Theropods and Birds showing a change in kinds

We briefly overlooked humanid evolution with huntard a bit earlier I believe. Since it wasn't in the subject I referred the book 'bones of contention'.You ask what ese is needed. For similarities to be conclusive proof of common descent, you need to be able to prove that all other options aren't possible. One of those options is convergent evolution. You need to find a physical criteria that can be observed that show convergent evolution took place and not common descent. Dr. Adequate said earlier that convergent evolution causes only superficial ressemblance but no in depth similarities. I have a hard time accepting this idea as valid, so maybe if it could be explained in detail and how a criteria for convergent evolution can be clearly stated out of this.

This is a bit off-topic, but I'll give a brief answer anyways. Creationist don't solely have evidence against evolution, they also have evidence for creation.Now, in the case of evidence against evolution, sure creationists uses them a lot. And they are not necessarily proof of a 6000 year old creation of the world obviously. Rather, arguments against the evolution of species simply becomes evidence for the statistity of species (in which of course the biblical creation fits well obviously)Now, I think you misunderstood my statement there. I wasn't saying you have to disprove all other options in order to prove common descent. I was saying that if you want similarities alone to be sufficient proof for common descent, then you have to disprove all other options. Of course, anyone with some knowledge of philosophy of science will realise that this is an impossible feat to accomplish, and therefore similarities are unsufficient by themselves to prove common descent. I meant this sentence as: In a given situation, is thee a way to show that common descent took plce and not convergent evolution? Not the best example of convergent evolution, I prefer Taq's example with duck and platypus bills. Although everything I will say on that issue would probably apply to your example.

Exactly the point I wanted to make. It would be impossible to disprove every other option to explain the similarities. I was just saying that if you wanted to use similarities as sufficient proof for common descent, this would have to be done. Since it cannot be done, then similarities can never be sufficient proof of common descent. This is just another path I took to explain the same thing I had previously in the thread, but new people had jumped into the discussion and asked why I didn't find similarities to be compelling proof of common descent. Excellent example. So you would agree that convergent evolution will only provide superficial similarities, never in depth ones ? I agree this would be expected. However, recently I came across a counter-example where convergent evolution had caused the similarities to be right down to the molecular level. It is about the sonars of bats and dolphins which acquired the same DNA for this characteristics through convergent evolution:http://www.sciencedaily.com/...ases/2010/01/100125123219.htm

I agree completely. This is what I'm trying to say all along.Of course, those who have been saying that there isn't only one line of evidence will have understood this as well. It's more for those who ask: ''why doesn't this similarity between this one and that one convince you ?''

A lot of the criticism I read yesterday by Alan Feduccia were very interesting and I think a little research on what he has to say would be helpful. I'll try to find some bits to put here.I think the main logic in his discours is this: if feathers are so perfectly optimized for flight, why would anyone suggest they in fact evolved for endothermy (for which they are a sub-optimal structure, both in efficiency and in production cost) I had this information from prof. John Ruben of OSU (who was involved in the previous research who held that birds do not descend from dinosaurs): Maybe are there some very old birds found in the fossil record, but since they don't fit that well with the dinosaur-to-bird theory you don't hear as much about them as Archaeopteryx.

I disagree. You have 'proof beyond reasonable doubt'. In other words, some things can be proven to a point where any doubt you can have will be unreasonable, illogical. This isn't absolute proof, but it isn't no proof at all either.If you doubt that this is the case, just look at our law system and how courts prove someone guilty or innocent. Do you think they ever obtain absolute proof ? Of course not, but it doesn't mean they send people in jail with no proof at all. They prove people guilty 'beyond reasonable doubt'. Of course sometimes they do mistakes, but this is simply a side-effect of being unable to provide absolute proof. I'm afraid I don't find transitional fossils to be compelling evidence at all.AbE. I meant here to say that the concept of transitional fossils is good, but that the current evidence in it is what I do not find compelling. Isn't the coding of a complete structure as complex as a sonar more then just 'a couple of mutations here and there' and is in fact at the genome level. Maybe I guess. But my point was that if convergent evolution can produce structures in two independant species that are the same even at the DNA level, then there is no way to know if it couldn't have done the same with these introns you are talking about. (I have basic knowledge in biology, probably equal to first year university stuff)Edited by slevesque, : No reason given.

Yeah sorry, I misexpressed myself in that sentence. I wanted to say that I don't find the current actual transitional fossils to be compelling, not the general concept of transitional fossils.

There exists no half dinosaur/half bird fossils. And I have already mentioned that birds appear before their supposed ancestors in the fossil record, and probably before the vast majority of the supposed transitional fossils.Add to that the fact that there are a lot of fake dinosaur-bird fossils out there coming from china as per Alan Feduccia, and it seems that me skeptical is a justified and rational position.

Hi ZM,Yes a very good question at that. When I talk about fossils and how they relate to the ToE, I will assume the ages assigned to them in order to find a discussion ground to focus on the topic.Because if I had to come in and say ''well I think the dates are wrong anyways'', we can all see that the subject would quickly change to radiometric dating etc. etc.

I think it is evidence of a creator, but not proof. If the fossil record had really shown what was predicted of it, then I would have found this very compelling. However, the only model it does fit is the Ad Hoc explanation of ponctuated equilibrium.Also, when the field of population genetics started back in the 50's, it opened up new ways to verify the ToE and in my opinion it only showed how it is impossible on a theoretical level. (see 'genetic entropy' by Sanford) I'm sorry to say it is beyond my knowledge since I don't even know what introns are. (or I do, but I don't know the french word for them)

You gave an example of a bird that dates after the therapods. This is not surprising.What I am saying is that there are birds found before the therapods, and so whatever whatever link between the two is found after that does not explain how those earlier birds came to be in the first place.

Hi caffeine, Ever seen baby ostriches covered with downy feathers ? Quite cute right, but now imagine it getting all wet. It will die of hypothermia within minutes if it's mother doesn't heat it up. For a species to be covered by such a structure for endothermy would be extremely maladaptive, to the point of being harmful.And of course, no dinosaurs are found with downy feathers. They are either found with 'dinofuzz' or with true feathers which have a central rachis, etc. In fact, the dinofuzz is found not only on therapods, but also on icthyosaurs, pterosaurs and ornithischian dinosaurs. In none of these cases are they related to feathers, and there is nothing to suggest then that this should be the case with therapods. I couldn't tell you. Contacting him directly to ask him might be the onl way of knowing what he meant.Until we find any support for the claim I'll stop saying it Convergent evolution can do marvels. Exactly the same sonar structure up down to the genome level in dolphins and bats, for example.

Hi Dr.A, Yeah I have read some counter-quotes by Feduccia when searching a bit yesterday. I think it is fairly obvious thatwhat happened to him is the same that happened to Gould. He thought of a great alternative to the commonly accepted theory and started out in fanfare trying to promote it, with big claims etc. Of course, when some of those claims were picked up by creationists it hurt his reputation quite a bit, and to claim it back he stepped down a notch on his claims and even contradicted himself on some occasions, such as here. (which was an email answer to a question by a layman, I believe right ?)In any case, he contradicts himself. It's normal with humans

Did you read the interview with Feduccia I posted earlier ? He says that there are loads of fake fossils out there. Obviously, if they were easy to spot they wouldn't be 'out there'.Or do you think only archaeoraptor was fake and all the others were legit ?

Don't worry, my intention is not to ignore evidence.But in the case of fossils, you have either dinosaurs with feathers, but aside from that are completely dinosaurs. And birds with all the characteristics of birds (perching bird in the case of archaeopterix) with some reptile features like teeth if I remember correctly (and teeth isn't really a uniquely reptilian feature)No really 50/50 in between type. No in between lung structure, no in between femur structure, no in between balance structure, etc.