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>What do you(anyone interested) think of the birds-ARE-dinosaurs concept? > >The reason I ask is because it strikes me as very "gimmicky" and most often >is used for it's buzz word value(see below). Well, no....it represents a fundamental change in the way we view taxa. The general public goes wow >and scientists get some attention payed to them and all is warm and fuzzy. You would think so, but it isn't that easy. We scientists are then forced to explain WHY birds are dinosaurs. Try explaining monophyly to a group of nonspecialists. If ease were the criterion for group membership, birds would never have been dinosaurs. (Of course, whales and bats would never have been mammals, and crinoids would never have been animals.) >But obviously birds are not dinosaurs. They may be VERY closely related and >may share a common ancestor but a dinosaur is not a bird. Actually, to paraphrase Jacques Gauthier, birds are as much dinosaurs as we are mammals. THe evidence is that strong, and if we are to recognize taxa as natural groups, then all descendents of the ancestral dinosaur must be dinosaurs. > >We don't call snakes lizards even though they are very closely related. Actually, some do - or, better yet, we call them all "squamates." We >have not gone backwards and decided to call snakes "lizards" just because >we have a better idea of their evolutionary heritage. The point is that >even though birds may have evolved from therapod dinosaurs, the fact is >that they EVOLVED into BIRDS. BIRDS. BIRDS. BIRDS. Yes. And BIRDS are DINOSAURS, TETRAPODS, VERTEBRATES, and ANIMALS. The fact that they are BIRDS does not change that. HUMANS are also PRIMATES, MAMMALS, SYNAPSIDS, and VERTEBRATES. Evolution has this habit of creating a hierarchical system of internested groups, and the fact that a group belongs to a larger, more inclusive group does not remove its individuality. > >By playing on symantics(buzz words) here the Paleontological community is >practicing BAD SCIENCE. Bad science is an incidious thing. It often comes >in the form of overly simplified ideas or images. See my comment above. I teach a dinosaur course here; it isn't a simplified idea at all. It would be far easier to simply slip back into the days of "a dinosaur is a dinosaur, and a bird is a bird." That this obscures relationships is an unfortunate side-effect of a desire for comfortable pigeon-holes. What we are trying to convey is relationships. The evidence that birds are descended from a theropod dinosaur is overwhelming. We can recognize an objective group on the basis of the last common ancestor of birds and other theropods. We still recognize birds as a group of their own, but Aves happens to belong to Dinosauria, just as it belongs to Vertebrata. > chris :::::::::::::::: Christopher Brochu Department of Geological Sciences University of Texas at Austin Austin, TX 78712 http://uts.cc.utexas.edu/~brochu/brochuhp.html gator@mail.utexas.edu
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