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Scientist says ostrich study confirms bird 'hands' unlike those of dinosaurs
University of North Carolina News Services ^ | August 14, 2002 | DAVID WILLIAMSON

Posted on 08/15/2002 7:16:36 AM PDT by forsnax5

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.

(Excerpt) Read more at unc.edu ...


TOPICS: Culture/Society; News/Current Events
KEYWORDS: crevolist; evolution; science
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Hey, birds got thumbs! :)
1 posted on 08/15/2002 7:16:36 AM PDT by forsnax5
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To: VadeRetro; *crevo_list
One of your favorite topics, sir...
2 posted on 08/15/2002 7:18:00 AM PDT by forsnax5
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To: forsnax5
Oh boy, another transitional form out the window. Gee, maybe Duane Gish is right, after all.
3 posted on 08/15/2002 7:25:41 AM PDT by far sider
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To: forsnax5
This is very interesting. Thanks. I've forwarded it to my family members, who have always been skeptical of the "birds descended from dinosaurs" theory."
4 posted on 08/15/2002 7:37:03 AM PDT by syriacus
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To: far sider
Gee, maybe Duane Gish is right, after all.

If Duane Gish is right about anything, it is only by pure coincidence.
5 posted on 08/15/2002 7:38:14 AM PDT by Dimensio
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To: forsnax5
My entire outlook on life will be forever altered.
6 posted on 08/15/2002 7:45:18 AM PDT by HEY4QDEMS
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To: syriacus

J. Alan Feduccia (UNC web page)

Unanswered question department: Did the earliest birds have Tarheels?

7 posted on 08/15/2002 7:48:07 AM PDT by syriacus
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To: forsnax5
But . . . I thought this was settled. It 's a fact. We have proof . . .
8 posted on 08/15/2002 8:07:13 AM PDT by Timmy
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To: Dimensio
This would seem to confirm that the embryos recapitulate evolutionary descent. (At least somewhat.) Like the jawbones of mammals becoming earbones or gills becomming vocal chords.
9 posted on 08/15/2002 8:22:07 AM PDT by Doctor Stochastic
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To: forsnax5
Feduccia gets a little "out there" in his insistence that birds and dinos are siblings, not child and parent. Here's what he's trying to make go away:

Fig. 1: Archaeopteryx Fig. 2: Deinonychus
Fig. 3: Hoatzin chick Fig. 4: Hoatzin adult
That's Archaeopteryx, the theropod dinosaur Deinonychus, and a modern bird (Hoatzin) that as a juvenile has a "throwback" clawed forelimb similar to fossil early birds but grows out of it to become a flying adult.

From the article:

"Whatever the ancestor of birds was, it must have had five fingers, not the three-fingered hand of theropod dinosaurs," Feduccia said.

The standard reptilian forelimb has five fingers, of course. Theropods evolved to lose two. Most scientists think birds simply inherited this same manus. In fact, this similarity was one of the lines of evidence that suggested a dinosaur ancestry for birds in the first place.

"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.

I can't tell where the problem is. Maybe the observation of which fingers are lost on the dinosaur is wrong.

"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."
Or maybe Feduccia is seeing what he wants, not what is there. I can't tell where the problem is, but it's unlikely that the figure above is just a misleading coincidence.
10 posted on 08/15/2002 8:24:31 AM PDT by VadeRetro
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To: VadeRetro
Or maybe Feduccia is seeing what he wants, not what is there.

Who knows. Not being a subscriber, I can't see the full the article.

11 posted on 08/15/2002 8:36:37 AM PDT by balrog666
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To: balrog666
??? I've never subscribed to UNC News Service, but I'm getting the full article, which is only a few paragraphs.
12 posted on 08/15/2002 8:39:58 AM PDT by VadeRetro
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To: forsnax5
To keep the debate about the origin of birds in perspective, bear in mind that whether birds descended from dinosaurs (the dominant view) or whether they evolved from thecodonts (Feduccia's view) this does not change anything about the relationships of living organisms.

If birds evolved from thecodonts, so did the dinosaurs, and all other archosaurs ("ruling reptiles") including Crocodilians, which are the last surviving archosaurs, and all this happened long after archosaurs and leipedosaurs ("non-ruling reptiles") split. Therefore, whichever theory about birds is true, crocodiles are still more closely related to birds than they are to other living reptiles.

13 posted on 08/15/2002 8:43:04 AM PDT by Stultis
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To: balrog666

Scientist says ostrich study confirms bird 'hands' unlike those of dinosaurs

By DAVID WILLIAMSON

UNC News Services

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.

"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."

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. 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.

"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."

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.

- 30 - Note: Feduccia can be reached at (252)-438-6545 (late mornings or late afternoons) Aug. 15th and 16th.

Next week: (919)962-3050; home: 919-942-3377 or feduccia@bio.unc.edu for a photograph of the embryo.

14 posted on 08/15/2002 8:45:35 AM PDT by VadeRetro
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To: forsnax5
"It is now clear that the origin of birds is a much more complicated question than has been previously thought," Feduccia said.

Not really. Unless, of course, he's an atheist.

15 posted on 08/15/2002 8:45:44 AM PDT by NYer
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To: forsnax5
Rather tough luck for for the unhatched ostriches.
16 posted on 08/15/2002 8:47:34 AM PDT by beGlad
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To: VadeRetro
??? I've never subscribed to UNC News Service, but I'm getting the full article, which is only a few paragraphs.

Oops, I meant the full article in the online edition of Naturwissenschaften.

17 posted on 08/15/2002 8:54:51 AM PDT by balrog666
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To: balrog666
Ich kann nicht so gut Deutsch lesen anyway.
18 posted on 08/15/2002 9:10:14 AM PDT by VadeRetro
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To: VadeRetro
I can't tell where the problem is, but it's unlikely that the figure above is just a misleading coincidence.

Your fossil diagrams are (probably) adult creatures. The premise of the article seems to be that it's not possible to determine which of the basic five "fingers" have developed in adult birds by looking at adult skeletons.

The hoatzin adult is an interesting example of rather dramatic changes in the life cycle of the bird. Reviewing the two skeletons as fossils a few million years from now, it would be difficult to see the actual relationship.

If what the article claims is true, it would appear that the later examples of feathered dinos were a second, never completed path to feathered flight.

19 posted on 08/15/2002 9:19:47 AM PDT by forsnax5
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To: forsnax5
If what the article claims is true, it would appear that the later examples of feathered dinos were a second, never completed path to feathered flight.

The later feathered dinos are often interpreted by the "sibling relationship" (birds and dinos from a common ancestor) crowd as bird descendants going back into flightlessness. The error bars in the dates are large enough that the only clear "flyer" is Archaeopteryx at about 150 million years ago.

Archaeopteryx without the feathers looks like a fairly ordinary dromaeosaur, anyway. Much of the argument is about where you draw the line between what's a dinosaur and what's a bird.

20 posted on 08/15/2002 9:39:29 AM PDT by VadeRetro
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