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Reanalysis of 4-Winged Dinosaur May Illuminate Evolution of Bird Flight

The views expressed are those of the author and are not necessarily those of Scientific American.


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Microraptor gui

Model of Microraptor gui, a feathered dinosaur. Image: David Krentz

RALEIGH, N.C.—How did the ancestors of birds evolve the ability to fly? That birds are descended from small, meat-eating dinosaurs is established. Exactly how the creatures conquered the air remains a mystery, however. Now the authors of a new study of a controversial feathered dinosaur say they have resolved a key aspect of the problem—namely, how the animals controlled their flight once they became airborne.

Two theories have dominated the long-running debate over how bird flight evolved. In the so-called cursorial scenario, the ability to fly emerged in terrestrial dinosaurs that raced across the ground with their arms outstretched and leaped into the air after prey or out of harm’s way, their wing feathers providing lift. The arboreal scenario, in contrast, supposes that flight arose in tree-dwelling dinosaurs that were built for gliding and started flapping their arms in order to stay aloft longer.

Microraptor gui fossil

Fossil of feathered dinosaur Microraptor gui. Image: David W. E. Hone, Helmut Tischlinger, Xing Xu, Fucheng Zhang, via Wikimedia Commons

In 2003 a feathered dinosaur fossil came to light that was purported to elucidate the question of how flight evolved. The roughly 125-million-year-old specimen exhibited evidence of feathers on its hind limbs in addition to its forelimbs, prompting researchers to describe the crow-size animal, Microraptor gui, as a four-winged dinosaur. A startling artist’s reconstruction accompanied the description of the fossil remains, showing the bird flying with its hindlimbs spread out to the side, as if doing a split. The authors argued that the feathered hindlimbs, together with the forelimb wings, acted as an airfoil to help the animal glide. Critics begged to differ.

The new work paints a different picture of how Microraptor’s enigmatic hindlimbs functioned. In two presentations given on October 20 at the annual meeting of the Society of Vertebrate Paleontology (SVP) in Raleigh, N.C., Michael Habib and Justin Hall of the University of Southern California argued that the hindlimbs would have been generally held under the body during steady flight and then deployed to produce rotation movement (roll) or left-right movement (yaw) during unsteady maneuvers such as turning. The team reported that its mathematical modeling indicates that Microraptor’s hindwings would have enabled it to turn twice as fast as a two-winged animal—handy for dodging trees in its cluttered environment. Complimenting the hindlimb’s role in turning and braking, the tail of Microraptor controlled up-down movement (pitch), the researchers say. “A combination of pitch control by the tail, roll generation by the ‘hindwings’ and multi-purpose control by the main wings would have made Microraptor a highly maneuverable animal,” Habib noted.

Microraptor gui

Microraptor gui. Image: David Krentz

“This study provides a plausible mechanism by which dinosaurs that otherwise have strongly Velociraptor-like bodies could take to the air and control themselves while in flight,” Hall remarked in a statement to the press. “Obviously crashing is bad for the long-term health of the animal, but until now we had little idea how the earliest flying dinosaurs avoided such catastrophes given their relatively simple wing structure.” Habib added that this so-called distributed control system may have been an independent experiment in flight that had no bearing on the evolution of bird flight, or that it could represent an intermediate phase in the evolution of bird flight, after which most control function shifted to the forelimbs. The presentations were co-authored by David Hone of the Queen Mary, University of London, and Luis Chiappe of the Natural History Museum of Los Angeles County.

Not everyone is convinced by the team’s arguments. Kevin Padian of the University of California at Berkeley, an expert on bird evolution, observed that the presentations focused on the effect of the hindlimb on a gliding animal instead of one that flapped its wings. Last year at the SVP meeting he presented evidence that gliders and flyers are completely unrelated to each other. He says that “there is not a shred of evidence that says gliding is involved in the evolution of flapping flight.” He questioned why the team’s model would focus on gliding parameters when the forelimb shape was consistent with flapping, not gliding, and the hindlimb would have generated so much drag.

 

About the Author: Kate Wong is an editor and writer at Scientific American covering paleontology, archaeology and life sciences. Follow on Twitter @katewong.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. Bird/tree/dinosaur/etc. geek 9:27 am 10/24/2012

    Interesting article–I have seen the legs-over-the-tail model work plausibly, as well, though. Are there any updates about its possible capabilities of powered flight?

    Warning to all BANDits who post here (Alan Feduccia, that means YOU and your minions!): I will disassemble trolls like you with unholy glee.

    Link to this
  2. 2. ErnestPayne 4:47 pm 10/24/2012

    A four winged dinosaur? Is this story a canard?

    Link to this
  3. 3. kwong 5:00 pm 10/24/2012

    I see what you did there, ErnestPayne–clever!

    Link to this
  4. 4. Bird/tree/dinosaur/etc. geek 9:04 am 10/25/2012

    Good pun, ErnestPayne.

    Link to this
  5. 5. Bill_Crofut 3:59 pm 10/25/2012

    Re: “That birds are descended from small, meat-eating dinosaurs is established.”

    On what basis has the descent of birds from dinosaurs been established?

    Link to this
  6. 6. Bird/tree/dinosaur/etc. geek 6:13 pm 10/25/2012

    @ Bill: The mere fact that you ask that question betrays the fact that you are trolling for your own amusement. Please leave now before I call David Marjanovich to dismantle your arguments.

    In answer to your question: On the basis of many, many fossils and anatomical similarities. I don’t know the exact number, and don’t have the time to do your homework for you.

    Link to this
  7. 7. Bird/tree/dinosaur/etc. geek 11:00 pm 10/25/2012

    One small quibble with the illustrations: microanalysis of the feathers has shown that *Microraptor* had iridescent black plumage, like a modern grackle, and that it had two slightly elongated central tail feathers. If possible, please update the illustrations.

    Link to this
  8. 8. David Marjanović 1:33 pm 10/26/2012

    I have seen the legs-over-the-tail model work plausibly, as well, though.

    Do you mean the legs splayed out to the sides? That only works if you take the thighbones out of the hip sockets, turn them, and ram them against the hip sockets in such a way that there’s no space for the muscles that would pull the legs up in the first place. Completely impossible.

    Are there any updates about its possible capabilities of powered flight?

    No; Justin Hall and Mike Habib deliberately looked only at things that would work as well in gliding as in powered flight.

    Bill: The mere fact that you ask that question betrays the fact that you are trolling for your own amusement.

    That’s not true. The fact that he’s not being sincere is only revealed by his name: he’s a creationist who has commented on Tet Zoo.

    Bill, you can easily answer your question on your own by familiarizing yourself with the animals in question. You have a lot to learn, because you’ve been sleeping through the past 30 years. Do you have the courage to go wherever the evidence will lead?

    microanalysis of the feathers has shown that *Microraptor* had iridescent black plumage

    A poster presented at the same conference has reopened the question of melanosomes vs. bacteria. The illustration by David Krentz (a digital 3D model presented in both talks) doesn’t show any colors, just the shape of the animal.

    But weren’t there feathers on the thumb…?

    Link to this
  9. 9. David Marjanović 1:37 pm 10/26/2012

    Justin Hall and Mike Habib deliberately looked only at things that would work as well in gliding as in powered flight.

    …and Mike said so in reply to Kevin Padian’s question in the questions session after his (Mike’s) talk. Ms Wong, didn’t you hear that? You were present!

    Link to this
  10. 10. Bird/tree/dinosaur/etc. geek 2:03 pm 10/26/2012

    Hey! David Marjanović! By “legs over the tail” I meant thrust backwards, as if the animal had just jumped off of a branch. The legs-to-the-sides model has been debunked too many times to be plausible to anyone but the BANDits.

    Link to this
  11. 11. Bird/tree/dinosaur/etc. geek 2:06 pm 10/26/2012

    “”"A poster presented at the same conference has reopened the question of melanosomes vs. bacteria. The illustration by David Krentz (a digital 3D model presented in both talks) doesn’t show any colors, just the shape of the animal. “”"

    Really? I hadn’t seen that. Interesting.

    On the Crofut matter: Should someone email SciAm and try to get him banned? Because he’s REALLY annoying:
    http://blogs.scientificamerican.com/observations/2012/10/05/house-science-member-says-earth-is-9000-years-old/
    Read the comments thread.

    Link to this
  12. 12. greenhome123 11:19 pm 10/26/2012

    This reminds me that I have seen chickens with feathers on their feet. Maybe it will one day be possible genetically engineer a creature similar to a Microraptor to see how it flys. I wish we could obtain viable DNA from dinosaurs, but I recently heard that DNA half life is only about 500 years, so unfortunately it probably won’t be possible. Nevertheless, the ancestors of these dinosaurs are alive today as birds, so maybe it is possible to find answers to these questions by looking into their DNA. Viva La Evolucion

    Link to this
  13. 13. Bird/tree/dinosaur/etc. geek 7:47 am 10/27/2012

    @ greenhome: No, it wouldn’t work. *Microraptor* was an evolutionary “dead end”, leaving no extant descendants.

    Link to this
  14. 14. Bill_Crofut 12:05 pm 10/27/2012

    Dr. Marjanović,

    Sleeping through the past 30 years is an accusation that’s untrue. The truth is, wading through the professional literature for the past 30 years has produced no better answer to my question than what has been posted here.

    Test my courage to go wherever the evidence will lead. Recommend a source in the online professional literature (as long as it’s available to me at no cost) that will provide such evidence.

    Whoever “revealed” my status as a creationist is only 2 years after the fact.

    Link to this
  15. 15. Bill_Crofut 12:06 pm 10/27/2012

    Bird/tree/dinosaur/etc. geek,

    For the upteenth time, the author of this web page has the authority to ban me from commenting just as has been done by four others.

    Link to this
  16. 16. Bird/tree/dinosaur/etc. geek 3:02 pm 10/27/2012

    Four others, Bill? I’m impressed. It takes real trolling skill to be banned that many times.

    Personal advice, because I pity you and admire your faux politeness: don’t anger David Marjanović. He enjoys playing Creationist Pong even more than I do, and he’s more factually punctilious than Huxely. Don’t make him mad.

    Link to this
  17. 17. David Marjanović 8:15 pm 10/29/2012

    By “legs over the tail” I meant thrust backwards, as if the animal had just jumped off of a branch.

    Oh, that wouldn’t put them over the tail. There’s no way to make the thighs horizontal, or to extend the knees to 180°.

    DNA half life is only about 500 years

    I’ve heard it lasts 100,000 years under good conditions; under the ice of Greenland 2.5 million years at the least. However, no place has stayed frozed for the last 66 million years – except perhaps the Gamburtsev Mountains in Antarctica, and they’re covered by a mile of ice.

    Sleeping through the past 30 years is an accusation that’s untrue. The truth is, wading through the professional literature for the past 30 years has produced no better answer to my question than what has been posted here.

    I have to say, if you’ve been reading primary literature on the topics you talk about for the past 30 years, you’ve been hiding that really, really, really well. You don’t sound as if you had ever been to a university library (in meatspace or via institutional online access to scientific journals).

    the online professional literature (as long as it’s available to me at no cost)

    See? Most of it isn’t available at no cost. (Unless, that is, you write to the authors and ask them for a pdf.)

    I recommend you take any phylogenetic analysis of theropod dinosaurs and study it. There are dozens. To understand them, you’ll need to learn basic skeletal anatomy first, though.

    He enjoys playing Creationist Pong even more than I do

    I don’t really enjoy it. I have SIWOTI syndrome.

    and he’s more factually punctilious than Huxely.

    …Seeing as I’ve never read almost anything by Huxley, I can’t judge that… :-]

    Link to this
  18. 18. David Marjanović 10:47 pm 10/29/2012

    I’ve now replied on the other thread. Turns out Bill_Crofut is a geocentrist and either refuses to learn from his experience at Tet Zoo or ran away from there too early and didn’t see the replies to the nonsense he dumped. He’s one of those people who somehow manage to believe that all science was done decades ago, then all the scientists retired, and the publishers have mindlessly reprinted the textbooks unchanged ever since.

    Link to this
  19. 19. Bill_Crofut 9:05 am 10/30/2012

    Bird/tree/dinosaur/etc. geek,

    Thank you for complimenting me on my “trolling skills” (whatever that means).

    It’s not my intention to make anyone “mad” (angry?). My purpose is to point up, what for me, are the inadequacies of the evolutionary paradigm as an explanation for biological reality.

    Link to this
  20. 20. David Marjanović 5:50 pm 10/30/2012

    My purpose is to point up, what for me, are the inadequacies of the evolutionary paradigm as an explanation for biological reality.

    Too bad, then, that you’ve invested so little effort in trying to find out whether they really are inadequacies.

    Link to this
  21. 21. Bill_Crofut 1:32 pm 10/31/2012

    Dr. Marjanović,

    “Darwin himself considered that the idea of evolution is unsatisfactory unless its mechanism can be explained. I agree, but since no one has explained to my satisfaction how evolution could happen I do not feel impelled to say that it has happened. I prefer to say that on this matter our information is inadequate.”

    [W. R. Thompson. 1956. Introduction. In: Charles Darwin. Origin of Species. Everyman Library No. 811. London: J. M. Dent and Sons. Reprinted with permission. Evolution Protest Movement. 1967. NEW CHALLENGING ‘INTRODUCTION' TO THE ORIGIN OF SPECIES. Selsey, Sussex: Selsey Press Ltd., p. 12]

    Link to this
  22. 22. Bird/tree/dinosaur/etc. geek 9:35 pm 10/31/2012

    Bill, you need to get a life. You and your heckling of important scientists like David Marjanović are pathetic.

    David, I’m sorry for not being precise enough (I forgot that I’m talking to the PrecisionMan! :) ). I meant that the Nova (I think) episode showed that efficient gliding was possible if the legs were held back so that the leg feathers and the tail feathers overlapped.

    “”"SIWOTI syndrome”"”

    Try therapy, or having a hurricane knock out your power and Internet for a few days. Then again, it hasn’t worked for me! :)

    “”"See? Most of it isn’t available at no cost. (Unless, that is, you write to the authors and ask them for a pdf.)”"”

    I LOATHE paywalls, mostly because they help cause people like Bill.

    “”"I recommend you take any phylogenetic analysis of theropod dinosaurs and study it. There are dozens. To understand them, you’ll need to learn basic skeletal anatomy first, though.”"”

    But he won’t. He’ll just look at the fossils and say that they look like chicken bones, or that God put them there as a prank (if he sees them in situ).

    Link to this
  23. 23. Bill_Crofut 12:18 pm 11/1/2012

    Bird/tree/dinosaur/etc. geek,

    Re: “But he won’t. He’ll just look at the fossils and say that they look like chicken bones, or that God put them there as a prank (if he sees them in situ)”

    You don’t know that until you try; until then, you’re simply engaging in speculation.

    Link to this
  24. 24. Bird/tree/dinosaur/etc. geek 1:15 pm 11/1/2012

    “”"You don’t know that until you try; until then, you’re simply engaging in speculation.”"”

    Then go look at some theropod fossils, and provide me with some data.

    Link to this
  25. 25. Bill_Crofut 10:31 am 11/2/2012

    Bird/tree/dinosaur/etc. geek,

    Re: “Then go look at some theropod fossils, and provide me with some data.”

    Ok:

    https://www.google.com/search?q=theropod+fossils&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=SdiTUMreJeHo0gHssIDoAQ&ved=0CCwQsAQ&biw=1440&bih=799

    Now what?

    Link to this
  26. 26. Bird/tree/dinosaur/etc. geek 1:39 pm 11/2/2012

    @ Bill: And you conclude what? Also, please look at actual fossils, not just pictures.

    Link to this
  27. 27. Bill_Crofut 12:02 pm 11/3/2012

    Bird/tree/dinosaur/etc. geek,

    My conclusion, implied in comment 5, is that the evolution of birds from reptiles has not been established. As regards looking at real fossils, let me share an observation from the late Prof. Stephen Jay Gould:

    “As a paleontologist and evolutionary biologist, my trade is the reconstruction of history….Scientists who study history, particularly an ancient and unobservable history not recorded in human or geological chronicles, must use the inferential rather than experimental methods.”

    [1978. Senseless Signs of History. NATURAL HISTORY, October, p. 22]

    Link to this
  28. 28. Bird/tree/dinosaur/etc. geek 12:38 pm 11/3/2012

    @ Bill:

    “”"My conclusion, implied in comment 5, is that the evolution of birds from reptiles has not been established. “”"

    Then you are 50 years behind current scientific thought.

    “”"As regards looking at real fossils, let me share an observation from the late Prof. Stephen Jay Gould:

    “As a paleontologist and evolutionary biologist, my trade is the reconstruction of history….Scientists who study history, particularly an ancient and unobservable history not recorded in human or geological chronicles, must use the inferential rather than experimental methods.””"”

    Your point being?

    You lost the respectability and qualifications to criticize scientific theories when you proclaimed yourself to be a creationist and geocentrist. Please leave now.

    Link to this
  29. 29. Bill_Crofut 12:53 pm 11/5/2012

    Bird/tree/dinosaur/etc. geek,

    Scientific thought is not scientific evidence.

    My point is really not my point at all; it’s Prof. Gould’s point. If you don’t understand his point then, it seems to me, you need to take some of your own advice.

    Re: “You lost the respectability and qualifications to criticize scientific theories…”

    It was never my claim to be qualified to criticize scientific theories. That’s the reason for quoting those in the scientific literature who are qualified. However, you then refer to me as a quote miner (whatever that means). You have put me in a no-win position; sniff, sniff.

    Link to this
  30. 30. Bird/tree/dinosaur/etc. geek 1:16 pm 11/5/2012

    @ Bill:
    “”"Scientific thought is not scientific evidence.”"”

    No, a theory has enough evidence to back it up that it is accepted as fact. A theory is specific and must have a mechanism by which it can be disproven by new evidence. See the Precambrian rabbit thought experiment.

    “”"My point is really not my point at all; it’s Prof. Gould’s point. If you don’t understand his point then, it seems to me, you need to take some of your own advice.”"”

    And you DELIBERATELY misunderstood Gould’s point. I can’t reason with you.

    “”"Re: “You lost the respectability and qualifications to criticize scientific theories…””"”

    Actually, you never were qualified.

    “”"It was never my claim to be qualified to criticize scientific theories. “”"

    Could have fooled me.

    “”"That’s the reason for quoting those in the scientific literature who are qualified. However, you then refer to me as a quote miner (whatever that means). “”"

    Look it up. Wikipedia is your friend.

    “”"You have put me in a no-win position; sniff, sniff.”"”

    No, you put yourself into it by being a quote-mining creationist, geocentrist, and troll.

    Link to this
  31. 31. Bird/tree/dinosaur/etc. geek 1:21 pm 11/5/2012

    In short, Bill, you are completely irrational. You say that you don’t think that birds are descended from “reptiles”. Even the BANDits (pseudoscientific cranks) try to convince people that birds are descended from “reptiles”, although they tend to change which particular “reptile” to point to every week.

    Everyone accepted the massive body of evidence showing that birds are theropod dinosaurs 50-something years ago. It’s old news, Billy boy.

    Finally, your entire set of irrational beliefs is based upon a moldering old religious book that is about half ancient Israeli political propaganda and about half proto-communist teachings (Jesus is all for the little guy, and so was Karl Marx. The New Testament reads a hell of a lot like the Communist Manifesto).

    Link to this
  32. 32. Biology in Motion 4:18 pm 11/5/2012

    Great to see some discussion on Kate’s article regarding our work. As a quick note regarding the “reverse thrust” idea:

    “Hey! David Marjanović! By “legs over the tail” I meant thrust backwards, as if the animal had just jumped off of a branch.”

    All launching animals, be it obligate un-powered flyers or powered ones, initiate flight using a leap of some kind from the substrate (which, for arboreal animals, may be a branch). In a prior model presented by Xu Xing and colleagues (but not formally published), the legs were kept “swept back” to provide some weight support with inverted wings. There are possible joint excursion problems with this model, but there is also the issue that the rachis of the hindlimb feathers would then be on the wrong side of the feather (about a 1/4 chord from the trailing edge, instead of the leading edge), which is rather dubious. There are also potential instability problems with this model. It does, however, stand as much better than the sprawling models.

    Link to this
  33. 33. Bird/tree/dinosaur/etc. geek 4:28 pm 11/5/2012

    @ Biology in motion:
    Oh. I only saw it on NOVA. I haven’t actually had the chance to read the paper yet.

    Link to this
  34. 34. Bill_Crofut 9:55 am 11/6/2012

    Bird/tree/dinosaur/etc. geek,

    Re: “…a moldering old religious book…”

    See comment 5:

    http://blogs.scientificamerican.com/observations/2012/10/24/fish-shoots-down-prey-with-super-powered-jet-video/?WT_mc_id=SA_DD_20121025

    Re: “The New Testament reads a hell of a lot like the Communist Manifesto.”

    Please provide a specific example.

    Link to this
  35. 35. Bird/tree/dinosaur/etc. geek 12:08 pm 11/6/2012

    Jesus is all about the little guy and communal well-being. He advocates charity, equality, and generosity. That’s socialism right there.

    Why the link? It makes no sense.

    Link to this
  36. 36. Bill_Crofut 11:36 am 11/7/2012

    Bird/tree/dinosaur/etc. geek,

    Re: “That’s socialism right there.”

    DIVINI REDEMPTORIS

    ENCYCLICAL OF POPE PIUS XI ON ATHEISTIC COMMUNISM MARCH 19, 1937

    http://www.papalencyclicals.net/Pius11/P11DIVIN.HTM

    Re: “It makes no sense.”

    Why should that surprise you?

    Link to this
  37. 37. Bird/tree/dinosaur/etc. geek 12:10 pm 11/7/2012

    No, I meant that the link that you provided had nothing to do with this topic, Bill. Perhaps I could have worded that statement better, though.

    Also, wasn’t Pius the Eleventh the guy who covered up for Hitler?

    Link to this
  38. 38. Bill_Crofut 11:28 am 11/8/2012

    Bird/tree/dinosaur/etc. geek,

    Re: “…the link that you provided had nothing to do with this topic…”

    That is correct; it only had to do with your comment, ” “…a moldering old religious book…”

    No pope covered up for Hitler. Pope Pius XII has been unjustly accused of having done so. However, after WWII, he was praised in the public media by such well-known personalities as Prof. Albert Einstein and Israli Premier Golda Mier for his efforts to aid the Jewish people during the war.

    Pope Pius XI also promulgated an encyclical condemning Nazism:

    [MIT BRENNENDER SORGE, ON THE CHURCH AND THE GERMAN REICH MARCH 14, 1937, http://www.papalencyclicals.net/Pius11/P11BRENN.HTM

    The prevailing wisdom is, the encyclical was actually written by Eugenio Pacelli, then Cardinal Secretary of State who, upon his election to the papacy in 1939, took the name Pius XII.

    Link to this
  39. 39. Bird/tree/dinosaur/etc. geek 7:33 am 11/9/2012

    OK, Billy Boy. I don’t see how my comment about your moldering old religious book has any bearing on this discussion, though. Unlike you, I regard everything, even my own eyes, as possibly fallible, and use rigorous methods of proof and disproof as often as possible.

    What I’ve been saying about Jesus? He probably would have hated people like you. Historical evidence shows that he cared deeply about individual rights, equality, and peace. You evangelicals want to crush individual rights (i.e. abortion rights), eliminate equality (I recently heard an evangelical say that non-Caucasian people should be rounded up and shipped off to Africa where they can be heathen Methodists in their own private hell), and care nothing for peace (many warmongering neocons are also evangelicals). In light of this, you have two options to avoid utter hypocrisy: becoming a Muslim (but Islam has fundies, too), or starting your own religion of conservatism(you probably won’t get taken seriously, though, and it could become a cult very quickly).

    Link to this
  40. 40. Bill_Crofut 10:53 am 11/9/2012

    Bird/tree/dinosaur/etc. geek,

    Thank you for setting me on the right path even though the label “evangelical” does not apply to me (ask any evangelical).

    Link to this
  41. 41. Bird/tree/dinosaur/etc. geek 4:20 pm 11/9/2012

    Billy:
    Catholic fundamentalist, Protestant fundamentalist, Muslim fundamentalist; they’re all equally evil. Bin Laden, Terry Jones, etcetera. Fill in the blanks.

    Link to this

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