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Author Topic:   Evolution of bird lungs from reptile lungs impossible?
Andya Primanda
Inactive Member


Message 1 of 33 (218605)
06-22-2005 5:11 AM


Recently I am stumped by a challenge posed from a creationist in my local evolution mailing list. The creationist said that bird lungs cannot evolve from reptile-lungs, due to very different designs. Reptile lungs, like our mammalian lungs, has only one air passage in which air comes in and out, while modern bird lungs has two passages, for the inflow and outflow of air. The argument mainly comes from here http://www.harunyahya.com/evolutiondeceit06.php under the heading 'Special Lungs for Birds'.

Naturally I would look for some studies concerning possible evolutionary scenarios for this, but so far I've been disappointed because the only ref I found is this

Ruben, John A, et al (1997). Lung Structure and Ventilation in Theropod Dinosaurs and Early Birds. Science 278(5341): 1267-1270.

(Link to html version of Ruben et al 1997):
http://cas.bellarmine.edu/tietjen/images/lung_structure_and_ventilation_i.htm

in which the authors claim this:

"Recently, conventional wisdom has held that birds are direct descendants of theropod dinosaurs. However, the apparently steadfast maintenance of hepatic-piston diaphragmatic lung ventilation in theropods throughout the Mesozoic poses fundamental problems for such a relationship. The earliest stages in the derivation of the avian abdominal air sac system from a diaphragm-ventilating ancestor would have necessitated selection for a diaphragmatic hernia 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."

which adds to the difficulty because birds are now also supposed to have lost the diaphragm-ventilating condition.

Also, I am not too familiar with bird anatomy so I cannot tell if the argument itself is valid. Do birds actually have that kind of lung?

So should we admit defeat to creationists on this point, or does anyone know how to refute it? Please don't suggest that I use the 'lungs don't fossilise' argument, as this will only be seen as evading the challenge.

This topic would go into 'Biological Evolution'.

This message has been edited by Andya Primanda, 06-22-2005 05:18 AM


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AdminNosy
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From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 2 of 33 (218646)
06-22-2005 10:51 AM


Thread moved here from the Proposed New Topics forum.
  
Dr Jack
Member (Idle past 271 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 3 of 33 (218657)
06-22-2005 11:21 AM
Reply to: Message 1 by Andya Primanda
06-22-2005 5:11 AM


Reptile lung's (scroll down a bit)
Bird lungs

As you can see there are clear similarities and clear differences - the important one for birds is the direct and valved connection to the air sacs (incidently air sacs are present in many reptiles, for example, in snakes). I don't think it's actually that hard to see a evolutionary path between the two:

Initially birds evolve to breath by expanding/contracting the air sacs rather than the lungs: this is beneficial because it frees the cycle of breathing from the beat pattern of the winds.

Valves evolve at the front of the lung allowing air out but not in, meaning that air now follows a more circular path with less mixing with used air. This is directly beneficial in terms of oxygen requirements.

More valves evolve at the back of the lung to keep the air more efficently in the lungs during their contraction phase.

This system resembles the modern one, we have respiration drawing air into the posterior air sacs and then pushing them through the lungs. However the air is not yet being cleared from the lungs so some efficency is lost in mixing.

The development of anterior air sacs helps by pulling the used air out as the fresh air comes in, their placement naturally allows the used air to be blown out through the forward valve as the sacs contract but mixing will still occur as some will go back the way it came albeit at a reduced level

We're now almost there; the final stage is to add more valves to the system to prevent the re-entry of used air into the posterior sacs from the lung and the re-entry of used air from the anterior sacs to the lung. Both these adaptations have immediate benefits in terms of reducing mixing. And the system now naturally switches to the two-stage, unidirectional breathing pattern of modern birds.

This is of course pure speculation, but so is the claim that it can't evolve. Anyone see any glaring errors in the pathway I describe above?


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Replies to this message:
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Dr Jack
Member (Idle past 271 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 4 of 33 (218954)
06-23-2005 11:47 AM
Reply to: Message 1 by Andya Primanda
06-22-2005 5:11 AM


The earliest stages in the derivation of the avian abdominal air sac system from a diaphragm-ventilating ancestor would have necessitated selection for a diaphragmatic hernia in taxa transitional between theropods and birds.

Just noticed this in the quote. Reptiles don't have diaphragms, that's mammals - reptiles breath purely by motion of the ribs.


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deerbreh
Member (Idle past 1058 days)
Posts: 882
Joined: 06-22-2005


Message 5 of 33 (219027)
06-23-2005 2:29 PM


Reptiles are not a monophylogenic Group
My memory is a little sketchy about all of this but one thing I do remember is that reptiles are polyphylogenic - that is they do not have a recent common ancestor. They are kind of a catch-all group with some of the grouping based on derived rather than acquired characters. In other words, it is not particularly helpful to talk about birds evolving from reptiles - which reptile? Furthermore, it is not clear how closely related dinosaurs were to current extant reptiles. Furthermore, this whole discussion seems to be veering into the logical fallacy of "argument from ignorance" - if we can't logically explain it, it didn't happen. Lungs and circulatory systems are soft body parts - they don't fossilize well. So it is difficult to extrapolate much about lung morphology of extinct ancestors/relatives. I would think about the best we could do is use DNA analysis to establish the closest extant relatives (presumably some "reptile") of birds and go from there.
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Chiroptera
Member
Posts: 6626
From: Oklahoma
Joined: 09-28-2003
Member Rating: 4.8


Message 6 of 33 (219060)
06-23-2005 3:30 PM
Reply to: Message 5 by deerbreh
06-23-2005 2:29 PM


Re: Reptiles are not a monophylogenic Group
Since birds are not usually classified as reptiles it is true that reptiles are not monophylogenic.

However, the majority concensus is, I believe, that the synapsids (mammals ancestors) split from the amniote line earlier than the diapsids (turtles) and anapsids (other reptiles) split from each other. It is possible to define reptiles to be the crown group of turtles and lizards. In that case, birds would be reptiles by definition.


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Dr Jack
Member (Idle past 271 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 7 of 33 (219235)
06-24-2005 4:42 AM
Reply to: Message 5 by deerbreh
06-23-2005 2:29 PM


Re: Reptiles are not a monophylogenic Group
I believe the usual claim is that birds evolved from Dinosaurs (specifically theropods) who's lungs, of course, we cannot identify. However we do know that the lungs of the extant groups that diverged from the common line shared with the dinosaurs all use the same pattern of lung design so unless all these groups happened to seperately evolve the same lung design dinosaurs must have started with the same lung design - at which point it becomes moot whether the "bird" lung evolved in the bird lineage or the dinosaur lineage.
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Andya Primanda
Inactive Member


Message 8 of 33 (219243)
06-24-2005 7:38 AM


Thanks Mr. Jack. Somehow I get the impression (from that Harun Yahya page) that birds have two separate windpipes. Of course this is not true (I should confirm this... *slaughters a nearby pigeon*).

I'll see if I can get this to my opponent.


  
Chiroptera
Member
Posts: 6626
From: Oklahoma
Joined: 09-28-2003
Member Rating: 4.8


Message 9 of 33 (219328)
06-24-2005 12:44 PM
Reply to: Message 7 by Dr Jack
06-24-2005 4:42 AM


Re: Reptiles are not a monophylogenic Group
I might add that the closest extant relatives to birds are believed to be the crocodiles (classed together as Archosaurs). It appears that modern crocodiles have certain features in the heart and lungs in common with modern birds.
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deerbreh
Member (Idle past 1058 days)
Posts: 882
Joined: 06-22-2005


Message 10 of 33 (219399)
06-24-2005 5:27 PM
Reply to: Message 9 by Chiroptera
06-24-2005 12:44 PM


Does that mean crocs are a transitional species?
That should rock the socks of the "no transitional species" crowd.
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Chiroptera
Member
Posts: 6626
From: Oklahoma
Joined: 09-28-2003
Member Rating: 4.8


Message 11 of 33 (219405)
06-24-2005 5:53 PM
Reply to: Message 10 by deerbreh
06-24-2005 5:27 PM


Re: Does that mean crocs are a transitional species?
Hello, deerbreh.

Unfortunately, I am not an expert in this stuff by any means. I only know what I gleen out of magazines, books, and a few internet pages.

I love the Palaeos website. Not only does it have some cool cladograms, but it is full of fun information. I only wish I knew how much of the information reflects the scientific consensus and how much of it is the authors favored theories. But it really is a great site.

It has a nice page describing the history and problems of sorting out the phylogenies of the archosaurs. But it seems to claim that the Euparkeriidae were close to being a basal archosaur. It seems that the Euparkeriidae were already beginning down the road to what we think of "dinosaur-looking" -- the crocodile line then took a turn to becoming "lizard-like" again.

The top picture on this page has an artist's rendition of a euparkeriidan.

Cheers!


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Andya Primanda
Inactive Member


Message 12 of 33 (220628)
06-29-2005 7:14 AM


Update from me. My opponent claimed the whole bird respiratory system is IC. But I managed to defuse his IC argument [he claimed birds cannot fly without the one-way airflow system] by pointing that bats don't have them, and they still fly. Still awaiting answer from him for that one.
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Dr Jack
Member (Idle past 271 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 13 of 33 (220633)
06-29-2005 8:38 AM
Reply to: Message 12 by Andya Primanda
06-29-2005 7:14 AM


Any chance of a link to your discussion, Andya?
This message is a reply to:
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deerbreh
Member (Idle past 1058 days)
Posts: 882
Joined: 06-22-2005


Message 14 of 33 (220659)
06-29-2005 10:57 AM
Reply to: Message 12 by Andya Primanda
06-29-2005 7:14 AM


Bats are an excellent example of convergent evolution.
In my opinion convergent evolution is the biggest problem the creationists (and fellow travelor IDers)have. As soon as it can be shown that a problem (in this case sustained flight) can be solved in more than one way, it makes the irreducible complexity idea all the more untenable.
This message is a reply to:
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Andya Primanda
Inactive Member


Message 15 of 33 (220902)
06-30-2005 8:08 AM
Reply to: Message 13 by Dr Jack
06-29-2005 8:38 AM


Can you read Bahasa Indonesia?
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