Scientists Say No Evidence Exists That Therapod Dinosaurs Evolved Into Birds
- Date:
- October 10, 2005
- Source:
- University of North Carolina at Chapel Hill
- Summary:
- No good evidence exists that fossilized structures found in China and which some paleontologists claim are the earliest known rudimentary feathers were really feathers at all, a renowned ornithologist says. Instead, the fossilized patterns appear to be bits of decomposed skin and supporting tissues that just happen to resemble feathers to a modest degree.
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CHAPEL HILL -- No good evidence exists that fossilizedstructures found in China and which some paleontologists claim are theearliest known rudimentary feathers were really feathers at all, arenowned ornithologist says. Instead, the fossilized patterns appear tobe bits of decomposed skin and supporting tissues that just happen toresemble feathers to a modest degree.
Led by Dr. Alan Feduccia ofthe University of North Carolina at Chapel Hill, a team of scientistssays that as a result of their new research and other studies,continuing, exaggerated controversies over "feathered dinosaurs" makeno sense.
"We all agree that birds and dinosaurs had somereptilian ancestors in common," said Feduccia, professor of biology inUNC’s College of Arts and Sciences. "But to say dinosaurs were theancestors of the modern birds we see flying around outside todaybecause we would like them to be is a big mistake.
"The theorythat birds are the equivalent of living dinosaurs and that dinosaurswere feathered is so full of holes that the creationists have jumpedall over it, using the evolutionary nonsense of ‘dinosaurian science’as evidence against the theory of evolution," he said. "To paraphraseone such individual, ‘This isn’t science . . . This is comic relief.’"
Areport on the team’s latest research appears in the Journal ofMorphology published online Monday (Oct. 10). Other authors are Drs.Theagarten Lingham-Soliar of the University of KwaZulu-Natal in SouthAfrica and Richard Hinchliffe of the University College of Wales.
Usingpowerful microscopes, the team examined the skin of modern reptiles,the effects of decomposition on skin and the fossil evidence relatingto alleged feather progenitors, also known as "protofeathers."
Theyfound that fossilized patterns that resemble feathers somewhat alsooccur in fossils known not to be closely related to birds and hence arefar more likely to be skin-related tissues, Feduccia said. Much of theconfusion arose from the fact that in China in the same area, two setsof fossils were found. Some of these had true feathers and were indeedbirds known as "microraptors," while others did not and should not beconsidered birds at all.
"Collagen is a scleroprotein, the chiefstructural protein of the connective tissue layer of skin," he said."Naturally, because of its low solubility in water and its organizationas tough, inelastic fiber networks, we would expect it to be preservedoccasionally from flayed skin during the fossilization process."
Althougha few artists depicted feathered dinosaurs as far back as the 1970s,Feduccia said the strongest case for feathered dinosaurs arose in 1996with a small black and white photo of the early Cretaceous period smalldinosaur Sinosauropteryx, which sported a coat of filamentousstructures some called "dino-fuzz."
"The photo subsequentlyappeared in various prominent publications as the long-sought‘definitive’ evidence of dinosaur ‘feathers’ and that birds weredescended from dinosaurs," he said. "Yet no one ever bothered toprovide evidence -- either structural or biological -- that thesestructures had anything to do with feathers. In our new work, we showthat these and other filamentous structures were not protofeathers, butrather the remains of collagenous fiber meshworks that reinforced theskin."
Belief in the existence of the "dino-fuzz feathers" causedsome scientists to conclude that they served as insulation, and hencedinosaurs were warm-blooded.
The researchers also examinedevidence from five independent, agreeing studies involving structuraland genetic analyses related to the "tridactyl," or three-fingered,hand, which is composed of digits 1, 2 and 3 in dinosaurs, Feducciasaid. That is the most critical characteristic linking birds todinosaurs. They found that embryos of developing birds differedsignificantly in that bird wings arose from digits 2, 3 and 4, theequivalent of index, middle and ring fingers of humans. To change soradically during evolution would be highly unlikely.
"If birds descended from dinosaurs, we would expect the same 1, 2 and 3 pattern," he said.
Currentdinosaurian dogma requires that all the intricate adaptations of birds’wings and feathers for flight evolved in a flightless dinosaur and thensomehow became useful for flight only much later, Feduccia said. Thatis "close to being non-Darwinian."
Also, the current feathereddinosaurs theory makes little sense time-wise either because it holdsthat all stages of feather evolution and bird ancestry occurred some125 million years ago in the early Cretaceous fossils unearthed inChina.
"That’s some 25 million years after the time ofArchaeopteryx, which already was a bird in the modern sense," he said.Superficially bird-like dinosaurs occurred some 25 million to 80million years after the earliest known bird, which is 150 million yearsold."
Feduccia said the publication and promotion of feathereddinosaurs by the popular press and by prestigious journals andmagazines, including National Geographic, Nature and Science, have madeit difficult for opposing views to get a proper hearing.
"Withthe advent of ‘feathered dinosaurs,’ we are truly witnessing thebeginnings of the meltdown of the field of paleontology," he said."Just as the discovery a four-chambered heart in a dinosaur describedin 2000 in an article in Science turned out to be an artifact,feathered dinosaurs too have become part of the fantasia of this field.Much of this is part of the delusional fantasy of the world ofdinosaurs, the wishful hope that one can finally study dinosaurs at thebackyard bird feeder.
"It is now clear that the origin of birds is a much more complicated question than has been previously thought," Feduccia said.
TheUNC scientist is the author of more than 150 papers and six majorbooks, including The Age of Birds, which Harvard University Presspublished in 1980 and The Origin and Evolution of Birds, published byYale University Press in 1996.
Among other discoveries, Feducciafound by a careful examination that Archaeopteryx, the earliest knownbird and one of the world’s most famous fossils, could fly. Previously,many scientists thought the animal to be an Earth-bound dinosaur.
Hedetermined its flying ability by observing that the fossil’s feathershad leading edges significantly shorter than their trailing edges,which is characteristic of all modern flying birds. The edges offeather of birds incapable of flight, such as ostriches, aresymmetrical.
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