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Natural Science Forum / Biology / Paleontology / July 2007Feathered Dinosaurs - authenticity tests?
[Apologies if this is a double post - connection crashed] I know nothing about feathered dinosaurs, but to my eye the feathers seen in photographs look as though they could have been painted. Obviously this possibility has been considered at length and discarded. What authenticity tests have been applied to the feathers on which fossils where? Carbon-14? pH? Adhesion to substrate? My incomplete understanding is that there are 15 feathered dinosaurs, all from China (all from Liaoning?), of at least 8 different theropod families. The only evidence from outside China that I know of is some filamentous marks on a dinosaur trackway in the USA. There are at least three similar theropods, one each from Germany, Brazil and Spain, where the skin impressions do not show feathers. Another worry is that the date of Archaeopteryx at 150-148 MYA is older than all 15 of the feathered dinosaurs, despite that fact that it has more advanced feathers than all 15. Am I right in assuming that Confuciusornis at 120-150 MYA confirms Archaeopteryx as the most likely direct ancestor of birds? > [Apologies if this is a double post - connection crashed] > [quoted text clipped - 3 lines] > discarded. What authenticity tests have been applied to the feathers > on which fossils where? Carbon-14? pH? Adhesion to substrate? Carbon-14 tests are useless for any material older than about 40,000 years. You date such ancient fossils by examining the stratigraphic setting in which they are found. If they are found in volcanic ash deposits, they can be radiometrically dated. > My incomplete understanding is that there are 15 feathered dinosaurs, > all from China (all from Liaoning?), of at least 8 different theropod [quoted text clipped - 9 lines] > Confuciusornis at 120-150 MYA confirms Archaeopteryx as the most > likely direct ancestor of birds? Why is this a problem? No one is saying that these dinosaurs are birds. Archaeopteryx is a bird. Why is it a problem that these feathered dinosaurs have less advanced feathers than Archaeopteryx? It would need more advanced feathers since it most likely flew. Whereas I've seen no evidence that these feathered dinosaurs ever acheived true flight. George George "George" <george@yourservice.com> wrote in message news:Ni2ii.3966 > Why is this a problem? No one is saying that these dinosaurs are birds. > Archaeopteryx is a bird. Why is it a problem that these feathered > dinosaurs have less advanced feathers than Archaeopteryx? It would need > more advanced feathers since it most likely flew. Whereas I've seen no > evidence that these feathered dinosaurs ever acheived true flight. not even fly onto a low tree limb like a chicken? > "George" <george@yourservice.com> wrote in message news:Ni2ii.3966 > [quoted text clipped - 5 lines] > > not even fly onto a low tree limb like a chicken? If you have evidence that they could do that, I'm all ears. George > Why is this a problem? No one is saying that these dinosaurs are birds. Either feathers evolved completely independently in birds and theropods or they didn't. But in the first case asymmetric feathers (believed to be used for flight) evolved twice completely independently. And in the second case many different types of primitive feathers survived independently for some 90 or so million years. The pattern of feather development on the 8 (or more) different theropod families doesn't make sense. On authentication: On the fossil that was a famous fake (Archaeoraptor), the fake was fist spotted when half of it it was identified by a keen eyed researcher as the same as another fossil, then it was checked out with infra-red and computerized tomography. Perhaps similar tests have been done on some of the the other fossils. > Carbon-14 tests are useless for any material older than about 40,000 years. Which is why they would pick up any glue or charcoal added after excavation. <David.Paterson@csiro.au> schrieb: > My incomplete understanding is that there are 15 feathered > dinosaurs, all from China (all from Liaoning?), of at least > 8 different theropod families. The only evidence from outside > China that I know of is some filamentous marks on a dinosaur > trackway in the USA. A couple of links about dinos, birds, and feathers. http://www.augos.com/temp/Temp_Dino_Bird.html Regards, Joachim > [Apologies if this is a double post - connection crashed] > > I know nothing about feathered dinosaurs, And yet you feel qualified to assume that the paleontologists who do know something about them are idiots. Why is this? > but to my eye the feathers > seen in photographs look as though they could have been painted. > Obviously this possibility has been considered at length and > discarded. What authenticity tests have been applied to the feathers > on which fossils where? Carbon-14? pH? Adhesion to substrate? All you have to do is look at the actual specimen rather than a photograph, and you can tell it's not painted. There are also multiple specimens, found at different times, of some species, yet their feathers look identical. And they have microscopic structure, hardly likely to have been painted. > My incomplete understanding is that there are 15 feathered dinosaurs, > all from China (all from Liaoning?), of at least 8 different theropod > families. The only evidence from outside China that I know of is some > filamentous marks on a dinosaur trackway in the USA. All the feathered, non-avian theropods known are from Liaoning, as far as I know. Feather preservation requires special, rare conditions. Is this surprising? > There are at least three similar theropods, one each from Germany, > Brazil and Spain, where the skin impressions do not show feathers. Not sure what you're talking about here. Can you elaborate? > Another worry is that the date of Archaeopteryx at 150-148 MYA is > older than all 15 of the feathered dinosaurs, despite that fact that > it has more advanced feathers than all 15. Am I right in assuming that > Confuciusornis at 120-150 MYA confirms Archaeopteryx as the most > likely direct ancestor of birds? No. That would require the assumption that the fossil record is perfect, which it isn't. There is no reason to suppose that the oldest representative of a group is the ancestor of the rest, unless the record is perfect. Nor is the presence of more primitive featues in younger animals a cause for concern, unless you think that the existence of a living platypus is a problem for Eocene whales. If you want a reference specifically on birds, try Brochu, C. A., and M. A. Norell. 2000. Temporal congruence and the origin of birds. J. Vert. Paleont. 20:197-200. |
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