Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 78 (8905 total)
Current session began: 
Page Loaded: 04-24-2019 6:39 PM
36 online now:
Tangle, Tanypteryx (2 members, 34 visitors)
Chatting now:  Chat room empty
Newest Member: WookieeB
Post Volume:
Total: 850,193 Year: 5,230/19,786 Month: 1,352/873 Week: 248/460 Day: 64/29 Hour: 1/1


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Prev1
...
5678
9
10Next
Author Topic:   Theropods and Birds showing a change in kinds
slevesque
Member (Idle past 2750 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 2750 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 2750 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 2750 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

  
RAZD
Member
Posts: 19819
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 10.0


Message 125 of 150 (545857)
02-05-2010 6:47 PM
Reply to: Message 117 by slevesque
02-05-2010 4:35 PM


Re: Feathers as novel features
Hi slevesque, sorry to add to your burden here

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

The anhinga can barely fly when it emerges from the water due to the amount of water absorbed by its feathers. It has to sit in the sun to dry out, resulting in a recognizable pose.

http://en.wikipedia.org/wiki/Anhinga

quote:
Unlike ducks, the Anhinga is not able to waterproof its feathers using oil produced by the uropygial gland. Consequently, feathers can become waterlogged, making the bird barely buoyant. However, this allows it to dive easily and search for underwater prey, such as fish and amphibians. It can stay down for significant periods.

When necessary, the Anhinga will dry out its wings and feathers. It will perch for long periods with its wings spread to allow the drying process, as do cormorants. If it attempts to fly while its wings are wet, it has great difficulty getting off the water and takes off by flapping vigorously while 'running' on the water. Anhinga will often search for food in small groups.

Birds that don't oil their feathers (like sparrows etc) can drown in water.

Enjoy

Edited by RAZD, : enjoy


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 117 by slevesque, posted 02-05-2010 4:35 PM slevesque has not yet responded

  
DC85
Member (Idle past 442 days)
Posts: 875
From: Richmond, Virginia USA
Joined: 05-06-2003


Message 126 of 150 (545860)
02-05-2010 7:23 PM
Reply to: Message 116 by slevesque
02-05-2010 4:22 PM


I do believe before we continue we should understand the time periods we're talking about.

I do believe you need to brush up on the following

Permian
Triassic
Jurassic
Cretaceous

These are very important to this discussion before you keep spouting about proto feathers and the lack of insulation. please try to understand. the climates of the time periods and that these animals most likely didn't go jumping into lakes. Notice how hair has some of the same problems? I wonder why cats have fur and why whales and seals have far shorter and less of it.

I'd also like to submit yet another transitional animal. Please tell me if the following is a Mammal or if it is a reptile. This Animal lived during the late permian and early Triassic

Edited by DC85, : No reason given.

Edited by DC85, : spelling error


This message is a reply to:
 Message 116 by slevesque, posted 02-05-2010 4:22 PM slevesque has not yet responded

Replies to this message:
 Message 129 by ZenMonkey, posted 02-05-2010 8:42 PM DC85 has responded

    
Dr Adequate
Member
Posts: 16094
Joined: 07-20-2006
Member Rating: 9.0


Message 127 of 150 (545861)
02-05-2010 7:29 PM
Reply to: Message 122 by slevesque
02-05-2010 4:54 PM


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.

In the first place, that isn't the only reason. Another reason is that Tim Rowe did in fact do a CT scan and find problems with the fossil.

And the scientific journals did in fact refuse to publish the papers they were sent.

What we have here is an example of how science works, how the peer-review system works, how amateurs should defer to the professionals, and how paleontologists know what they're doing.

Edited by Dr Adequate, : No reason given.


This message is a reply to:
 Message 122 by slevesque, posted 02-05-2010 4:54 PM slevesque has not yet responded

  
Dr Adequate
Member
Posts: 16094
Joined: 07-20-2006
Member Rating: 9.0


Message 128 of 150 (545863)
02-05-2010 7:38 PM
Reply to: Message 113 by slevesque
02-05-2010 4:00 PM


Re: Feathers as novel features
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.

I think you're splitting hairs. It was a perching bird, by definition of the clade of birds (and perching because I believe the consensus view is now that it had a reversed hallux). It is also an intermediate between dinosaurs and modern birds.


This message is a reply to:
 Message 113 by slevesque, posted 02-05-2010 4:00 PM slevesque has not yet responded

  
ZenMonkey
Member (Idle past 2620 days)
Posts: 428
From: Portland, OR USA
Joined: 09-25-2009


Message 129 of 150 (545873)
02-05-2010 8:42 PM
Reply to: Message 126 by DC85
02-05-2010 7:23 PM


Again with the dating.
DC85 writes:

I do believe before we continue we should understand the time periods we're talking about.

I still assert that, as a YEC, slevesque has no standing to assert anything whatsoever regarding the dating and relationships of fossil evidence. To continue to attempt to support his arguments by using evidence he does not in all honesty consider valid is arguing in bad faith.

I'm not trying to be a dick, but is it too much to ask someone to refrain from using evidence he or she does not really believe to be true?


I have no time for lies and fantasy, and neither should you. Enjoy or die.
-John Lydon
This message is a reply to:
 Message 126 by DC85, posted 02-05-2010 7:23 PM DC85 has responded

Replies to this message:
 Message 130 by RAZD, posted 02-05-2010 8:52 PM ZenMonkey has not yet responded
 Message 132 by DC85, posted 02-05-2010 9:45 PM ZenMonkey has not yet responded

  
RAZD
Member
Posts: 19819
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 10.0


Message 130 of 150 (545874)
02-05-2010 8:52 PM
Reply to: Message 129 by ZenMonkey
02-05-2010 8:42 PM


Re: Again with the dating.
Hi ZenMonkey,

I still assert that, as a YEC, slevesque has no standing to assert anything whatsoever regarding the dating and relationships of fossil evidence.

Perhaps he is trying to understand the evolutionist argument thoroughly first.

See Honest Debate: how do you read?

Enjoy.


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 129 by ZenMonkey, posted 02-05-2010 8:42 PM ZenMonkey has not yet responded

  
Dr Adequate
Member
Posts: 16094
Joined: 07-20-2006
Member Rating: 9.0


Message 131 of 150 (545877)
02-05-2010 8:56 PM
Reply to: Message 116 by slevesque
02-05-2010 4:22 PM


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

So you're now going to draw the line between birds and dinosaurs so that this is included with the birds?

But don't you see, this leaves you with exactly the same problem. Compsognathus is more like some animals on the dinosaur side of the line than it is to other members of the bird group you'd like to lump it in with. Heck, it's even more similar to some non-dinosaur archosaurs than it is to a modern bird.

Here's Lagosuchus. This saurian isn't even classed as a dinosaur.

And this, slevesque, is a chicken.

Everyone join in the song ...

If Compsognathus and other maniraptors are birds, but the other coelurosaurs are not, then the maniraptors are birds with almost completely coelurosaur features, and the other coelurosaurs are dinosaurs with almost entirely avian features.. You want to throw in the coelusrosaurs as birds, but say that the other therapods are not? Very well then, the coelurosaurs are birds with almost entirely therapod features, whereas the therapods are dinosaurs with almost completely avian features ... and this is going to happen wherever you draw the line. Are you going to keep going until you've decided that all therapods are birds? That all dinosaurs are birds? And then I'm going to make you start throwing non-dinosaur archosaurs in as well. Are you going to drag the crocodiles into this too? Where would you like to stop?

I don't know where you get this. Alleged feathered dinosaurs such as Sinosauropteryx have bellowslike lungs which are very different from avian lungs.

Hold on, hold on. Stop right there. Wait just one darned cotton-picking minute. According to your link to Ruben et al, which you kindly provide in a subsequent post, Archaeopteryx and other primitive birds had just the same sort of lungs as dinosaurs. And Archaeopteryx, you say, is a bird. So we don't need to find a transition between the lungs of dinosaurs and birds, because the most primitive birds had the same sort of lungs as dinosaurs.

I may have more to say about lungs later, I'll have to look some stuff up.

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.

I know the paper you're basing this on. I also know what else, according to that same paper, didn't have fixed femurs. Can you guess what?

That's right. Archaeopteryx.

Let me quote from the paper (Quick and Ruben, 2009):

Many of these skeletal specializations are not apparent in the earliest birds, including Archaeopteryx, confuciusornithine or enantiornithine birds (Hillenius and Ruben, 2004a). Their presence is also questionable in even Early Cretaceous ornithurines but well developed in the Late Cretaceous hesperornithiform birds (Hillenius and Ruben, 2004a). The femur most likely did not attain its subhorizontal position until the Late Cretaceous in ornithurines as indicated by the presence of the antitrochanter...

And what's Archaeopteryx? It's a bird. You said.

So we don't need to find a transition between dinosaur femurs and bird femurs because the most primitive birds have the same sort of femurs as dinosaurs.

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.

And let's do this one more time. Archaeopteryx has a long bony tail. Like a dinosaur. And what did you say Archaeopteryx was, remind me? Oh yes, it's a bird.

So we don't need to find a transition between the tails of dinosaurs and the tails of birds, because the most primitive birds have just the same sorts of tails as dinosaurs.

You might, perhaps, ask for transitions in the tail between primitive and modern birds, and unless my memory has gone completely haywire, there are plenty.

Are you sure you wouldn't now like to classify Archaeopteryx as a dinosaur?

Well, that's why they call them intermediate forms.

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

I'll come back to that in a subsequent post ... this one, I feel, is quite long enough.


This message is a reply to:
 Message 116 by slevesque, posted 02-05-2010 4:22 PM slevesque has not yet responded

  
DC85
Member (Idle past 442 days)
Posts: 875
From: Richmond, Virginia USA
Joined: 05-06-2003


Message 132 of 150 (545882)
02-05-2010 9:45 PM
Reply to: Message 129 by ZenMonkey
02-05-2010 8:42 PM


Re: Again with the dating.
I still assert that, as a YEC, slevesque has no standing to assert anything whatsoever regarding the dating and relationships of fossil evidence. To continue to attempt to support his arguments by using evidence he does not in all honesty consider valid is arguing in bad faith.
So even though climates and earth formations are an important part of evolution I shouldn't use the enivonment the animal lived in to to explain? my point was the Jurrassic period was very different then it is today
This message is a reply to:
 Message 129 by ZenMonkey, posted 02-05-2010 8:42 PM ZenMonkey has not yet responded

    
Dr Adequate
Member
Posts: 16094
Joined: 07-20-2006
Member Rating: 9.0


Message 133 of 150 (545883)
02-05-2010 9:56 PM
Reply to: Message 116 by slevesque
02-05-2010 4:22 PM


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

Specifically, let us consider the compsognathidae, Archaeopteryx, and modern birds.

Now, in the following series, which I prepared for an article I wrote, I have not always been able to use the same compsignathid and the same modern bird, because I had to go with what I could find. On my word of honor, however, I have not in any way cherry-picked the compsognathids and the modern birds to make my point.

In all these pictures, the order, either from top to bottom or from left to right, is: compsognathid, Archaeopteryx, modern bird.

Let's start with the skulls, shall we?

Now some pelves:

You should also note that in modern birds the pelvis is fused to the adjacent vertebrae, a fact which is not shown on this diagram.

Now the manus. Note that these have been rescaled to be the same length. I didn't do that, it's how I got 'em. You'll be able to see the true proportions in the next picture on.

And now let's take an overview of the entire skeletal anatomy:

Some point of interest:

* The tail. In the modern bird, this has been reduced to a pygostyle.

* The large keeled breastbone of the modern bird.

* The synsacrum --- that's the plate of bone on the back and to the rear of the modern bird, formed by fusion of ribs.

* The gastralia or so-called "abdominal ribs" --- the fine structures along the belly of the dinosaur (Compsognathus) and Archaeopteryx.

* The femurs. In the modern bird, as mentioned in my previous post, these are fixed in a near-horizontal position.

Now, we could go on to discuss the finer details, or we could just sing along with the Cookie Monster:

So, do you want to declare Compsognathus a bird, or do you want to declare Archaeopteryx a dinosaur, or ... I don't suppose you'd like to bow to reality and admit that you're wrong, would you?

Edited by Dr Adequate, : No reason given.

Edited by Dr Adequate, : No reason given.


This message is a reply to:
 Message 116 by slevesque, posted 02-05-2010 4:22 PM slevesque has not yet responded

  
Dr Adequate
Member
Posts: 16094
Joined: 07-20-2006
Member Rating: 9.0


Message 134 of 150 (545899)
02-06-2010 4:05 AM
Reply to: Message 114 by slevesque
02-05-2010 4:05 PM


Totally unecessary.

What? It was true. That is, in fact, why you would know if any spurious primitive bird had ever got into the peer-reviewed literature and then been exposed as a hoax. That's how creationists operate. Tell me I'm not calling it how it is.

Therefore, we may rest assured that such a thing has never happened.

---

My remarks are also, I feel, salutary. Consider this. Based on one piece of evidence that paleontologists are professionally competent, you grasp at the conclusion that they're not; based on the fact that they are able to detect a hoax, you wish to believe that so many hoaxes have gotten by them as to entirely vitiate the evidence for bird evolution; based on the fact that (apparently) you trust them completely when they tell you that "Archaeoraptor" was a fake, you seem to be concluding that you need never trust them again; and based on the fact that the peer-review system worked perfectly, you conclude that it is flawed. And all this you base on pointing to just one occasion when you think that they got something right.

This hardly seems fair on them. It would seem rather harsh as a general conclusion if instead you were pointing out that the experts in reptile-bird evolution had got just one thing disastrously wrong. Considering the volume of their work, and the fact that they're human, could they really do better than that? Well, apparently they can. Which is why you are reduced to attacking them by pointing out one occasion on which you seem certain that they were absolutely right.

Edited by Dr Adequate, : No reason given.


This message is a reply to:
 Message 114 by slevesque, posted 02-05-2010 4:05 PM slevesque has not yet responded

  
caffeine
Member
Posts: 1624
From: Prague, Czech Republic
Joined: 10-22-2008
Member Rating: 5.7


Message 135 of 150 (545911)
02-06-2010 9:26 AM
Reply to: Message 109 by Dr Adequate
02-05-2010 12:21 PM


Re: Phylogenetic nitpick
=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."

Wasn't pointing out a problem with your point, just being pedantic with the terminology. To continue a little bit further in that vein, Compsognathus isn't a maniraptoran. Here's the modern understanding of coelurosaur phylogeny (based on Senter (2007), from the wiki page on Coelurosauria:

      ------Tyrannosauroidea
|
|
----- ------Compsognathidae
| |
| |
------ ------Ornithomimosauria
| |
| |
------
|
|
------Maniraptora

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.

Yes, sorry for buggering up the link. I can see this from the abstract, but I was trying to check whether the article claimed that there were preserved impressions of plumulaceous feathers, as google seemed to imply, contra slevesque's claim that no dinosaurs had downy feathers.

Edited by caffeine, : formatting messing up my diagram

Edited by Admin, : Add code dBCode.

Edited by Admin, : Improve diagram.


This message is a reply to:
 Message 109 by Dr Adequate, posted 02-05-2010 12:21 PM Dr Adequate has responded

Replies to this message:
 Message 136 by Dr Adequate, posted 02-06-2010 9:12 PM caffeine has responded

  
Prev1
...
5678
9
10Next
Newer Topic | Older Topic
Jump to:


Copyright 2001-2018 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2019