Pterosaurs couldn’t fly? Japanese scientist comes out swinging.

What on earth am I supposed to do with this thing?: A pterosaur considers his situation.
What on earth am I supposed to do with this thing?: A pterosaur considers his situation.Courtesy John Conway
Paleontology, y’all, paleontology. We’ve got these bones, these fossilized bones. And they’re nice bones, don’t get me wrong, but sometimes they leave a little to be desired when it comes to reconstructing the nitty gritty and sticky details of what living dinosaurs (and pterosaurs, ichthyosaurs, mosasaurs, therapsids, etc) were actually like. A skeleton can give us a good idea of a creature’s general shape; it can show where the muscles went (more or less), what sort of food it ate, how it probably moved—that kind of thing. But how did they behave? What color were they? Exactly how strong were they? There are a whole slew of questions that get to be a little tricky.

So, how do paleontologists go about answering these questions? They get creative, they study all the tiniest details of the fossils, and, sometimes, they look to living animals for analogy—that is to say, if an animal alive today that lives in a similar environment to that of an extinct animal, and has a similar body type to the extinct animal, you might be able to base knowledge of the extinct animal on what you know of the living animal.

It’s a valuable avenue of study, but dinosaurs and their ilk were pretty different, after all, so how far do you think can we take analogies to living creatures?

And now on to the news item.

A Japanese researcher has opened up his sass-box and gotten all up in the faces of paleontologists around the world. Pterosaur specialist paleontologists are particularly fired up, and they’re a dangerous bunch. “Peer review” among pterosaur specialists, as I understand it, involves switchblades, and the majority of the community sports eye-patches.

This scientist, Katsufumi Sato of the University of Tokyo, is saying that pterosaurs (all of the huge extinct flying reptiles) probably maybe couldn’t actually, you know… fly.

Oh no you di’en’t!

Says Sato: Yes, yes I did. Specifically, what the scientist did was place accelerometers on the wings of a couple dozen sea birds on the Crozet Islands. The accelerometers measured, more or less, the flapping force and speed of the birds’ wings.

Among the birds studied were wandering albatrosses, which have the largest wingspans of any living birds. Large seabirds like this have often been used as analogies for pterosaurs for their somewhat similar body shapes. Many pterosaurs probably lived in a similar habitat to modern seabirds as well.

Albatrosses fly by riding shifting wind currents, and by flapping their wings when the wind isn’t suitable, or is absent entirely. Sato found that the seabirds he studied have two flapping speeds, a faster speed for taking off, and a slower speed for staying aloft in the absence of wind. He also noticed that, as this flapping speed is limited by the birds’ strength, it decreases in heavier birds with longer wings.

According to the calculations Sato based off of this data, birds (or pterosaurs) weighing more than about 90 pounds would be unable to fly without using wind currents—they simply wouldn’t be able to flap their wings fast enough to stay in the air. There were certainly pterosaurs that size and much smaller, but a lot of flying reptiles were probably a great deal larger than that (a very conservative estimate for the quetzalcoatlus, for example, would have it weighing around 220 pounds).

The article I read on this research doesn’t get into Sato’s hypothesis much more than that, but I’d assume that this means that larger pterosaurs would then also be unable to take off from anywhere other than, say, a cliff face. I wonder if the implication is also that they wouldn’t be doing any flying at all; that medium to large pterosaurs wouldn’t even be gliding on wind currents because, at some point, they’d need to gain some altitude on their own steam.

But, whatever the specifics, them’s fightin’ words, and pterosaur specialists the world over are no doubt sharpening their boot-spikes, and wrapping their fists in chains.

Is it a valid analogy? Maaaaybeeee… But I’m betting against it. There have been some interesting theories lately about how the largest of the pterosaurs may not have flown as much as we used to think, but they don’t imply that they couldn’t fly at all. In fact, the study I’m thinking of would further distance pterosaurs from large seabirds in terms of behavior and their ecological niches (making any analogies a little less apt).

Other scientists argue that in addition to anatomical and physiological differences that should be considered, the atmosphere of the Mesozoic was, on the whole, somewhat denser, and had higher concentrations of oxygen—factors that would have allowed flight for larger, heavier animals. Actually, I recommend checking out the discussion following the article. There are a bunch of explanations of how pterosaurs could have flown, despite what this study suggests. But, if you do go, bring your knives—they’re an angry bunch.

Your Comments, Thoughts, Questions, Ideas

Liza's picture
Liza says:

And if you're here at the Science Museum of Minnesota, go stand in the lobby and take a gander at the Quetzalcoatlus hanging from the ceiling and try to imagine that sucker actually taking off.

posted on Fri, 10/03/2008 - 1:41pm
bryan kennedy's picture

On some level it seems hard to imagine the process of evolution favoring these animals growing bigger and more flight focused without the ability of flight. I mean many of the flightless birds today don't exactly look like giant soaring wings, whereas it's hard to image the Quetzalcoatlus doing anything BUT flying. It's no ostrich.

posted on Thu, 10/23/2008 - 2:05pm
JGordon's picture
JGordon says:

That's kind of what I thought. Big pterosaurs were around for millions and millions of years, so they obviously had time to continue to evolve, but why would they keep those huge wings?

Even if you buy this theory, that pterosaurs walked around like giraffes (and the authors aren't proposing that that's all they did), it doesn't make sense that they wouldn't have lost that big, folded-back flight finger.

I feel like something is missing from the press on this research.

posted on Thu, 10/23/2008 - 3:14pm
JGordon's picture
JGordon says:

Mark Witton, the paleontologist behind the walking-pterosaur theory (linked to above), had this to say about Sato's research in the comments of his flickr photostream:

I was involved with a very similar discussion over at Tetrapod Zoology: the general concensus appears to be that it's a bit bogus. Here's what I said:

"Funny how Sato et al's work should be discussed in the same thread as another work of fiction (boom tish!) [erm, you may need to see the original post to get that]. New Scientist spoke to me about Soto's work a few weeks back and I was amazed to hear the results of his study: it really seems to lack any common sense at all. I mean, seriously, has he seen the size of the biggest azhdarchids? There's simply no way in Hell that they weighed 40 kg. I estimated a burly Pteranodon at something like 30 - 35 kg, and that's lighter than you would expect for a 6 - 7 m pterosaur. 40 kg is nothing, man: eight year-old kids weight 40 kg. Eight year olds. The length of the Quetzalcoatlus humerus is almost half-as-long as an eight year old. Why, dear God, why, don't people think about what they're saying before they run to the likes of New Scientist? Maybe Soto has the maximum weight of an animal that flies in a specifically albatross manner, but he's barking up the wrong tree with other flying animals.


You can see the original comments on the Tet Zoo blog post here. Bottom line: you can't take a 12 m span pterosaur and package it into 40 kg (actually, the original article says 52 kg - also note that the work all this is based on was not peer-reviewed by other scientists before publication). Sato et al may have discovered something about the maximum size of an albatross-like flier, but I suspect they're barking up the wrong tree about other flying animals.

I recommend checking out Mark's flickr account if you're into paleontology—he's got some interesting stuff to say there, and some pretty cool paleo-illustrations.

posted on Mon, 11/10/2008 - 10:43am
Anonymous's picture
Anonymous says:

If quetzacoatlus happened to be light gray, gray, dark gray,and black, that will be soo aawwssoommee!!!!!!!

posted on Tue, 07/14/2009 - 12:11pm
JGordon's picture
JGordon says:

I don't know about all those "o"s but that could be.

A lot of birds are light on their undersides so they blend in with the sky more (to hide them from their prey), and dark on top (to hide them from predators), so maybe that was the case with quetzalcoatlus too.

I'm not sure what sort of predators something the size of quetzalcoatlus would have had, though, at least in the air. And if you agree with the theory linked to above that says they spent some of their time browsing on the ground, I bet that would mean that they'd have an entirely different coloring scheme. Maybe it would be striped, speckled or spotted to blend in with trees or tall grass. (Except that grass didn't evolve until the end of the Cretaceous.)

posted on Tue, 07/14/2009 - 1:59pm
David Esker's picture

I have corresponded with both Katsufumi Sato and Mark Witton in regards to the flying ability of the largest pterosaurs. Katsufumi Sato is a behavioral ecologist who for decades has been attaching bio-loggers to mostly marine animals so as to get factual data to achieve real scientific understanding. Sharply contrast in terms of scientific credibility, Mark Witton is a paleontology graduate student who is the new ‘fall guy’ for the paleontology community that has been unsuccessful in explaining how the large pterosaurs flew. Mark follows in the footsteps of many senior paleontologists in that he has no understanding of either physics or aerodynamics and yet that does not stop him from pretending that he is an expert on these topics.

There are two primary reasons why larger pterosaurs could not have flown in today’s atmospheric environment: 1) the power required for flight increases rapidly with weight and 2) pterosaurs were cold blooded reptiles and thus their power output is much less than that of mammals and birds. The consequence of the first factor is that the largest birds have a more difficult time achieving flight than the smallest birds and ultimately there is a limit to how large a bird can be and still be able to fly. Regarding the second factor, birds have a higher metabolism (more power) than mammals and so the largest flying bird is much larger than the largest flying bat; while none of the low powered reptiles, no matter how small, is able to fly in today’s atmosphere. Yet during the Mesozoic era the pterosaurs grew to be the largest flying animals that ever existed.

When we study the aerodynamic equations regarding the power needed for flight we recognize that the only way to reconcile the paradox of large flying pterosaurs is to hypothesize that during the Mesozoic the atmosphere was extremely thick.

A deeper understanding of the explanation given here is found at my website Dinosaurtheory.com.

David Esker

posted on Thu, 09/17/2009 - 10:21pm
JGordon's picture
JGordon says:

Hi, Mr. Esker

Thanks for sharing your perspective. Pretty interesting!

You know, I read your correspondence with Mark Witton in the comments section of his flickr page. It's too bad—it looks to me like there was some miscommunication early on, and then things got a little too sarcastic and argue-y for anybody to learn anything.

This wasn't very nice:

I thought more of you earlier. But now I see another poorly educated paleontologist that does not understand the science concepts or the math. I could help you understand the aerodynamics. I would like to help you. But my guess is that you fall in with the other paleontologists in being to arrogant to ask for help.

But, then again, this was pretty sassy too:

No doubt I'll be accused of slinking away from the light of the 'Esker Revolution' to hide behind my own pride, arrogance or colleagues, but, in all honesty, I think my time is better spent finishing my PhD than discussing this with you at the minute.

Turns out you guys are both real scientists after all!

I expect this is the sort of thing that might require physicists, behavioral ecologists, and paleontologists working together to really understand. Next year, right?

With regards to your "dinosaur paradox"—that is really interesting. But it's difficult for me to imagine "that the Earth’s air could be so thick that its density would be comparable to water." Or is that hyperbole? And I'll say now that I'm not a physicist or a paleontologist, but... I know the mesozoic was a strange place, but it's not like the things living there were utterly unrecognizable. I feel like anything evolving for 150 million years in those conditions would be considerably more... ichthyoform (I might have made that word up... more like a fish, anyway). You say that some dinosaurs evolved to "swim" through this thick atmosphere, but what about... I don't know... everything else? Interesting, though.

posted on Fri, 09/18/2009 - 10:16am
bryan kennedy's picture

I can't decide if all the sarcasm you call out here is funny or annoying. Comments on a blog are such a crummy way to follow a conversation, because so much is lost in the tone of people's speech. Alas, this is the reality of people debating these issues out in this medium I guess.

posted on Fri, 09/18/2009 - 3:22pm
JGordon's picture
JGordon says:

I think it's a little annoying, although I'm certainly guilty of it too. (Because I, ah, also think it's funny.) It's unfortunate, because it's such a cool, quick way of sharing information (I mean, this is Science Buzz, after all), but the medium is perfect for for endless last-words and passive aggressive snarkiness that would never fly in a face to face conversation. I mean, can you imagine saying either of the above quoted comments to someone in person?

I have the feeling that the pre-internet nature of scientific debate wasn't necessarily a great starting point, either. I remember doing research in school, reading back and forth publications in journals, and realizing that a big portion of what was being said was just the scientists being pissy at each other. It was sort of a depressing revelation.

I should say, though, that I have also corresponded with Mark Witton a little in the past, and I found him to be really helpful and insightful. The same can probably be said about Mr. Esker.

Anyways... it's just a funny thing.

posted on Fri, 09/18/2009 - 4:49pm
David Esker's picture
David Esker says:

I enjoyed your balanced and humorous critique of my disagreement with Mark. I am not sure if I was right or wrong in telling Mark that he does not have the math and physics education necessary to understand the paradox of flying pterosaurs. On the one side, science can not move forward until we properly identify the problems; while on the other side, my bluntness possibly served no purposed other than to hurt his feelings.

Changing topics, Dr Sato’s presentation of his research and the emotional reaction of the paleontologists is a classic example of the actual way that science awkwardly moves forward. While those who write science history might want us to believe that every new successful scientific hypothesis was respectfully discussed by rational scientists before they cheerful embracing its merits, rarely if ever has this been true. What actually happens is that because new ideas overturn old beliefs nearly every new good scientific idea has usually been met with strong resistance that is more emotional than rational. Scientists are people and people do not like to be informed that their beliefs are wrong.

A couple of your comments regarding my Thick Atmosphere Solution were interesting:

1) ….it is difficult for me to imagine…

We teach young science students that science requires imagination yet when the moment arrives for us it becomes ‘do as I say not as I do’. The difficulty in imagining a possibility is not a factor in determining if a hypothesis is correct or not. Therefore, it occasionally it pays to listen to the ideas of youthful scientists; since our ability to imagine possibilities that lie outside-the-box decreases with age, we may not be aware of solutions to problems that we are attempting to solve.

2) …but what about…I don’t know…everything else?

This is another one of these ‘do as I say not as I do’ things.

A qualification determining if a hypothesis is a legitimate scientific hypothesis is whether the hypothesis makes predictions that can be tested such that there is a possibility of it being proven wrong. Again after teaching this idea to young science students the science community goes off and does whatever it wants. As a result there are numerous examples of beliefs held by scientists that should not be considered scientific beliefs because these beliefs do not allow the possibility of being proven wrong. In addition, many more examples can be given of beliefs that have been proven wrong and yet the science community rejects the verdict rather than abandoning their incorrect beliefs.

In regards to your “everything else?” the Thick Atmosphere Solution is clearly a scientific hypothesis in that it makes a lot of predictions that can be tested. The Thick Atmosphere Solution makes major predictions in the science disciplines of paleontology, geology, planetary science, and biology. With so many tests that it must pass it is easy to jump to the assumption that there is no possibility that it can succeed. Yet the Thick Atmosphere Solution is succeeding. Tens of thousands of scientists have now read the explanation of the Thick Atmosphere Solution, they have become irritated that theirs beliefs are being questioned, and yet they have failed to come up with a counter argument as to why the Thick Atmosphere Solution should not be accepted.

In the same way that Dr. Sato’s research does not make the paleontologists happy, the Thick Atmosphere Solution likewise questions old beliefs and so it is unpopular as well. Yet the scientific truth is not determined by politics but rather it is the conclusion of sound arguments based on the physical evidence. Scientists may not like these conclusions but if they wish to have credibility as scientists they need to have their rational side overrule their emotions. Instead of denying such obvious paradoxes as gigantic flying reptiles, the paleontologists and other affected science disciplines need to pull their heads out of the sand so as to demonstrate that they are capable of rationally discussing exciting new scientific ideas.

David Esker

posted on Sat, 09/19/2009 - 12:52pm

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