From Sea to Sky; the Evolution of Birds

Discussion in 'Health and medical' started by Walter Dnes, Apr 10, 2004.

  1. Walter Dnes

    Walter Dnes Guest

    I posted a half-formed theory to this group years ago,
    regarding the evolution of flight in birds. Here it is
    again, this time with a lot more detail, and a lot of loose
    ends cleaned up. The following is a an almost verbatim text
    dump from an essay I've posted on my home page.

    >From Sea to Sky, the Ascent of Birds
    ====================================

    There have been many theories about the origin of aerial
    flight in birds; here's mine. Since Archeopteryx is
    generally recognized as the earliest bird fossil, it's a
    convenient place to start. There has been much speculation
    about how, and for that matter, if, it managed to fly.
    Let's look at what we do know...

    * Archeopteryx did not have the weight-saving
    adaptations of modern
    * birds,
    i.e...
    + it had not lost its teeth
    + it did not have the lightweight bones of modern
    birds
    + it had a real tail which, besides adding extra
    weight and drag, moved its centre-of-gravity well
    behind its wings
    * the wingtips did not have long primary flight feathers.
    * that point was moot, because the shoulder joint did not
    allow the wings to be raised much above horizontal
    * that point was moot, because there was no hole through
    the shoulder joint through which to pass the large
    tendon that gives the rapid and powerful wing upstroke
    in living birds
    * and that point was also moot, because it lacked the
    prominent breastbone of modern birds, onto which to
    attach large muscles to contract those tendons.

    To summarize...

    1. It was too heavy to be a glider. Gliding also implies
    climbing up some structure in order to be able to jump
    off it. The desparate attempts to picture a "bird"
    clawing it's way up a tree are laughable. That fact that
    the paleo-climate of the Solnhofen Lagoon district
    during Archeopteryx's time was desert-like, with no
    large trees in the vicinity, should help kill that idea.

    2. As for powered (i.e. flapping) flight, it didn't have
    the breastbone to which to attach muscles to contract
    the tendons it didn't have, which didn't pass through
    the holes that it didn't have in its shoulders, which
    didn't have the joints to allow flapping of its wings,
    which didn't have long primary flight feathers.

    3. And in any case, the claws on the leading edge of its
    wings would destroy the aerodynamic airflow, and the
    long bony tail would push the centre-of-gravity well
    back of the wings.

    Archeopteryx never flew; deal with it.

    Could Archeopteryx be a flightless descendant of a bird
    that flew? Since Archeopteryx is the earliest known
    feathered and winged fossil, that seems rather unlikely.
    That idea would also require totally insane reverse-
    evolution, i.e. the shoulder joint reverting to theropod
    style, and the return of teeth. So we can safely
    conclude that none of Archeopteryx's immediate ancestors
    flew, either.

    Well, if none of Archeopteryx's immediate ancestors flew,
    that implies that it evolved aerodynamic feathers (picky,
    picky, picky) and wings for reasons other than aerial
    flight (picky, picky, picky). Any theory of the evolution
    of aerial flight in birds must address that issue. It
    would also be nice to be able to explain how the first
    attempts at flight could result in crash-landings without
    killing the bird, or maiming it to the point where it was
    unable to fend for itself, and starved to death, if it
    wasn't eaten by a predator.

    My theory starts off with a feather-covered theropod that
    is ancestral to Archeopteryx. For anybody who doesn't like
    that idea, I refer you to Sinosauropteryx, Caudipteryx,
    Shuvuuia, Sinornithosaurus, Beipiaosaurus, etc. Here is
    how I propose things went...

    4. We start off with pre-Archeopteryx, a small, bipedal
    theropod with forelimbs like those of Coeleurosaur. It
    has an insulating coat of feathers.

    5. Pre-Archeopteryx discovers that plants, crustaceans, and
    even the occasional fish along the shore are delicious.
    This discovery may have been accelerated by climate
    change which reduces food supply away from the shore. In
    pursuit of its food, it starts spending more and more
    time in the water.

    6. What happens to land-dwelling vertebrates that start
    spending a lot of time in water? Riiiiiiiight! Their
    limbs tend to evolve into flippers. Our feathered,
    bipedal, theropod's forelimbs start looking like wings.
    Part way through the process, it will still have some
    claws on the leading edge of the flippers. Since it
    still spends some significant time on land, it's feet
    will still be that of a land animal. It's a bird, it's a
    plane, no it's our friend Archeopteryx.

    Things start making sense now. The reason that we find
    Archeopteryx's fossils only in a lagoon, is because it
    was a flightless feathered theropod that spent quite a
    bit of time in water. A flightless bird/theropod that
    spends a lot of time in water doesn't have to worry
    about shedding teeth to reduce weight. Claws on its
    wings can be used to grab fish or other prey. The fact
    that its feathers aren't suited for flight is moot.
    Their purpose is to keep the animal warm, and not get
    in the way when it runs around in the water. What
    little swimming it does probably consists of breast-
    stroke or dog-paddle, because it doesn't have bird-type
    shoulder joints.

    7. A few million years pass. After spending even more time
    in water, adaptations continue. The feet get webbed and
    the shoulder joints evolve to a bird-like mode to allow
    raising its forelimbs above its shoulders. This allows a
    more powerful underwater swimming stroke; actually
    "flying underwater". To supply the necessary power, it
    needs stronger muscles, and a place to attach them to
    (keelbone). Now that it's wings are used for "flying
    underwater", "flight feathers" start to be an advantage.
    Since it hasn't yet flown aerially, there is no
    advantage to shedding its teeth. Hesperornis would be a
    reasonable specimen of this stage. Our flightless bird
    spends a lot of time "flying underwater". It learns to
    navigate in 3 dimensions, which will be important later.

    The Avian Kitty Hawk
    --------------------

    A Hesperornis-like "flightless" bird is minding its own
    business one day when along comes a big fish, or whatever,
    that thinks of our bird friend as a yummy meal. It gives
    chase and the bird flees, with rapid frantic wing-strokes.
    Since it's an air-breathing animal, it needs to surface to
    breathe. It's moving as fast as it can to escape its
    predator, so that it not only gets to the surface, but
    most of its body gets clear out of the water. Since it's
    being pursued, it keeps flapping its wings... and flies
    several metres before landing back in the water, giving
    itself enough of an advantage to get to shore safely.

    Having discovered flight and its survival value, water-
    birds were able to able to parlay their "underwater-
    flying" skills to aerial flight. Crash-landing in the
    water after getting one or two metres into the air is a
    lot less likely to kill/maim a bird than crash-landing on
    hard land. Landing on floating logs, and then on branches
    of floating logs will be the next step in acquiring tree-
    landing skills, without killing themselves if they don't
    do it exactly right the first time.

    Birds didn't evolve aerodynamic feathers for the purpose
    of aerial flight, they evolved hydrodynamic feathers for
    the purpose of underwater flight; yeah, picky, picky,
    picky. Yes, I have read Elaine Morgan's book "Descent of
    Woman". Read into that what you will.

    --
    Walter Dnes; my email address is *ALMOST* like
    wzaltdnes@waltdnes.org Delete the "z" to get my real
    address. If that gets blocked, follow the instructions at
    the end of the 550 message.
     
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  2. Tim Tyler

    Tim Tyler Guest

    "Walter Dnes (delete the 'z' to get my real address)" <wzaltdnes@waltdnes.org> wrote or quoted:

    > I posted a half-formed theory to this group years ago,
    > regarding the
    > evolution of flight in birds. Here it is again, this time
    > with a lot
    > more detail, and a lot of loose ends cleaned up. The
    > following is a
    > an almost verbatim text dump from an essay I've posted on
    > my home page.

    http://www.waltdnes.org/essays/birdflight.html

    > Birds didn't evolve aerodynamic feathers for the purpose
    > of aerial flight, they evolved hydrodynamic feathers for
    > the purpose of underwater flight; yeah, picky, picky,
    > picky. Yes, I have read Elaine Morgan's book "Descent of
    > Woman". Read into that what you will.

    The "aquatic bird theory":

    ``My idea (attention, only idea, not evidence!) about the
    beginning of feathers is:

    If the hypothesis of a beginning to thermal retention
    based on feather insulation is accepted in(parcial or not)
    endogenotermic, fast and agile protoavians, we must
    consider this adaptation as relating to those causes which
    would favour body heat dissipation.

    This presumed heat loss must have been linked to an
    important biological function, as if not, the appearance
    of feathers would not have prospered. It is possible that
    this function might have, among other possibilities,
    concerned obtaining food, its source and the feeding
    methods used. Among the divers biotopes which presented a
    varied fauna there were lakes, pools and marshes, where
    there could have been no lack of larvae, aquatic insects,
    molluscs, crustaceans (remember Eoalulavis hoyasi), fish
    and amphibians.

    We can imagine a small group of protoavian theropods
    beginning predatory incoursions into the water. Continuous
    invasions of the water in search of food, would tend to
    reduce corporal temperature, encouraging insulatin,
    waterproof feather covering, devired from special type of
    scale, to preserve the animal's thermal balance...

    With regard to this it is also interesting to observe a
    significant porportion of Early Cretaceous fossil birds
    are related to aquatic environments...

    Some references: *The evolution of Feathers* Jan Dyck.
    Zoologica Scripta.1985

    *Hypothetical begginnings of feathers in continental
    aquatic palaeoenvironments"* A.Lacasa. Terra Nova 1993.''

    - http://www.cmnh.org/dinoarch/1996Oct/msg00116.html
    --
    __________
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  3. << ur flightless bird spends a lot of time "flying
    underwater". It learns to navigate in 3 dimensions, which
    will be important later. >>

    What about this - its a shore animal that has learned to
    escape by flying/swimming out to sea. By going 10 feet out
    it would save it from most land animal danger.
     
  4. Walter Dnes

    Walter Dnes Guest

    On Mon, 12 Apr 2004 23:04:59 +0000 (UTC), TomHendricks474, <tomhendricks474@cs.com> wrote:
    > << ur flightless bird spends a lot of time "flying
    > underwater". It learns to navigate in 3 dimensions, which
    > will be important later. >>
    >
    >
    > What about this - its a shore animal that has learned to
    > escape by flying/swimming out to sea. By going 10 feet
    > out it would save it from most land animal danger.

    Forelimbs morphing from coeleurasaur-like arms into flipper-
    like wings implies that Archeopteryx (and/or its
    ancestors) spent a *SIGNIFICANT* amount of time in water.
    Significant enough that having hydrodynamic flippers was
    more important to survival than having forearms that can
    pick up small objects. Occasional wading into shallow
    water seems a weak driver for that type of evolution.

    --
    Walter Dnes; my email address is *ALMOST* like
    wzaltdnes@waltdnes.org Delete the "z" to get my real
    address. If that gets blocked, follow the instructions at
    the end of the 550 message.
     
  5. Walter Dnes

    Walter Dnes Guest

    What can I say; great minds think alike <g>. Both of those
    dates (the book and the mailing list posting) preceeded my
    original posting of 1997/06/22 (according to Google).

    --
    Walter Dnes; my email address is *ALMOST* like
    wzaltdnes@waltdnes.org Delete the "z" to get my real
    address. If that gets blocked, follow the instructions at
    the end of the 550 message.
     
  6. Jim Menegay

    Jim Menegay Guest

    "Walter Dnes (delete the 'z' to get my real address)" <wzaltdnes@waltdnes.org> wrote in message news:<c5abhg$21qo$1@darwin.ediacara.org>...
    > Birds didn't evolve aerodynamic feathers for the purpose
    > of aerial flight, they evolved hydrodynamic feathers for
    > the purpose of underwater flight;

    The "obvious" solution to the fluid dynamics problem is to
    stretch a membrane between ribs. Nature has rediscovered
    this many times in both a hydrodynamic context (fish fins,
    whale fins, duck feet) and an aerodynamic context (insect
    wings, bat wings, and probably reptile wings).

    Once in evolution, Nature has discovered an alternate
    solution to the aerodynamic problem - feathers. That
    feathers actually work in this context, and that Nature
    could have discovered this, seems almost a miracle - it is
    certainly in need of explanation.

    The proposed explanation strikes me as invoking a second,
    greater miracle to explain the first - that feathers
    actually also work in a hydronomic context, that Nature
    could have discovered this, and that She would then have
    abandoned this technology in favor of stretched membranes
    for modern diving birds.
     
  7. Tim Tyler

    Tim Tyler Guest

    Jim Menegay <jimmenegay@sbcglobal.net> wrote or quoted:
    > "Walter Dnes (delete the 'z' to get my real address)"
    > <wzaltdnes@waltdnes.org> wrote in message
    > news:<c5abhg$21qo$1@darwin.ediacara.org>...

    > > Birds didn't evolve aerodynamic feathers for the
    > > purpose of aerial flight, they evolved hydrodynamic
    > > feathers for the purpose of underwater flight;
    >
    > The "obvious" solution to the fluid dynamics problem is to
    > stretch a membrane between ribs. Nature has rediscovered
    > this many times in both a hydrodynamic context (fish fins,
    > whale fins, duck feet) and an aerodynamic context (insect
    > wings, bat wings, and probably reptile wings).
    >
    > Once in evolution, Nature has discovered an alternate
    > solution to the aerodynamic problem - feathers. That
    > feathers actually work in this context, and that Nature
    > could have discovered this, seems almost a miracle - it is
    > certainly in need of explanation.
    >
    > The proposed explanation strikes me as invoking a second,
    > greater miracle to explain the first - that feathers
    > actually also work in a hydronomic context, that Nature
    > could have discovered this, and that She would then have
    > abandoned this technology in favor of stretched membranes
    > for modern diving birds.

    The source I mentioned offered thermoregulation as a partial
    explanation.

    Instead of growing a layer of under-skin fat, they grew a
    layer of above-skin hair. This trapped an insulating layer
    of air when underwater - and could be effectively
    waterproofed using oils.

    The insulating laker of air may be the key factor. Look at
    how high ducks are in the water. They have an underwater air
    cushion supporting them - which keeps most of their body out
    of the water.

    In addition, they have a light skeleton - which further
    lowers the water line. Keeping your body out of the water
    has the obvious plus point of stopping your heat from
    draining away.

    As it turned out, both feathers and light bodies turned out
    to have some other uses as well.

    Thermoregulation is one of the conventional explanations for
    feathers - though relatively few people seem to have made
    the aquatic link. Another

    practically anything.
    --
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  8. Jim Menegay

    Jim Menegay Guest

    Tim Tyler <tim@tt1lock.org> wrote in message news:<c5m9cj$30d9$1@darwin.ediacara.org>...
    > The source I mentioned offered thermoregulation as a
    > partial explanation.

    I fully agree. Feathers arose for insulation and only later
    were adapted to flight. In fact, I would guess that birds
    were already flying before they began to optimize their
    wings by shifting more and more of the aerodynamic load-
    bearing function from the skin to the feathers.

    > Instead of growing a layer of under-skin fat, they grew a
    > layer of above-skin hair. This trapped an insulating layer
    > of air when underwater - and could be effectively
    > waterproofed using oils.
    >
    > The insulating laker of air may be the key factor. Look at
    > how high ducks are in the water. They have an underwater
    > air cushion supporting them - which keeps most of their
    > body out of the water.
    >
    > In addition, they have a light skeleton - which further
    > lowers the water line. Keeping your body out of the water
    > has the obvious plus point of stopping your heat from
    > draining away.

    Yes, but it has the disadvantage of making it very difficult
    to dive. But ducks are excellent divers. Anyone know how
    they manage that?
     
  9. Walter Dnes

    Walter Dnes Guest

    On Thu, 15 Apr 2004 03:57:37 +0000 (UTC), Jim Menegay, <jimmenegay@sbcglobal.net> wrote:
    > "Walter Dnes (delete the 'z' to get my real address)"
    > <wzaltdnes@waltdnes.org> wrote in message
    > news:<c5abhg$21qo$1@darwin.ediacara.org>...
    > > Birds didn't evolve aerodynamic feathers for the
    > > purpose of aerial flight, they evolved hydrodynamic
    > > feathers for the purpose of underwater flight;
    >
    > The "obvious" solution to the fluid dynamics problem is
    > to stretch a membrane between ribs. Nature has
    > rediscovered this many times in both a hydrodynamic
    > context (fish fins, whale fins, duck feet) and an
    > aerodynamic context (insect wings, bat wings, and
    > probably reptile wings).
    >
    > Once in evolution, Nature has discovered an alternate
    > solution to the aerodynamic problem - feathers. That
    > feathers actually work in this context, and that Nature
    > could have discovered this, seems almost a miracle - it
    > is certainly in need of explanation.

    *FEATHERS WERE AROUND BEFORE WINGS*. See Sinosauropteryx,
    Caudipteryx, Shuvuuia, Sinornithosaurus, and
    Beipiaosaurus. The implication is that the ancestors of
    birds, just like birds themselves, were endothermic. And
    feathers were their analogue to hair/fur.

    Spending lots of time in water tends to cause four-
    footed animals' limbs to evolve back into flippers. In
    this case, the forelimbs evolved into feather-covered
    flippers (i.e. wings). The feet of bipedal animals are
    another issue. I believe that Archeopteryx was a
    transitional phase, and that their descendants would
    eventually develope webbed feet if they didn't leave the
    water first.

    --
    Walter Dnes; my email address is *ALMOST* like
    wzaltdnes@waltdnes.org Delete the "z" to get my real
    address. If that gets blocked, follow the instructions at
    the end of the 550 message.
     
  10. Tim Tyler

    Tim Tyler Guest

    Jim Menegay <jimmenegay@sbcglobal.net> wrote or quoted:
    > Tim Tyler <tim@tt1lock.org> wrote in message
    > news:<c5m9cj$30d9$1@darwin.ediacara.org>...

    > > The insulating laker of air may be the key factor. Look
    > > at how high ducks are in the water. They have an
    > > underwater air cushion supporting them - which keeps
    > > most of their body out of the water.
    > >
    > > In addition, they have a light skeleton - which further
    > > lowers the water line. Keeping your body out of the
    > > water has the obvious plus point of stopping your heat
    > > from draining away.
    >
    > Yes, but it has the disadvantage of making it very
    > difficult to dive. But ducks are excellent divers. Anyone
    > know how they manage that?

    I expect this sentence gives a clue:

    ``Grebes are diving birds that can plunge headfirst
    underwater and sink slowly out of sight by compressing their
    feathers and driving out trapped air.''

    Diving birds quite likely have feathers which can be
    controlled - and can squeeze trapped air out if they want to
    - perhaps with a wriggle as well to shake the bubbles off.
    --
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  11. "Walter Dnes (delete the 'z' to get my real address)"
    <wzaltdnes@waltdnes.org> wrote in news:c5abhg$21qo$1@darwin.ediacara.org:

    (snip)

    > Having discovered flight and its survival value, water-
    > birds were able to able to parlay their "underwater-
    > flying" skills to aerial flight. Crash-landing in the
    > water after getting one or two metres into the air is
    > a lot less likely to kill/maim a bird than crash-
    > landing on hard land. Landing on floating logs, and
    > then on branches of floating logs will be the next
    > step in acquiring tree-landing skills, without
    > killing themselves if they don't do it exactly right
    > the first time.

    A problem with this hypothesis is that fluid mechanics in
    air and water are very different, because air is a
    compressible fluid while water is not. This means that
    structures and mechanics that work well in water may not
    work particularly well in air. After being around for
    several hundred million years, there are no true flying fish
    - only gliders. And some birds that are very aquatic -
    penguins - don't fly. These criticisms don't disprove your
    hypothesis, but if you are serious about your hypothesis, I
    think you need to address this question.

    Yours,

    Bill Morse
     
  12. Tim Tyler

    Tim Tyler Guest

    William Morse <wdmorse@twcny.rr.com> wrote or quoted:
    > "Walter Dnes (delete the 'z' to get my real address)"
    > <wzaltdnes@waltdnes.org> wrote in
    > news:c5abhg$21qo$1@darwin.ediacara.org:

    > > Having discovered flight and its survival value, water-
    > > birds were able to able to parlay their "underwater-
    > > flying" skills to aerial flight. Crash-landing in the
    > > water after getting one or two metres into the air is
    > > a lot less likely to kill/maim a bird than crash-
    > > landing on hard land. Landing on floating logs, and
    > > then on branches of floating logs will be the next
    > > step in acquiring tree-landing skills, without killing
    > > themselves if they don't do it exactly right the first
    > > time.
    >
    > A problem with this hypothesis is that fluid mechanics in
    > air and water are very different, because air is a
    > compressible fluid while water is not. This means that
    > structures and mechanics that work well in water may not
    > work particularly well in air. After being around for
    > several hundred million years, there are no true flying
    > fish - only gliders. And some birds that are very aquatic
    > - penguins - don't fly. These criticisms don't disprove
    > your hypothesis, but if you are serious about your
    > hypothesis, I think you need to address this question.

    It seems like a "true" flying fish would have to learn to
    breathe air.

    That's probably quite a challenge.

    Some birds can function in the air and the water - but
    they learned to breate air on land before they mastered
    the trick.
    --
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