Feduccia claims ostrich is no dinosaur

[bh480@scn.org]

From: Ben Creisler bh480@scn.org
Here's a news release from the University Of North 
Carolina At Chapel Hill (url all one line) :
http://www.unc.edu/news/newsserv/research/
feduccia081402.htm
August 14, 2002 -- No. 425      

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.
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 <mailto:feduccia@bio.unc.edu> for a 
photograph of the embryo.