|
Post by stoneage on Jul 20, 2008 11:56:56 GMT
Are you using the moving goal post defense?
|
|
|
Post by Dinotoyforum on Jul 20, 2008 12:03:14 GMT
Are you using the moving goal post defense? do you think it is? why?
|
|
|
Post by stoneage on Jul 20, 2008 12:12:13 GMT
Because you didn't directly comment on Archaeopetryx. Is it a bird? Did birds evolve from Archaeopetryx. Did Dinosaurs survive? Do you have evidence that proofs it beyond a shadow of doubt? Can you answer these questions directly?
|
|
|
Post by Dinotoyforum on Jul 20, 2008 12:33:29 GMT
Because you didn't directly comment on Archaeopetryx. Is it a bird? Did birds evolve from Archaeopetryx. Did Dinosaurs survive? Do you have evidence that proofs it beyond a shadow of doubt? Can you answer these questions directly? there was no 'moving the goalposts' because your Archaeopteryx post wasn't providing evidence for any particular claim. To answer your questions, it depends how you define a bird (which is your point is it not?), that is an issue of semantics and prone to the insufficiency of taxonomy to classify objects on a continuum. So the answers to your simple questions are not simple. But I will answer the questions directly...I will not give my reasons unless you ask. Is it a bird? Yes Did birds evolve from Archaeopetryx. Archaeopteryx is a bird so the question makes no sense. Did Dinosaurs survive? Yes Do you have evidence that proofs it beyond a shadow of doubt? No Can you answer these questions directly? yes.
|
|
|
Post by richard on Jul 20, 2008 19:21:30 GMT
Did birds evolve from Archaeopetryx. Archaeopteryx is a bird so the question makes no sense. that's the point
|
|
|
Post by stoneage on Jul 21, 2008 1:20:28 GMT
Thanks for a direct response. Your previous response was kind of it depends on how you look at it. So if its not to muuch to ask why do you think Archaeopteryx is a bird specifically and do you think todays birds are it descendants? I just want to understand your point of view.
|
|
|
Post by Dinotoyforum on Jul 21, 2008 10:40:31 GMT
I think Archaeopteryx is a bird because it is classified as a bird - and it really is that simple (see beautiful diagram below) (the specific 'bird' characters are irrelevant for this discussion). It is a meaningless question anyway - look at the diagram below - where would YOU draw the line? Everything merges into everything else. Here is a thought experiment: Imagine a circle. now imagine the circle morphing into a square- at one point it is half square/half circle right? OK, so would you classify that intermediate shape as a circle or a square? In reality, It's both and neither. But in the world of shape classification a line must be drawn somewhere. And so it is with the classification of life. Classifications are arbitrary: just a way of organizing life (and everything else) so that we can talk about it easier. Are todays birds directly descended from Archaeopteryx? Well, evolution is a branching tree, not a ladder, so to be a direct ancestor of modern birds, Archaeopteryx must sit on the main trunk of the evolutionary tree. This is not possible to determine (we can only determine relative relationships), but probably not because there is so much more 'branch' than 'trunk'. I kept it full size for clarity.
|
|
|
Post by tomhet on Jul 21, 2008 16:13:01 GMT
^^^ *notices new sig caption* Careful A., you don't want to end up with your leg chewed
|
|
|
Post by stoneage on Jul 21, 2008 23:15:21 GMT
Who makes or decides the classification of animals.
|
|
|
Post by Libraraptor on Jul 22, 2008 8:46:30 GMT
It´s not carved in stone forever, noone "makes" the classification, it´s rather a process many scientists are concerned with. There is no board of old men on old desks in a dusty library acerbly deciding "This and that is a bird, that is no bird, that is a mammal, that is a fish. This is the decision." What you are shown above is a so called cladogram, a helpful tool that´s a product of comparing many features of each animal with each other. So you can be relatively sure where to put a certain animal. I´have got a book called "Mesozoic birds. Above the heads of dinosaurs", and besides of interesting facts and figures it´s full of boring charts comparing qualities such as "humerus longer than 2/3 of leg". Then you see Theropods from Allosaurus to Archaeopteryx and a "1" for yes, a "0" for no and a "-" for not known. Computers do most of that work, the scientist feeds them with the features of the animals he wants to compare and as a product you´ve got a prototype of a cladogram. The biggest misunderstanding of such a cladogram has already occured much often. It´s drawing the conclusion that, for example, Eoraptor descended from Marasuchus. One basic thesis of cladograms is that the real common ancestors are probably not among the animals that have already been found and one can only compare the relative affinities of groups (see above, "branches" vs. "trunks"). Some "birds are not dinosaurs" - guys have pushed their amateur research to perfection by always repeating "Birds cannot have evolved from dromaeosaurs because both lived a the same time. How come?" Really nice question. A question showing they haven´t learned anything at all. I have to admit that sometimes the interpretations of the evidence has been perverted: Some palaeontologists even go as far as regarding even Dromaeosaurus as birds that have already become unable to fly again. That would explain the certainly over-the-top paintings of artists like Louis V. Rey. But let´s face it: we will never be able to see a real raptor alive, as much as we might try to project that wish on modern birds If an eagle could speak it woud say: "d**n it, why aren´t scientists happy of me being an eagle and see my true beauty as a bird, I really hate my ancestors for that part of the heritage... Isn´t it better to be a perfect bird than to be a "strongly modified dinosaur?"
|
|
|
Post by Dinotoyforum on Jul 22, 2008 10:38:15 GMT
Who makes or decides the classification of animals. I will presume that's a rhetorical question, but I'm not sure what your point is (Libraraptor is right). OK - I'm turning the tables now. I'm interested in your point of view Stoneage...how do you answer the following questions... Archaeopteryx - is it a bird? Did birds evolve from Archaeopetryx. Did Dinosaurs survive? Do you have evidence that proofs it beyond a shadow of doubt? Can you answer these questions directly?
|
|
|
Post by stoneage on Jul 22, 2008 21:49:58 GMT
;D Is Archaeopteryx a bird? I guess it depends on where you draw the line. The dinosaur features seem to outnumber the bird features about 10 to 1. However if I saw it I'd probably associate it with birds. Did it evolve into bird? Some say that birds existed before Archaeopteryx but I don't know of any proof. If they did then I think it would be like Neanderthal and Homo Sapiens, Common ancester, Neanderthals died out ,Home Sapiens lived on. If this is the case then birds did not evolve from Archaeopteryx but have a common ancester. I have not had a science course since High School and am not an expert. I haven't studied Anatomy. Its just when someone makes an absolute conclusion I feel a need to question it sometimes. I've read some of your work and was impressed. I ask questions because compared to me you are an expert and I hope to learn from it. Basically I'm not a 100% sure about these questions. I hope this is a direct enough answer for you.
|
|
|
Post by stoneage on Jul 22, 2008 21:53:45 GMT
No I can't prove any of the above beyond a shadow of a doubt. I guess when I asked that question I should have left out the "beyond a shadow of a doubt" part.
|
|
|
Post by Libraraptor on Jul 23, 2008 8:35:38 GMT
The dinosaur / bird relationship question is nearly as old as dinosaur palaeontology itself. We simply do not know if Archaeopteryx is really the common ancestor of every modern bird, since evolution is merely a brush that a tree with a central trunk (I like that metaphor!). If you asked me, it´s not likely, since fossilization didn´t occur that often and why should it of all things have occured with the species we are looking for? I like the imagination of some early featherd dinosaurs and birds watching the screen of a future time machine shaking their heads and laughing about mankind still looking for that common ancestor needle in a haystack, playing hide and seek. To me searching for that needle thus is the wrong approach, I prefer the cladogram approach. You heard of birds before Archaeopteryx? Then you probably came in touch with that Protoavis debate. A palaeontologist named Sankar Chatterjee once thought he had found a Triassic bird, and suddenly some other palaeontologists jumped on that train and drew the conclusion that when there were Triassic birds, then they simply cannot have evolved from dinosaurs. The point is that the evidence is rather unsatisfying. The bones Chatterjee found in Texas can be put together as one likes them to fit - obviously the way they best fit their argumentation. If your opinion is birds didn´t evolve from dinosaurs but from some earlier Permian / Triassic Archosaurs you certainly can interpret the bones that way. But hey, let´s face the facts: The evidence for a Triassic bird is bad, Chatterjees reputation among scientists is not very good (he sometimes simply doesn´t work scientifically correct), and as far as we know, Archaeopteryx still is the oldest known bird.
|
|
|
Post by Dinotoyforum on Jul 23, 2008 11:44:24 GMT
;D Is Archaeopteryx a bird? I guess it depends on where you draw the line. The dinosaur features seem to outnumber the bird features about 10 to 1. However if I saw it I'd probably associate it with birds. Did it evolve into bird? Some say that birds existed before Archaeopteryx but I don't know of any proof. If they did then I think it would be like Neanderthal and Homo Sapiens, Common ancester, Neanderthals died out ,Home Sapiens lived on. If this is the case then birds did not evolve from Archaeopteryx but have a common ancester. I have not had a science course since High School and am not an expert. I haven't studied Anatomy. Its just when someone makes an absolute conclusion I feel a need to question it sometimes. I've read some of your work and was impressed. I ask questions because compared to me you are an expert and I hope to learn from it. Basically I'm not a 100% sure about these questions. I hope this is a direct enough answer for you. Sounds like we are on the same page after all In reality, the answer to all your questions was "yes and no" or "it depends", that's why I thought I'd ask you in return. "I guess it depends on where you draw the line" - exactly! Your comments about common ancestors - exactly how I would explain it. "when someone makes an absolute conclusion I feel a need to question it sometimes." - Sounds like you are a scientist to me. Science comes to verdicts (much like a court of law does), and they are often very well supported by evidence (much like a court of law is). This is the case with feathered dinosaurs. But this is only absolute in a scientific sense - not a philosophical one. Just as in law, science uses evidence reach a satisfactory "verdict". If your level of evidence is impossibly high, all the criminals go free and in this case what would be the point of a court of law in the first place? Similarly, if your level of evidence is impossibly high in science, what would be the point of science in the first place? The anti-dino-bird people (the ones that don't admit that aesthetics is a major factor in their hatred for these creatures) try to have their cake and eat it. They redefine what evidence is deemed sufficient, placing the level of evidence so high that the criminals go free so to speak. This voids the whole scientific system, that is, to come to the most likely 'verdict' based on the available evidence. Simultaneously, they lower the level of scientific evidence required in the opposite direction, even resorting to non-scientific evidence, logical fallacies, and simple paranoia. The playing field is not level. "beyond a shadow of a doubt" was indeed the key phrase - in fact - I thought you were trying to trip me up with that, which is why I so adamantly said 'no'. Glad you like my work by the way - it's amazing how little feedback I typically get regarding publications. Its nice to know someone is checking it out
|
|
|
Post by stoneage on Jul 23, 2008 21:37:56 GMT
I didn't mean to come on like a prosecutor.
|
|
|
Post by thagomizer on Jul 23, 2008 22:21:55 GMT
That's right...And then there's to consider one thing:birds FLY,something that no dinosaurs did; Microraptor and Rahonavis probably did. Archaeopteryx may or may nor have, but dromaeosaurids were better adapted for flying than Archaeopteryx was. At this point there's probably better than 50/50 chance that Velociraptor evolved from a flying ancestor. Would that make it a flightless bird if confirmed? Why or why not?
|
|
|
Post by stoneage on Jul 23, 2008 23:06:34 GMT
I thought Microraptor glided rather then flew, either way its not certain. Good luck confirming a flying ancester for velociraptor.
|
|
|
Post by thagomizer on Jul 30, 2008 10:25:47 GMT
I thought Microraptor glided rather then flew, either way its not certain. Good luck confirming a flying ancester for velociraptor. It's less certain for Archaeopteryx than for Microraptor. If Archie could fly, Micro definitely could. If Micro couldn't, Archie definitely couldn't. Chatterjee 2007 studied Microraptor gliding, parachuting, and flying ability, and found Micro was capable of clumsy level flight. Full paper here: www.pnas.org/cgi/reprint/0609975104v1.pdfThe most primitive dromaeosaurs are the most bird like. The most primitive troodontids are the most bird-like. The most primitive birds are the most primitive deinonychosaur-like. The common ancestor of all three groups would have been something almost identical to Archaeopteryx, Microraptor, or Sinovenator (which are all pretty identical to begin with). I think the idea that tiny, flying or near-flying critters evolved into big flightless dromies and big flightless troodonts is more likely than the idea that small, Archaeopteryx-like dromies and troodontids not only evolved multiple times, but evolved flying and gliding multiple times. Flying is harder to evolve than flightlessness, just look at modern birds. Almost every single group has multiple flightless species. Not to mention, flightless species tend to lose traits relating to flight, which would mess up cladistic analysis and make flightless species look more primitive than flying species. Which is exactly what you see in cladistic studies of early birds and deinonychosaurs.
|
|
|
Post by stoneage on Jul 30, 2008 15:10:32 GMT
I agree with your general thought. I just want to see the little flying critter.
|
|