The Evolution of Birds (Or: What missing link?)

Discussion in 'Biology & Genetics' started by Trippy, Sep 28, 2014.

  1. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    English is his native language. He's just being lazy on his reading. BillyT will likely acknowledge that.

    But he had a good point about bird breathing system. And yes, as I said before and say again, it appears that that 'mystery' is solved, as dinosaurs likely had the similar system as birds (their desecendants) and crocodiles (their distant relatives).

    As to Trippy's original article, there is a 'seamless transition' for every extant species today and their ancient ancestors. We just don't have as good a fossil record for many of them as we've developed for dinosaurs/protobirds/ancientbirds. This is likely because they were so prodigious they left more fossils; and they lived in areas where we've got a good fossilization (such as China)
     
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  3. Trippy ALEA IACTA EST Staff Member

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    That's one word for it.

    Not in my experience.

    No he didn't - the breathing system was one of the features mentioned explicitly in the article.

    This statement manages to completely miss the point of the article.
     
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  5. Trippy ALEA IACTA EST Staff Member

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    The diagram is a phylogenetic diagram - basically it shows the relationships of species. It's showing that Dromaeosaurids, Troodontids, and modern birds had a common ancestor.
    The common ancestor of those groups had a common ancestor with Oviraptorosaurs.
    That common ancestor had a common ancestor with Therizinosaurs and Alvarezsaurs.
    That common ancestor had a common ancestor with Ornithomimosaurs and Compsognathids.
    That common ancestor had a common ancestor with Tyrannosaurs.

    The progression, more or less is as you move from the top of the diagram to the bottom of the diagram.
     
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  7. Trippy ALEA IACTA EST Staff Member

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    And you should not - making statements about what the article had better cover without reading the article is absurd. For all you know it covers that (and the breathing system is, in fact, one of the features that the article considers which makes your comments look even more ridiculous).

    This sentence is bad english. You did not 'tell' two things, you made to statements or you said two things.

    Read the article - for all you know this is covered in it (or the original articles which are linked to from it).

    In species that aren't closely related, sure, but we're not talking about distant relatives here.
     
  8. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    It looks like all other phylogentic diagrams I've seen, but with not as much detail as most. Take a look at plant phylogenetic diagrams, with dozens of intermediaries between top to bottom.

    The point of the article is that there is a good fossil record showing the change from full dinosaur to full bird. But that is what I said in my prior post.
     
  9. Trippy ALEA IACTA EST Staff Member

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    :Roll:
    I thought you said you had read the article? Or did you read the entire article except the image caption which reads "Here’s a simplified version of their phylogenetic relationships"?

    No.

    The point of the article is that there has been an expectation within the paleontological community that there was some kind of missing link between dinosaurs and birds. Finding this has been an area of active research. What the article says is that upon a re-analysis of the fossil record as it currently stands it appears it may actually be complete and that there are no missing links in the transtion from dinosaurs to birds. It also suggests that this is because by the time birds evolved in the fossil record all (or most) of the features we associate with modern birds (one way breathing, air sacs, hollow bones, the wish bone, the keeling of the sternum, the lack of wrist bones, 853 features in 150 species in all) were already in place by the time birds evolved. It goes on to say that these features evolved over a period of tens of millions of years and once they were all in place birds underwent explosive diversification.

    The point of the article is that rather than what we expected to see, which was Dinosaurs -> Intermediate missing link -> Birds, what actually happened was that one particular branch of the dinosaur family tree became increasingly birdy.
     
    Last edited: Sep 29, 2014
  10. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Except I was not expecting a "missing link" as I was already aware of the near-seamless transition in the fossil record, due to the large number of feathered dinos being found in China over the past few decades. Consequently, it did not come as a 'surprise' to me "that there are no missing links in the transtion from dinosaurs to birds", which as I stated "there is a good fossil record showing the change from full dinosaur to full bird", which is essentially what you stated.

    That's not to say that we should quit looking for more feathered dinos, as we can always fill-in between the existing transitional forms, as well as detail the 'dead-end' forms that did not result in true birds, but died out.
     
  11. Trippy ALEA IACTA EST Staff Member

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    Improved oxygen scavenging.

    No it isn't.
    Humans and Octopi are not closely related. Crocodiles and birds are both Archosaurs (the same clade) where Humans and Octopi aren't even the same phyllum (humans are Chordata, Octopi are Mollusca).

    Do I really need to explain this in greater depth, or..?
     
  12. Trippy ALEA IACTA EST Staff Member

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    I'm not sure I was either :shrug: what's your point?

    There's a difference between suspecting something is probably true and being able to demonstrate it conclusively in a repeatable fashion in a peer reviewed journal.

    There you go again with your feather fetish.
     
  13. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Well, your article was all about feathered dinosaurs before they were true birds, was it not? Yes, they have other traits that are somewhat bird-like before they had feathers. But most of the transition shows feathered dinosaurs, which appeared somewhat surprising to paleontologists at the time of their discovery that they were full dinos (not bird-like at all; ie no wings or flight) but covered with feathers. And feather evolution is interesting, though not my 'fetish'
     
  14. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Replying to exchemist's post 16: (for unknown reasons it doe not appear here with pink back ground.)

    I don't care what "researchers BELIEVE MAY HAVE BEEN AN ADVNTAGE." I want some indication that there was one. Certainty there was extra biological cost to build in a system with little or no utility. Of course they MUST believe that if already thinking birds (and or alligators) came from dinosaurs and accept evolution's selection theory.

    For example, most animals (all carnivores, I think) do have a system for making vitamin C, and early ancestors of the primate branch probably had it, but that cost was selected out of their DNA as they got all the vitamin C they needed from their diet. - this information comes to me from the only double winner of the noble prize (I think) - Linus Pauling. He ate 8 grams of vitamin C each day after studies of how much other animals produced per unit of body weight. - how he chose 8 grams.

    There are uncountable number of examples of structure that were once useful being selected against and eliminated. Not one example of structure with no use (but a biological cost) being selected for.

    Yes English* is my native language and I know the important difference between what some "experts believe" and evidence. Do you? Many believe in God - but that is not evidence.

    * I am however a little dyslexic - Interestingly when I re-read my post as I have written them - I often fail to see the errors - read what should be there; however, when I do post, the change in form, sentence length or something makes it easier for me to notice my errors. I also often have let my thoughts get ahead of my typing and words have been left out (doing that to word "not" reverses my intent). So I typically edit my post several times, and not rarely someone replies before my post is in final form.

    Replying to Walter Wagner's post 21 statement " We just don't have as good a fossil record for many of them as we've developed for dinosaurs/protobirds/ancientbirds.":

    The way bird's rib bones are rigidly attached to the back bone should be clear and different from the way that dinosaur's (and man's) are more flexibly attached. - Birds do not expand their chest when breathing but man and dinosaurs do. That change, however, can have viable intermediate stages - the binary switches can not. (like evolving giraffe putting nerve on the other side of bone OR replacing two-way air system with a one-way flow system) This rigidly, only move membrane wall not bones and mussels, is another way that birds use less energy per gram of O2 intake.
     
    Last edited by a moderator: Sep 29, 2014
  15. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Clearly birds, once flight was first obtained, continued to optimize in that direction. Archaeopteryx is considered a 'true bird' though it has many primitive traits not present in modern birds. Did primitive birds have fixed ribs, or did that arise after birds were already flying? Certainly most primitive birds went extinct, and extant birds are derived from one lineage that proved superior to all others primitive birds.
     
  16. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I don't know the answer to any of your questions, Walter. My point is that switching from two way flow to one way flow respiration is a "binary change" impossible for evolution to make in set of small evolutionary steps, each with an advantage. Just like putting the retina in front of the network of blood vessels and signal collection nerves, which join at the "blind spot" in man (retina behind all this) is an impossible binary change - no creature can do that.

    It would have considerable advantages, which the octopus enjoys with a better eye design. Not only more light reaching the retina and no "blind spot" in each eye, but more importantly (I think) much of the neural processing in V1 is for filling in the blood vessel shadow gaps.

    For example when you look at your dog - the optical data of its image sent to the brain is broken into at least 1000 separated "dog parts" by the blood vessel network shadows. - You must fill all these black shadow cuts with best guess of what color etc. was blocked out, in order to perceive a single dog image. - Every glance at any object requires V1 to put together a "jig saw puzzle" of pieces! The octopus brain is spared this task.

    V1's task is much harder than just putting together all the separated tiny image parts of the dog as the 2D image of the dog has other tiny parts next to all the perimeter dog parts. For example the dog may be standing next to a tree. No one is telling V1 that the vertical trunk that in the 2D retinal image which seems to be coming out of the dog's back is not also part of the dog. - You don't know what is making the CONTINUOUS 2D stimulation of retinal cells until much later (out in the temporal lobes) that it is a dog and tree you are looking at.

    To better appreciate the complexity of just parsing the continuous 2D retinal stimulation into discrete objects for later parts of the brain to identify, imagine I gave you a black and white photo taken at a foot ball game showing the field and fans in the stadium on the other side, but I cut that 8 by 10 inch photo in to a set of 100,000 tiny pieces of random shape. Your brain solves this problem several times each second as the dog image parts fall on different parts of the retina with each fixation and all the tiny dog image pieces then have different shapes! God was very kind to the octopus, if evolution is wrong - as his retinal blood supply is behind the retina - Thus dog is one image area, not 5000 tiny odd shaped pieces that differ in shape with each new fixation.
     
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  17. Trippy ALEA IACTA EST Staff Member

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    Billy T you're talking about two seperate changes - the morpheological changes required for the avian flow throigh system of breathing will still work with tidal breathing. From their it's a matter of changing the timing of muscle contractions from tidal breathing to unidirectional flow through. Bidirectional flow through still works in lungs optimized for unidirectional flow through.
     
  18. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    That {"Bidirectional flow through still works in lungs optimized for unidirectional flow through."} may be true but if you have two extra sacks within the chest (one for holding briefly the full intake volume, while the other equally large one contracts to exhale the full stale air breath volume) then your actual lung volume will be greatly reduced - less than half the size it could be without those two additional sacks - that is disadvantage that would be selected AGAINST. If any baby of two-way flow parents were so deformed as to have added two useless sacks it probably would not even be a viable birth defect! Trying to slowly evolve the extra sacks, control system etc, via many generation is equally impossible - no advantage at any tiny step change.

    Hey - You text posted in pink. - Only thing I did differently was to hit the return arrow as I had forgotten to copy the part of your text I made bold above. I.e. I again right clicked on the "reply" next to your post number.
     
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  19. Trippy ALEA IACTA EST Staff Member

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    I'm not sure i accept your argument regarding air-sacs.

    The flipside is that Crocodiles and alligators have been shown to have one way air flow even though they lack air sacs and use diaphramatic breathing.
     
  20. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    BillyT. I re-post Exchemist's link: http://www.thedailybeast.com/articl...-can-t-say-his-spies-underestimated-isis.html#

    It would not have to be a full chamber; a slow change would be very possible, with increasing 2-nd storage space capacity for one-way flow being the optimum.
    Indeed, I suspect that the feathered dinosaurs, which were likely hibh-metabolism and needing to keep warm like mammals, had this fully developed long before the birds arose from them. Fixing the ribs would have been advantageous once flight began, as the flexing was no longer required, and a rigid structure would be advantageous for wing movement.
     
  21. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    oops; wrong link: here is the right one: http://www.newscientist.com/article...y-explain-dinosaurs-triumph.html#.VCg-Fkvlduo

    darn that loss-of-edit function

    Please Register or Log in to view the hidden image!

     
  22. Trippy ALEA IACTA EST Staff Member

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    I don't know about fixed ribs, but unidirectional airflow would certainly ne advantageous for small and/or fast moving dinosaurs.
     
  23. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    yes: "Alligators don't have air sacs like birds, but the researchers think an unusual airway that sits on either side of the alligator trachea may do the same job." Adding sort of side slits like a shark has to allow more rapid exhaling is a beneficial first step so can be selected for. later as a second step letting slight suction close them is also beneficial - you are sort of in the better one way path then.

    In your other post I agree that small (or even large) dinosaurs would benefit form having the more efficient one-way air flow respiration, but so would humans benefit if the retina were in front of instead of behind the neural network collecting signals (and the blind spot where those nerves converge to become the optic nerve) and also in front of the blood supply instead of behind it as their shadows cut the 2D image of each object into many tiny pieces but these are IMPOSSIBLE binary step changes - not small sort of analogue incremental changes that can accumulate over thousand of generations. I.e. add a pair of small air storage sacks (which the alligator could not, and did not, do ) to a two-way air flow system has "negative utility" and would be selected AGAINST. Like wise adding two big ones, all new "plumbing" and new and working control system in one generation would be a very very improbable "hopeful monster." - I.e. would be a fatal birth defect if not a complete functional system.
     

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