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Author Topic:   Theropods and Birds showing a change in kinds
DC85
Member (Idle past 379 days)
Posts: 876
From: Richmond, Virginia USA
Joined: 05-06-2003


Message 76 of 150 (545536)
02-04-2010 6:26 AM
Reply to: Message 72 by slevesque
02-03-2010 5:16 PM


quote:
There exists no half dinosaur/half bird fossils
Of course not they would be separate species in a chain of evolution
quote:
I have already mentioned that birds appear before their supposed ancestors in the fossil record,
This isn't true. They did find an animal that dates to the late Triassic period and theropods existed in the early Triassic. So I do have an issue with the statement. Protoavis is also considered to be a coelurosaurian and not a bird. Which means it was a Triassic theropod .
Edited by DC85, : No reason given.

This message is a reply to:
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Replies to this message:
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caffeine
Member (Idle past 1024 days)
Posts: 1800
From: Prague, Czech Republic
Joined: 10-22-2008


Message 77 of 150 (545542)
02-04-2010 7:19 AM
Reply to: Message 67 by slevesque
02-03-2010 3:10 PM


Re: Feathers as novel features
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)
Not all feathers are optimised for flight, though. There are a plethora of different types of feather - different species have different feathers, and the same species have different feathers on different parts of their body and at different stages in their life. Only a minority of these are the asymmetrical, pennaceous feathers perfectly suited for flight. Most birds begin life covered with fluffed-up downy feathers which aren't at all aerodynamic, but trap air quite well to insulate the little baby bird.
All the functions which people suggest as the ancestral functions of feathers - display, insulation, water resistance etc., are all performed by feathers in modern birds. What's more, if we're thinking evolutionarily, the ancestors of feathers must have been simpler than their current forms - it's silly to suggest the incredibly complex feathers in the tail of a falcon could have sprung up out of nothing. You can simplify the design of a feather considerably, right down to the basic sort of filaments we're looking at in dinosaurs like Sinosauropteryx, and still be left with something that might work as an imperfect insulator, or that could be used for sexual displays. What you're not left with is much of a flight feather.
[qs]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):[qs] Okay, I found the same quote in this article. He doesn't, however, back up the claim anywhere I can find, and despite all my rummaging on the internet, nowhere can I find mention anywhere of a Triassic bird fossil. This includes all the articles I looked at by and about the OSU researchers - were there really such support for this claim, I think they might have mentioned it.
It's possible that he means birds appear in the fossil record before maniraptoran theropods, which are the specific clade of theropods birds are supposed to have evolved from. These are the dinosaurs in which we find true, indisputable feathers; and some of which may have been able to fly (artist's impression from wikipedia below just because I like it).
Let's be clear what's being said here though. Most biologist believe birds to be maniraptoran, coelurosaurian theropods. The earliest fossil theropods predate birds in the fossil record by at least 60 million years. The earliest known coelurosaurian theropod, Eshanosaurus, dates from about 196 million years ago - almost 50 million years before Archaeopteryx. Some dispute that this is really a coelurosaur, and the earliest unquestioned examples come from about the same time or just a bit before Archaeopteryx. Thing is, by this time they're already quite diverse, so they must have already been around for a while.
Even if we discount all the possible but dubious coelurosaurian and maniraptoran fossils that predate Archaeopteryx, we have a huge variety appearing alongside the birds in the late Jurassic and early Cretaceous. If we reject their common theropod ancestor, then we're forced to argue instead that a structure as complex as the feather evolved not just once, but twice, in basically the same form, at about the same time. This stretches credulity a bit.
To RAZD: I'll get back to you, still working on understanding feather follicles.

This message is a reply to:
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Replies to this message:
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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 78 of 150 (545547)
02-04-2010 7:44 AM
Reply to: Message 67 by slevesque
02-03-2010 3:10 PM


Re: Feathers as novel features
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.
Here's one to start you off:
Creationists are going to distort whatever arguments come up, and they've put me in company with luminaries like Stephen Jay Gould, so it doesn't bother me a bit. Archaeopteryx is half reptile and half bird any way you cut the deck, and so it is a Rosetta stone for evolution, whether it is related to dinosaurs or not. These creationists are confusing an argument about minor details of evolution with the indisputable fact of evolution.

This message is a reply to:
 Message 67 by slevesque, posted 02-03-2010 3:10 PM slevesque has replied

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 79 of 150 (545553)
02-04-2010 8:15 AM
Reply to: Message 72 by slevesque
02-03-2010 5:16 PM


There exists no half dinosaur/half bird fossils.
What, in your opinion, is Archaeopteryx, then? Chopped liver?
And I have already mentioned that birds appear before their supposed ancestors in the fossil record ...
If you think about that statement for a moment, you will see that it can't possibly be true. Biologists, you see, know quite a lot about biology, and this means that none of them supposes that birds lived before their ancestors.
Add to that the fact that there are a lot of fake dinosaur-bird fossils out there coming from china ...
Which paleontologists can spot, which is the only reason you know that in the first place.

This message is a reply to:
 Message 72 by slevesque, posted 02-03-2010 5:16 PM slevesque has replied

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Huntard
Member (Idle past 2295 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 80 of 150 (545555)
02-04-2010 8:56 AM
Reply to: Message 79 by Dr Adequate
02-04-2010 8:15 AM


Dr Adequate writes:
If you think about that statement for a moment, you will see that it can't possibly be true. Biologists, you see, know quite a lot about biology, and this means that none of them supposes that birds lived before their ancestors.
To be fair to Slevesque, he did say supposed ancestors. With which I think he is referring to Archaeopteryx. Therefore he is not saying they lived before their "actual" ancestors (Whatever they may be to him), but that the ancestors that are currently classified as such are not the ancestors.
Edited by Huntard, : tiepo

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 Message 79 by Dr Adequate, posted 02-04-2010 8:15 AM Dr Adequate has replied

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 81 of 150 (545557)
02-04-2010 9:11 AM
Reply to: Message 80 by Huntard
02-04-2010 8:56 AM


To be fair to Slevesque, he did say supposed ancestors.
And to be fair to biologists, they suppose no such thing.
Edited by Dr Adequate, : No reason given.

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 Message 80 by Huntard, posted 02-04-2010 8:56 AM Huntard has replied

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Huntard
Member (Idle past 2295 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 82 of 150 (545558)
02-04-2010 9:19 AM
Reply to: Message 81 by Dr Adequate
02-04-2010 9:11 AM


Dr Adequate writes:
And to be fair to biologists, they suppose no such thing.
Biologists haven't classified anything as the ancestor to modern birds?

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 Message 81 by Dr Adequate, posted 02-04-2010 9:11 AM Dr Adequate has not replied

  
Taq
Member
Posts: 9972
Joined: 03-06-2009
Member Rating: 5.6


Message 83 of 150 (545566)
02-04-2010 10:34 AM
Reply to: Message 72 by slevesque
02-03-2010 5:16 PM


There exists no half dinosaur/half bird fossils.
So we have gone from "fingerprints are not compelling evidence" to "what fingerprints?".
Is that how a court of law works? Proof beyond a reasonable doubt once you have ignored the evidence?
The fact of the matter is that there are fossils with dinosaur characteristics not found in any living bird. These same fossils have avian features not found in other dinosaurs. How is this not half dino/half bird?
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.
No one has named the ancestral species of all birds.
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.
In a court of law can the defending attorney cite a single incident of evidence tampering in a separate case to throw out all evidence?
"Your honor, someone planted John Smith's fingerprints at the scene of the crime in 1945, so surely the fingerprint evidence against my client in 2010 should be dropped."
Is that reasonable?
Edited by Taq, : No reason given.

This message is a reply to:
 Message 72 by slevesque, posted 02-03-2010 5:16 PM slevesque has replied

Replies to this message:
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New Cat's Eye
Inactive Member


Message 84 of 150 (545574)
02-04-2010 11:00 AM
Reply to: Message 67 by slevesque
02-03-2010 3:10 PM


Re: Feathers as novel features
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)
They put down feathers in coats because they ARE great for thermoregulation.
And do you have any links for this supposed bird that was found to be before the proposed ancestor(s)?
Edited by Catholic Scientist, : No reason given.

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Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 85 of 150 (545578)
02-04-2010 11:28 AM


Hi, Everyone.
When Slevesque talked about "appearing before supposed ancestors," I think he's talking about the temporal paradox argument: Archaeopteryx occurs earlier in the fossil record than the groups of dinosaurs from which it is supposed to have evolved.
It's a Feduccia argument, and one for which there is apparently an evidenced rebuttal: fragmentary remains of maniraptoran dinosaurs are found earlier than Archaeopteryx, even though they are sparse and a bit non-diagnostic.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

  
ZenMonkey
Member (Idle past 4510 days)
Posts: 428
From: Portland, OR USA
Joined: 09-25-2009


Message 86 of 150 (545582)
02-04-2010 12:03 PM
Reply to: Message 74 by slevesque
02-03-2010 11:50 PM


Re: Wait a sec.
slevesque writes:
ZenMonkey writes:
slevesque, why are you bothering with fossils anyway, since you - if you are indeed a YEC - believe that the world's age is measured only in thousands of years, not millions or billions?
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.
No, I'm sorry, but if you don't accept the dating of fossil evidence, that invalidates any argument that you want to put forth regarding the order and relationship of that same evidence.
You can't have it both ways. I'm not asking you to justify your rejection of radiometric and other dating methods. However, if you really believe that all the fossil evidence is recent and roughly contemporaneous, then you have no basis whatsoever to claim that any particular fossil predates another.
Pick one or the other.

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slevesque
Member (Idle past 4640 days)
Posts: 1456
Joined: 05-14-2009


Message 87 of 150 (545628)
02-04-2010 3:16 PM
Reply to: Message 75 by DC85
02-04-2010 6:11 AM


do you find the complexity of life as proof of a creator? I know this is off topic however I find important to ask as such and assumption is a far larger stretch.
I think it is evidence of a creator, but not proof.
what would be compelling evidence? DNA isn't compelling to you. Transitional fossils aren't. ... What do we need to show you?
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)
there is one and we have how many between humans and chimps?
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)

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slevesque
Member (Idle past 4640 days)
Posts: 1456
Joined: 05-14-2009


Message 88 of 150 (545629)
02-04-2010 3:19 PM
Reply to: Message 76 by DC85
02-04-2010 6:26 AM


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.

This message is a reply to:
 Message 76 by DC85, posted 02-04-2010 6:26 AM DC85 has replied

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PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 89 of 150 (545630)
02-04-2010 3:22 PM
Reply to: Message 87 by slevesque
02-04-2010 3:16 PM


quote:
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.
Punctuated Equilibria is not ad hoc. It was derived from accepted evolutionary theory (Mayr's theory of allopatric speciation). And it is far from clear that the fossil record only shows PE, as you claim.

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slevesque
Member (Idle past 4640 days)
Posts: 1456
Joined: 05-14-2009


Message 90 of 150 (545634)
02-04-2010 3:40 PM
Reply to: Message 77 by caffeine
02-04-2010 7:19 AM


Re: Feathers as novel features
Hi caffeine,
Not all feathers are optimised for flight, though. There are a plethora of different types of feather - different species have different feathers, and the same species have different feathers on different parts of their body and at different stages in their life. Only a minority of these are the asymmetrical, pennaceous feathers perfectly suited for flight. Most birds begin life covered with fluffed-up downy feathers which aren't at all aerodynamic, but trap air quite well to insulate the little baby bird.
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.
Okay, I found the same quote in this article. He doesn't, however, back up the claim anywhere I can find, and despite all my rummaging on the internet, nowhere can I find mention anywhere of a Triassic bird fossil. This includes all the articles I looked at by and about the OSU researchers - were there really such support for this claim, I think they might have mentioned it.
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
Even if we discount all the possible but dubious coelurosaurian and maniraptoran fossils that predate Archaeopteryx, we have a huge variety appearing alongside the birds in the late Jurassic and early Cretaceous. If we reject their common theropod ancestor, then we're forced to argue instead that a structure as complex as the feather evolved not just once, but twice, in basically the same form, at about the same time. This stretches credulity a bit.
Convergent evolution can do marvels. Exactly the same sonar structure up down to the genome level in dolphins and bats, for example.

This message is a reply to:
 Message 77 by caffeine, posted 02-04-2010 7:19 AM caffeine has replied

Replies to this message:
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 Message 103 by Dr Adequate, posted 02-04-2010 11:47 PM slevesque has replied
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 Message 108 by lyx2no, posted 02-05-2010 10:14 AM slevesque has replied

  
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