old story. I was in threads on FR and jennyp's site at the time.
Apparent conflict. More data needed. Not much else to say.
You are too logical. Of course, that is what one would think. The problem is, I believe, that the opposite was asserted prior to this. IOW what was assumed about dinosaur fingers cannot be true.
Hinchliffe attempts to demonstrate, using two different lines of embryological evidence, that the digits of the avain carpometacarpus are II-III-IV, then proceeds to use this as evidence that birds are not derived dinosaurs.
The latter point strikes me as weak, since he is using embryological evidence to dispell the homologies posited by workers who are looking only at osteological evidence, while a priori accepting the homolgies these workers postulate for another group. On the other hand, part of the point of the paper is that homologies established on osteological evidence may be weaker than is often thought. In any case, if one were to accept Dr. Henchliffe's findings at face value, most parsimoniously it would simply cause us to reconsider the homologies of the theropod manus (translation: if birds' digits are II-III-IV, given the evidence, isn't it just a simpler conclusion that dinosaurs' digits were II-III-IV?).
The same would happen if, for instance, it was discovered that the little toe of the horse became the single hoof.
You should also understand that Dr. Alan Feduccia is a severe critic of the now orthodox bird-dino connection.
And they call this science!?! A real scientist would just give up already.
[/Head-in-sand creationist mode]
Proof of Incompetent Design!!
This was asserted for many years about humans, but has been proven false.
Guess this isn't a point for creationists after all. Whoops.
Funny way evos have of dismissing evidence. So long as someone does not accept it, it does not count. The point is that evolutionist assumptions keep being discredited. The missing links keep getting pushed back further and further because they keep getting disproved. In short, the links are never found, the evidence is not there, but anyone who does not believe in evolution is a fool! Seems evolutionists are just ideologues who refuse to face the facts.
To the ideologues of evolution it is always a matter of 'more data needed'. They have been saying that since Darwin. Actually the Evidence Disproving Evolution is already overwhelming and irrefutable.
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