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Science

Racing Dinosaurs with Spoilers 60

Posted by michael
from the airdam-optional dept.
PhilHibbs writes "The BBC is reporting a new theory - dinosaurs flapped their proto-wings to generate downforce for added traction when running up-hill. Another one to add to the many theories of the evolution of flight."
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Racing Dinosaurs with Spoilers

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  • Insect flight (Score:4, Interesting)

    by lirkbald (119477) on Friday January 17, 2003 @12:01PM (#5102510)
    One proposal I've heard for the origins of insect wings is as heat collectors. What with all that surface area and the network of veins going through them, insect wings would make good solar collectors. That is, up until the wings got too big, and the heat dissipated before it could get back to the insect's body. But a study showed that just about the time they got too big to work as solar collectors, they'd be big enough to help with gliding.

    It's an interesting theory, but I doubt a similar course could apply to birds. Their wings are covered with feathers, which are mostly just dead skin, and probably wouldn't absorb heat well. Plus birds are warm-blooded, and would have less need for sunning themselves.
    • Re:Insect flight (Score:4, Insightful)

      by Simon Field (563434) on Friday January 17, 2003 @02:11PM (#5103502) Homepage


      Since evolution is still happening all around us, we can look at some of the "proto-wings" we see today and make some inferences.

      We have squirrels that glide out of trees by stretching the skin between their legs.

      We have snakes that do something similar.

      We have flightless birds that still flap their wings when they run.

      We have lizards that stretch membranes much like the flying squirrel. Some of them do it to glide, while others do it to control their temperature.

      If feathers were only for flight, the flightless birds wouldn't have them, and flighted birds would only have them on their wings and tails. We use down for insulation in ski jackets for the same reason the goose made it in the first place.

      A small, warm blooded dinosaur would need insulation. Insulation is lightweight for its bulk, so it would lower the density of the animal as a whole. This would protect the animal from falls, but it would also make it difficult to run, due to the air resistance overcoming the available traction.

      Streamlining would be selected for. Small animals would experience higher Reynolds numbers (the air would seem thicker to them) and so flapping their feathered arms would get them more benefit than a larger animal would get.

      It would not surprise me to find out that flight developed in several dinosaurs in parallel, given that we see it evolving in several quite different critters today (insects, reptiles, mammals, fish).

      Your idea that flight developed as a side effect of temperature control mechanisms doesn't seem far-fetched to me at all. In fact, one might call it near-fletched, if one were a punning fellow.

      • Thanks for the first good explanation I've heard of for feathers appearing in the first place. Any links or resources for further studies on this idea?

        • I did not mean to imply that this was my own idea.

          It has been kicking around for a long time.

          See this article [go.com] for instance.

          Predator-prey ratios and other data have been used to show that some dinosaurs were warm blooded. A small wam blooded dinosaur would have needed some kind of insulation, since the heat is generated by the volume of the animal, but lost through the surface. The smaller the animal, the large the ratio of surface to volume, and thus the larger the heat loss.

      • You are forgetting about loss of function mutations. Today's flightless birds are more likely the result of losing the ability to fly than of a stopping point on the way to developing flight.

        As some birds grew bigger, they no longer had the strength or wingspan to lift themselves off the ground, so they continued to evolve into today's ostriches. Or, flight was no longer needed because predators were scarce and food was plentiful in a certain area, so chickens stopped flying and evolved to put their energy into being fat, laying lots of eggs, and not spending much energy on maintaining wings.

        Looking at current animals for ideas about evolution is great, but remember that groups of organims with great diversity, like birds, are all evolving; they are not stopping points. Kind of like how all dogs started from a generic wolf-like form and humans have bred them into Pomeranians and St. Bernards.

        think on! -clan maclellan


        • Actually, I wasn't forgetting ostriches at all.
          They still flap their wings. So do roadrunners.

          Flight is expensive. Some birds lose the ability not because of size, but because they no longer need to fly. The dodo comes to mind.

          The fact or assumption that the ostrich used to fly is not the point. Look at how it uses its feathers and wings today, and ask yourself if it would be better off without them. If not, then they could be a model for a dinosaur that later evolves into a bird.

      • I agree that feathers definitely originated as some sort of heat-retaining integuement. Look at the assorted flightless feathered dinosaurs that just have a layer of downy "dinofuzz" and it's clear that the integuement was originally insulatory.

        Flight feathers are something different.

        The long, broad, and stiff feathers you see arising in deinonychosaurs and other maniraptors are NOT insulatory, at least, not insulatory as far as keeping the individual animal warm. However, we DO know that maniraptorans minded their nests, often sitting on the nest to keep the eggs warm (fossils of nesting oviraptorids from Mongolia and troodontids from Montana prove that for at least some species). With the manner that they seem to hold their arms in such a nesting position, protoflight feather would be covering the nest, lending to the insulation of the nest. Keep the eggs warmer, you have fewer young that die in the egg, and an evolutionary edge. From these elongated feathers, you may have some of the smaller dinosaurs start gliding and eventually end up with flight.

        Another possibility is as display. We know a lot of maniraptors were at least marginally social and some were much more social (such as Deinonychus). The originally nonfunctional feathers could easily have served as courtship displays. Once again, what was originally NOT a flight mechanism then found use as a gliding and then flight mechanism when other structures formed.

        A third possibility is that feathers acted to help small maniraptors to trap prey. Maniraptors probably relied on their arms and long fingers (and large claws) to catch prey items. Stiff quills might have added a maginally netlike structure that could have given that extra edge on competitors. Eventually, once again, this structure evolved for something else becomes useful for flight and further develops.

        It would not surprise me to find out that flight developed in several dinosaurs in parallel, given that we see it evolving in several quite different critters today (insects, reptiles, mammals, fish).


        I'd actually be less surprised to learn that most maniraptorans are descendants of flying dinosaurs that lost their ability to fly. Too many structures that otherwise don't make sense. Reversed hallux. Certain structures of the feathers, overly-long arms, etc.

        Also, don't mistake gliding for true powered flight. Gliding has evolved countless times (especially in vertebrates). True powered flight has not. Birds, pterosaurs, bats, and insects are the only organisms I can think of that have evolved true powered flight. Whether the flight mechanism has wavered between functional and nonfunctional (as it may have been in early flying dinosaurs/birds) is a totally different question than how many times it independantly arose.
  • Don't you know that God created everything in six days, the world's only 5000 years old, and dinosaurs are planted hoaxes?

    Even reputable news sources [theonion.com] agree.

    P.S. First post.
    • by DrSkwid (118965)
      Don't you know that God created everything in six days, the world's only 5000 years old, and dinosaurs are planted hoaxes?

      There aren't too many places in the English speaking world where that comment would get a "-1 flamebait".

      I guess American Christian Fundamentalism and Islam aren't that far apart after all.

      I think about the only difference is that Islam proscribes family photographs.

      Evolution is just as much a religion as Creationism.

      It just gets better.

      I'm heading for -1 Offtopic or -1 Flambait too I guess.
    • How the hell is this flamebait? It has a link to The Onion fer crissakes. This is supposed to be FUNNY. Shame I used up my last mod points earlier today...
  • has to be the most rediculous theory I have EVER heard. Extra downforce for running uphill??
    • I agree. More likely, they were used for their braking effects going downhill.
      • has to be the most rediculous theory I have EVER heard. Extra downforce for running uphill??
      The extra downforce increases the normal force exerted from the ground on the bird. Friction is proportional to the normal force, and thus provides more traction to allow the bird to run up the slope (rather than allowing the bird to slide back down the slope).

      Think about it... imagine you have a slope with a block that kept sliding down it. If you push down on the block, you can prevent the block from sliding down.

      Learn some physics before you make comments like that. :-P

      • Screw physics, I don't care if it makes sense its still really odd. To paraphrase Calvin (of Calvin & Hobbes): There's no way T-rex was a scavenger because that just wouldn't be cool.
      • The extra downforce increases the normal force exerted from the ground on the bird. Friction is proportional to the normal force, and thus provides more traction to allow the bird to run up the slope (rather than allowing the bird to slide back down the slope).

        Yeah, that's great. Are you really agreeing with the theory that dino's ran uphill SO MUCH that evolution picked the ones that would do it BETTER than the other ones?

        Maybe if they had to run uphill so much, they really got 'wings' to float back down ;) It was a form of protection, see. They'd let a 'sharp-tooth' chase them up a cliff, they would jump off and float to the ground, while the 'sharp-tooth' fell to his death.

        Yeah, that's it ;) Where's my prize?

        • Yeah, that's great. Are you really agreeing with the theory that dino's ran uphill SO MUCH that evolution picked the ones that would do it BETTER than the other ones?

          I said nothing about whether or not I agree with the theory. I was merely correcting his misconception that the downward force doesn't help the bird in moving up the slope. Whether or not this actually helped evolutionarily is another question.

  • Seems a bit weaker than the alternative proposed theories. It would seem to me that extra legs would work better as legs for added traction, not being flapped to create downward force. At least not untill the legs had mutated quite a bit from ordinary legs. Alternative theories like evolution from gliding to flying in tree leaping lizards seems a little more likely path. Although feathers in general still seem a bit of an odditity to me.
  • by Anonymous Coward
    Someone please explain --- flying involves generating lift away from the feet, but racing car spoilers generate downforce into the ground, so shouldn't they create wings of the opposite shape?
    Maybe the important component was forward force rather than footward force, though by bending forward more a small component could be directed footward while most was directed in the direction of motion to get away from the predator.

    The article also did not explain why it wouldn't be more efficient for the creature to use their front legs for additional ground contact, and evolve into a squirrel or lemur. If their arms were too short, they probably wouldn't provide significant force by flapping.
    While arms are good for climbing stiff surfaces like trees, they might be less usful for climbing loose surfaces like sand dunes, or dead-leaf-covered hills in temperate climates, or mud swamps. (If it was dusty, maybe part of the strategy is to blow/flap dust rearward toward the predator?:) Any clues on what the environment was like where these creatures lived?

    • Imagine that you are trying to run fast up a tree. Do you want the 'spoiler' to press your legs against the tree or to pull you away from it?
      • Actually, To run fast uphill or up a tree, I would want really large and strong claws like squarrels use.

        1) it probably is more efficient
        a) don't need the extra muscel mass to flap wings. b) don't need the extra muscel mass to counteract the downward force of the wings. 2) its harder to negotiate around branches if you actaully had wings


        All in all, this is a silly hypothesis. Ever see woodpeckers, flapping their wings to counteract the force that they are pecking the tree with. Just in case you haven't seen a woodpecker, they will hang on to any portion of the tree with their claws, and peck (without flapping their wings :).

        Now that I have stated my opions with my observations, do you know of any modern animals that have evolved to use a spoiler.
  • by Zelet (515452) on Friday January 17, 2003 @01:05PM (#5102952) Journal
    Did they have HUGE tail pipes and make loud vpppppt noises when they run?
  • Does this mean that the next time I'm forced to do that God-awful "Chicken Dance" at a wedding that I can at least take some solace in the fact that I'm actually doing "The Raptor Dance" or "The Tyrannosaurus Rex Dance"?

    GMD

  • that there were ricer dinosaurs?
  • by mkoz (323688)
    One is limited only by imagination as to what series of intermediate stages enabled wings to become as cool as they are. (Okay, there are some biomechanical and developmental constraints).

    Thus is the beauty of doing science without data. Hypotheses are uncontrained.

    At the far extreme:
    Aliens planted diosaurs... disprove it?
    • The world doesn't exist.... disprove it!
    • Isn't it strange that we are looking at mechanical systems as an analogy to living systems. Why not look to modern animals for inspiration. What we have here is a well thought out work based entirely on a sophmoric premise. For example, birds and squarrels can climb all over trees, and when they are climbing trees they either don't have wings or are not using them. They are using their claws (a feature they share with the dinosaurs in question). We all know of the ground effect, where lift generated close to the ground a bit more efficent. My understanding is the it effects airplanes and helicopters. We also know that if you reduce some weight when running or biking, you will accelerate faster with less effort, and you will use less energy so you can go further. This increases a weight to power ratio. Now, if you were in a large area where there were few obsturction, and you wanted to run faster and farther than the preditor comming up, would it not make as much sense to us the claws for traction, the wings to reduce weight (and use the ground effect), and hense, increase you weight to power ratio? Is it just me or does this make more sence the what the pseudo scientist have come up with or beliveing in rael?
  • If this were a valid theory, that added traction is an advantage, then it would seem logical that it would still be true. Thus chickens would flap down not up to get more traction. Watching chickens I see them use their wings for lift to hop further.

    Likewise the era of pre-marsupial when ground birds ruled in the southern americas ought to show skeleton optimized for traction since none of these flew, yet they were predators like dinasours.

    why dont cheetas have wings?
  • Were these *real* race-o-saurs, or were they just crappy street legal dinosaurs that were all hopped up to look like race-o-saurs? In either case, I'd hate to be near when they opened the exhaust on one of these 4-bangers (or 2-bangers, in the case of the bipedes).
  • I could have sworn this was an article about some new "Jurassic Park IV" movie coming out that was crossed with a sequel to "The Fast and the Furious".

    Shit, now I've jinxed it, its going to happen.

It was kinda like stuffing the wrong card in a computer, when you're stickin' those artificial stimulants in your arm. -- Dion, noted computer scientist

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