Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 84 (8914 total)
Current session began: 
Page Loaded: 06-18-2019 10:52 PM
25 online now:
AZPaul3, DrJones*, dwise1, ringo, Tanypteryx, Theodoric (6 members, 19 visitors)
Chatting now:  Chat room empty
Newest Member: 4petdinos
Post Volume:
Total: 854,106 Year: 9,142/19,786 Month: 1,564/2,119 Week: 324/576 Day: 127/98 Hour: 5/6


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Prev12
3
Author Topic:   Theropods and Birds showing a change in kinds
slevesque
Member (Idle past 2805 days)
Posts: 1456
Joined: 05-14-2009


Message 96 of 150 (545641)
02-04-2010 4:06 PM
Reply to: Message 86 by ZenMonkey
02-04-2010 12:03 PM


Re: Wait a sec.
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.

Lol, ok. I guess I'll let you discuss all of this with one another then.


This message is a reply to:
 Message 86 by ZenMonkey, posted 02-04-2010 12:03 PM ZenMonkey has not yet responded

  
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.


This message is a reply to:
 Message 97 by Taq, posted 02-04-2010 4:07 PM Taq has responded

Replies to this message:
 Message 115 by New Cat's Eye, posted 02-05-2010 4:08 PM slevesque has not yet responded
 Message 142 by Taq, posted 02-09-2010 12:23 PM slevesque has not yet responded

  
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:
 Message 100 by Dr Adequate, posted 02-04-2010 9:09 PM Dr Adequate has responded

Replies to this message:
 Message 128 by Dr Adequate, posted 02-05-2010 7:38 PM slevesque has not yet responded

  
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.


This message is a reply to:
 Message 101 by Dr Adequate, posted 02-04-2010 9:18 PM Dr Adequate has responded

Replies to this message:
 Message 120 by ZenMonkey, posted 02-05-2010 4:46 PM slevesque has responded
 Message 134 by Dr Adequate, posted 02-06-2010 4:05 AM slevesque has not yet responded

  
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.


This message is a reply to:
 Message 102 by Dr Adequate, posted 02-04-2010 9:43 PM Dr Adequate has responded

Replies to this message:
 Message 118 by New Cat's Eye, posted 02-05-2010 4:38 PM slevesque has responded
 Message 126 by DC85, posted 02-05-2010 7:23 PM slevesque has not yet responded
 Message 131 by Dr Adequate, posted 02-05-2010 8:56 PM slevesque has not yet responded
 Message 133 by Dr Adequate, posted 02-05-2010 9:56 PM slevesque has not yet responded

  
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.


This message is a reply to:
 Message 103 by Dr Adequate, posted 02-04-2010 11:47 PM Dr Adequate has not yet responded

Replies to this message:
 Message 125 by RAZD, posted 02-05-2010 6:47 PM slevesque has not yet responded

  
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.


This message is a reply to:
 Message 104 by pandion, posted 02-05-2010 12:37 AM pandion has not yet responded

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


Message 121 of 150 (545836)
02-05-2010 4:47 PM
Reply to: Message 118 by New Cat's Eye
02-05-2010 4:38 PM


You really gotta give us links to this stuff

Sorry my bad, I have a lot of catching up to do so I forgot this.

[/qs]The earliest stages in the derivation of the avian abdominal airsac system from a diaphragmatic-ventilating ancestor would have necessitated selection for a diaphragmatic hernia [i.e. hole] in taxa transitional between theropods and birds.

Such a debilitating condition would have immediately compromised the entire pulmonary ventilatory apparatus and seems unlikely to have been of any selective advantage.[/qs]

http://cas.bellarmine.edu/...structure_and_ventilation_i.htm


This message is a reply to:
 Message 118 by New Cat's Eye, posted 02-05-2010 4:38 PM New Cat's Eye has not yet responded

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


Message 122 of 150 (545837)
02-05-2010 4:54 PM
Reply to: Message 120 by ZenMonkey
02-05-2010 4:46 PM


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 should have better expressed myself. What I mean is that if the fakes are well made enough to fool the paleontologists who examine it into thinking they are real and go up to the publishing. How are we going to know about it ? After the research is done, the fossil is simply sent back to china and stored. How much time before anyone else decides to take a look at it again ?

We got lucky with archaeoraptor since Xu Xing happened to see a part of it's original species in a private collection.

The only solution is that the publishers require CT scans on every fossil coming from china before publishing it.

and the quote comes from here:

http://discovermagazine.com/2003/feb/breakdialogue


This message is a reply to:
 Message 120 by ZenMonkey, posted 02-05-2010 4:46 PM ZenMonkey has not yet responded

Replies to this message:
 Message 127 by Dr Adequate, posted 02-05-2010 7:29 PM slevesque has not yet responded
 Message 143 by Taq, posted 02-09-2010 12:32 PM slevesque has not yet responded

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


Message 123 of 150 (545841)
02-05-2010 5:11 PM
Reply to: Message 106 by caffeine
02-05-2010 9:49 AM


Re: Feathers as novel features
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.

The point is that at one point along the lineage the dinosaurs had only down feathers. Assuming that they evolved in a low-humidity environment is cool, but there isn't a lot of those isn't it. Care to give an example of such an environment ? Because it sounds to me the only place this would fit would be the desert.

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?).

I can't access the link, but it's important not to mix up down feathers and 'dinofuzz'.

here 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.

Isn't beta-keratin a pretty common thing ? (My bio classes are far right now lol)

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

I learn new words everyday Some that I even don't know the french translation

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.

Agreed. I wrote an email to Dr. Ruben to inquire about this (Dunno if I have any chance of an answer though)

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.

Yeah misread the article.


This message is a reply to:
 Message 106 by caffeine, posted 02-05-2010 9:49 AM caffeine has responded

Replies to this message:
 Message 140 by caffeine, posted 02-08-2010 5:20 AM slevesque has not yet responded

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


Message 124 of 150 (545842)
02-05-2010 5:12 PM
Reply to: Message 108 by lyx2no
02-05-2010 10:14 AM


Re: Feathers as novel features
Won't stop bullets either. Pure crap, down.

Yeah, I know, bullets are far more common than water in nature ...


This message is a reply to:
 Message 108 by lyx2no, posted 02-05-2010 10:14 AM lyx2no has acknowledged this reply

  
Prev12
3
Newer Topic | Older Topic
Jump to:


Copyright 2001-2018 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2019