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Author Topic:   Theropods and Birds showing a change in kinds
caffeine
Member
Posts: 1670
From: Prague, Czech Republic
Joined: 10-22-2008
Member Rating: 5.2


Message 106 of 150 (545780)
02-05-2010 9:49 AM
Reply to: Message 90 by slevesque
02-04-2010 3:40 PM


Re: Feathers as novel features
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.

Assuming that this is the case, it might imply merely that plumulaceous, downy feathers were evolved for thermoregulation in a low-humidity environment when getting wet was rarely a problem. Also, simple observation seems to suggest that feathers can't be that poor at insulation. Despite maintaining higher inner temperatures than mammals, even small birds seem to have little problem surviving at the highest latitudes. Snow petrels happily breed right at the sorth pole, and they're less than half a metre long.

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.

Many dinosaurs have been found with downy feathers all oviraptoriformes seem to have possessed at least some, and theres a new taxon reported in Nature last year which not only seems to have possessed downy feathers, but also appears to be a maniraptoran theropod from before Archaeopteryx. (Incidentally, does anyone have access to Nature so that we can confirm this article says what I think it says?).

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.

There is indeed something to link these structures to feathers. Unlike other epidermal coverings, feathers are composed almost entirely of beta-keratins. When the 'dinofuzz' filaments of the theropod Shuvuuia were examined to determine their makeup, it was discovered that, they too, are composed almost entirely of beta-keratins (Schweitzer, M. H. 2001. Evolutionary implications of possible protofeather structures associated with a specimen of Shuvuuia deserti. In Gauthier, J. & Gall, L. F. (eds) New prespectives on the origin and early evolution of birds: proceedings of the international symposium in honor of John H. Ostrom. Peabody Museum of Natural History, Yale University (New Haven), pp. 181-192. - found on Tetrapod Zoology ). One more coincidence if these are believed to be non-homologous structures.

If it turns out that the possible filaments found in ornithischian dinosaurs and pterosaurs are, in fact, the same things as found in theropods, this might simply suggest that beta-keratin filaments are a primitive ornithodiran* trait, originally evolved for insulation and/or display. In this model, it would be the later specialisation of these structures into true feathers in theropod dinosaurs that paved the way for the great evolutionary radiation of birds.

*My new word for the day. Ornithodira is the clade that unites dinosaurs and pterosaurs.

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

Okay to clarify though, everybody agrees that theropods appear in the fossil record long before birds. Whats a matter for dispute still is whether the specific type of theropod birds are believed to have evolved from appear before them.

Convergent evolution can do marvels. Exactly the same sonar structure up down to the genome level in dolphins and bats, for example.

As pointed out upthread - this isn't really true. Bats and dolphins have quite distinct sonar structures. All that's been discovered is that one gene involved in sonar seems to possess the same mutations in the two different animals.

Edited by caffeine, : No reason given.


This message is a reply to:
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caffeine
Member
Posts: 1670
From: Prague, Czech Republic
Joined: 10-22-2008
Member Rating: 5.2


Message 107 of 150 (545782)
02-05-2010 9:56 AM
Reply to: Message 102 by Dr Adequate
02-04-2010 9:43 PM


Phylogenetic nitpick
A coelurosaur such as Compsognathus is much closer anatomically to Archaeopteryx than it is to another theropod dinosaur --- T. rex, for example. And Archaeopteryx is much closer anatomically to Compsognathus than it is to, for example, a sparrow (or any other living bird, for that matter).

Tyrannosaurs are coelurosaurs, just slightly more distantly related to birds than compsognathids. A better example would be comparing archaeopteryx to paravian dinosaurs like Velociraptor or Dromaeosaurus; compared with a more distant theropod like Allosaurus.


This message is a reply to:
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lyx2no
Member (Idle past 2881 days)
Posts: 1277
From: A vast, undifferentiated plane.
Joined: 02-28-2008


Message 108 of 150 (545786)
02-05-2010 10:14 AM
Reply to: Message 90 by slevesque
02-04-2010 3:40 PM


Re: Feathers as novel features
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.

Won't stop bullets either. Pure crap, down.


You are now a million miles away from where you were in space-time when you started reading this sentence.
This message is a reply to:
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Dr Adequate
Member
Posts: 16096
Joined: 07-20-2006


Message 109 of 150 (545797)
02-05-2010 12:21 PM
Reply to: Message 107 by caffeine
02-05-2010 9:56 AM


Re: Phylogenetic nitpick
Tyrannosaurs are coelurosaurs, just slightly more distantly related to birds than compsognathids.

True ... and yet doesn't that make my point even pointier? Which really looks like the odd one out --- Tyrannosaurus, Compsognathus, Archaeopteryx? I have to go with Tyrannosaurus.

So I guess what I should have said is: "A maniraptor such as Compsognathus is much closer anatomically to Archaeopteryx than it is to another coelurosaur --- T. rex, for example."


This message is a reply to:
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Dr Adequate
Member
Posts: 16096
Joined: 07-20-2006


Message 110 of 150 (545799)
02-05-2010 12:58 PM
Reply to: Message 106 by caffeine
02-05-2010 9:49 AM


Anchiornis
Many dinosaurs have been found with downy feathers all oviraptoriformes seem to have possessed at least some, and theres a new taxon reported in Nature last year which not only seems to have possessed downy feathers, but also appears to be a maniraptoran theropod from before Archaeopteryx.

Your link isn't working for me --- are we thinking of the same article? "A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus"?

Yes, Anchiornis is a pre-Archaeopteryx maniraptor. So either the creationists will have to abandon an argument merely because it's been proved totally wrong --- or, and this is what I'm guessing, they'll decide to classify a non-avialan dinosaur as being a bird with nothing dinosaurian about it at all. Or perhaps they'll impute that it's a fake without offering a scrap of evidence for this. Or they'll attack the dating methods in which they seemingly put implicit trust before the temporal paradox was resolved by the application of those exact same methods to the new fossils. Or ...


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New Cat's Eye
Inactive Member


Message 111 of 150 (545804)
02-05-2010 1:28 PM
Reply to: Message 110 by Dr Adequate
02-05-2010 12:58 PM


Re: Anchiornis
Your link isn't working for me

He put a space after the '=' in the url coding and that puts a %20 in the address line...

Here's the paper:

http://www.nature.com/...rnal/v461/n7264/pdf/nature08322.pdf


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slevesque
Member (Idle past 2805 days)
Posts: 1456
Joined: 05-14-2009


Message 112 of 150 (545822)
02-05-2010 3:58 PM
Reply to: Message 97 by Taq
02-04-2010 4:07 PM


Modern birds are classified as dinosaurs and are complete dinosaurs, so I really don't see your point. The fact of the matter is that fossils like Archaeopteryx have a mixture of non-avian dinosaur features and modern bird features. Can you please tell us why this is not a transitional fossil? What criteria are you using to determine if a fossil is transitional or not?

Equivocating the word bird to dinosaur won't really help anything in the discussion. If birds are just dinosaur, how can anything be transitional between dinosaurs and birds ?

Obviously, there are features that distinguish birds from their dinosaur ancestors. These are the ones that have to be shown transitional.


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slevesque
Member (Idle past 2805 days)
Posts: 1456
Joined: 05-14-2009


Message 113 of 150 (545823)
02-05-2010 4:00 PM
Reply to: Message 100 by Dr Adequate
02-04-2010 9:09 PM


Re: Feathers as novel features
I think what hurt his reputation was being wrong. How much attention do you think the average biologist pays to creationists?

In what way do you think he contradicts himself?

Because he argues elsewhere that archaeoptryx was a perching bird. (which is the correct anatomical conclusion) which is in a contradiction of his half bird/half dinosaur quote you posted earlier.


This message is a reply to:
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slevesque
Member (Idle past 2805 days)
Posts: 1456
Joined: 05-14-2009


Message 114 of 150 (545824)
02-05-2010 4:05 PM
Reply to: Message 101 by Dr Adequate
02-04-2010 9:18 PM


Can you name any other fake primitive bird from China that managed to temporarily fool a couple of paleontologists?

So far as I know, no primitive bird fossil that has got into the scientific literature has subsequently been exposed as a "Piltdown bird". If you know better, let me know.

And if this had happened, you would know about it, would you?

If a fossil had happened to fool a couple of paleontologist, maybe we wouldn't, in fact, have heard about it.

Because creationists, who would have played absolutely no role in uncovering the hoax, and not one of whom could tell a real fossil from a fake fossil from a hole in the bleedin' ground, would never shut up about how this proves that all biologists are stupid and EVIL-UTION IS A LIE OMG!!!

Totally unecessary.


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


Message 115 of 150 (545825)
02-05-2010 4:08 PM
Reply to: Message 112 by slevesque
02-05-2010 3:58 PM


Equivocating the word bird to dinosaur won't really help anything in the discussion. If birds are just dinosaur, how can anything be transitional between dinosaurs and birds ?

That would make them the same kind but then how'd they get so different if they only bring forth after their own kind?

Obviously, there are features that distinguish birds from their dinosaur ancestors.

I think its obvious that they're different kinds too.

These are the ones that have to be shown transitional.

And that they have been shows that one kind has become another, i.e. the point of this thread.


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slevesque
Member (Idle past 2805 days)
Posts: 1456
Joined: 05-14-2009


Message 116 of 150 (545828)
02-05-2010 4:22 PM
Reply to: Message 102 by Dr Adequate
02-04-2010 9:43 PM


Archaeopteryx does not in fact have all the characteristics of modern birds.

---

The problem with this, as with every similar creationist attempt at shoehorning, is that the extremal members of the two groups thus artificially constructed are closer anatomically then they are to other members of "their own" groups.

A coelurosaur such as Compsognathus is much closer anatomically to Archaeopteryx than it is to another theropod dinosaur --- T. rex, for example. And Archaeopteryx is much closer anatomically to Compsognathus than it is to, for example, a sparrow (or any other living bird, for that matter).

Or to put it another way, if Archeopteryx is a bird, and Compsognathus is a dinosaur, then Archaeopteryx is a bird with almost completely dinosaurian features (since it's almost exactly the same as Compsognathus), and Compsognathus is a dinosaur with almost exclusively avian features (since it's almost exactly the same as Archaeopteryx).

Placing the division where you do therefore has nothing to do with anatomy and everything to do with the creationist need to draw a line somewhere. Anywhere.

Maybe because Compsognathus, as archaeopteryx, was a perching bird ?

Perhaps you could elaborate on this.

* Lungs: the evidence shows that dinosaurs had the same sort of lungs as birds. Why should there be something "in between" two structures which are identical?

I don't know where you get this. Alleged feathered dinosaurs such as Sinosauropteryx have bellowslike lungs which are very different from avian lungs. Dr. Ruben is a respiratory physiology expert and he says that there is no evolutionnary path between the two types of lungs. (Because the very first step needed would be harmful)

* Femurs: well, since you've decided that Archaeopteryx is a bird, and that coelurosaurs are not, could you explain to us what the anatomical difference is between the femurs of the two? If there isn't any, then my remarks about lungs apply.

I don't know the lung structure of Coelurosaurs. I know that birds have fixed femurs inside there body because if they didn't there lungs would collapse. I also know that therapods did not.

* Balance structure: I don't know what you mean, please explain. And, again, will you please let us know if Archaeopteryx, which you deem a bird, really has a different "balance structure" from a coelurosaur.

I mean that shortened forelimbs and heavy, balancing tails isn't quite the good anatomy for flight. Birds centre of mass has to be well balanced in order for flying to be possible. This applies to archaeopteryx.

I find little information on the net concerning Coelurosaurs, so you'll have to tell me.


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slevesque
Member (Idle past 2805 days)
Posts: 1456
Joined: 05-14-2009


Message 117 of 150 (545830)
02-05-2010 4:35 PM
Reply to: Message 103 by Dr Adequate
02-04-2010 11:47 PM


Re: Feathers as novel features
So, the omniscient creator really screwed up by giving baby birds down, eh? Either that or he's just trying to kill as many cute little dicky-birds as possible.

That's because he also make them grow real feathers shortly after they are born so that they are protected from the rain.

You do not explain why the same dreadful fate does not befall the adult ostrich when she gets wet. Is there something in particular which makes wet down a poorer insulator than wet feathers? Or why either should be inferior to naked skin?

Real feathers are waterproof. That's why they are better insulators when they are 'wet'.

But you are telling me, that the ancestor of birds had only down feathers for insulation. Which is a very bad adaptation, because well, rain happens.

But see here.

You do know that these are down feathers in amber and are being related to dinosaurs because they found dinosaur teeth in the layer above the amber ? I find that a bit speculative.

And, for some reason which you can't quite explain, the mere existence of therapods with feathers doesn't support a link between therapods and birds.

There is two reasons for this. I haven't really checked in any sort of detail any supposedly feathered therapods you gave as an example.

And

A Complete feather isn't reall an intermediate stage between a feather and a feather. And nothing me from thinking some species of dinosaurs to have feathers.

The value of your example is vitiated by being totally made up.

I misread the article. My bad.


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New Cat's Eye
Inactive Member


Message 118 of 150 (545831)
02-05-2010 4:38 PM
Reply to: Message 116 by slevesque
02-05-2010 4:22 PM


Maybe because Compsognathus, as archaeopteryx, was a perching bird ?

Nah, it doesn't really have "wings"...

Here's the skeleton:

Scientists think it might have been covered with small feathers and could have looked something like this:

Although, there's not enough info yet:

quote:
Some relatives of Compsognathus, namely Sinosauropteryx and Sinocalliopteryx, have been preserved with the remains of simple feathers covering the body like fur,[27] promoting some scientists to suggest that Compsognathus might have been feathered in a similar way.[28] Consequently, many depictions of Compsognathus show it with a covering of downy proto-feathers. However, no feathers or feather-like covering have been preserved with Compsognathus fossils, in contrast to Archaeopteryx, which was found in the same sediments. Karin Peyer, in 2006, reported skin impressions preserved on the side of the tail starting at the 13th tail vertebra. The impressions showed small bumpy tubercles, similar to the scales found on the tail and hind legs of Juravenator.[29] Additional scales had earlier been reported by Von Huene, in the abdominal region of the German Compsognathus, but Ostrom later disproved this interpretation.[24][13]

Like Compsognathus, and unlike Sinosauropteryx, a patch of fossilized skin from the tail and hindlimb of the possible relative Juravenator shows mainly scales, though there is some indication that simple feathers were also present in the preserved areas.[30] This may mean that a feather covering was not ubiquitous in this group of dinosaurs.source


Dr. Ruben is a respiratory physiology expert and he says that there is no evolutionnary path between the two types of lungs.

You really gotta give us links to this stuff


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slevesque
Member (Idle past 2805 days)
Posts: 1456
Joined: 05-14-2009


Message 119 of 150 (545832)
02-05-2010 4:43 PM
Reply to: Message 104 by pandion
02-05-2010 12:37 AM


My bet is that he can't name any fake, primitive bird from anywhere that fooled paleontologists. Archaeoraptor did fool a few amateurs, but the first qualified paleontologists who examined the fossil recognized it as a fake at first glance.

So you think a fossil is published in national geographic without even one qualified paleontologists having a look at it ? You didn't give a lot of thought into this did you ...

The very paleoontolgist who realized it was a fraud, Xu Xing, had been one of the paleotologist who had originally examined archaeoraptor. It was only when she got back at a private collection that she recognized a portion of archaeoraptor into a fossil of a dromaeosaur.

So not, you don't recognize them 'at first glance'.

They proved it with CT scans and concluded that the fossil was composed of 3 to 5 separate fossils.

In many cases, the fakes are so well made that a CT scan or Xray is the only way to see if it is a fake. The problem being that journals such as nature o not require this procedure to take place for a find to be published.

I hate having to post something twice, but I guess I'll have to. Read it all carefully this time:

Discover: What about all the other evidence for feathered dinosaurs?

Feduccia: When we see actual feathers preserved on specimens, we need to carefully determine if we are looking at secondarily flightless birds that have retained feathers and only superficially resemble dinosaurs, or if the specimens are in fact related to dinosaurs. Thats a difficult issue to deal with right now, given the existence of fake fossils.

Discover: So far, only one feathered dinosaur, Archaeoraptor, has been publicly acknowledged as a forgery. You think there are others?

Feduccia: Archaeoraptor is just the tip of the iceberg. There are scores of fake fossils out there, and they have cast a dark shadow over the whole field. When you go to these fossil shows, its difficult to tell which ones are faked and which ones are not. I have heard that there is a fake-fossil factory in northeastern China, in Liaoning Province, near the deposits where many of these recent alleged feathered dinosaurs were found.

Journals like Nature dont require specimens to be authenticated, and the specimens immediately end up back in China, so nobody can examine them. They may be miraculous discoveries, they may be missing links as they are claimed, but there is no way to authenticate any of this stuff.

Discover: Why would anyone fake a fossil?

Feduccia: Money. The Chinese fossil trade has become a big business. These fossil forgeries have been sold on the black market for years now, for huge sums of money. Anyone who can produce a good fake stands to profit.


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ZenMonkey
Member (Idle past 2675 days)
Posts: 428
From: Portland, OR USA
Joined: 09-25-2009


Message 120 of 150 (545835)
02-05-2010 4:46 PM
Reply to: Message 114 by slevesque
02-05-2010 4:05 PM


slevesque writes:

If a fossil had happened to fool a couple of paleontologist, maybe we wouldn't, in fact, have heard about it.

Please substantiate this assertion or withdraw it.

This allegation of professional dishonesty is baseless. (At least I think that misconduct or ignorance is what you're trying to imply.) It also doesn't make sense. Don't creationists commonly accuse paleontologists of promoting false fossil evidence, rather than trying to cover it up to hide their mistakes, or using fakes to support a "failed theory"? I'm not at all certain what you're saying here, other than you're trying to weasel out of your previous unsubtantiated claim in Message 36 that there were "scores of fake fossils" coming out of China. Yeah, I know that your quote came from a supposed interveiw with Feducia, but there doesn't appear to be any basis for him saying this either. I also note that you don't give a link or a citation for your quote. Where did it come from?


I have no time for lies and fantasy, and neither should you. Enjoy or die.
-John Lydon
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