Pterosaurs couldn't soar, says expert

Bumblebees have been proven to be incapable of flight as well (in the way that birds fly). There are other ways to fly.

I read a book a while back (I think it was called 'Oxygen', but I wouldn't put money on it) which discussed hypothetical changes in the atmosphere of the Earth over the various epochs. One of the author's ideas was that the era of giant dragonflies with wingspans over a meter, and the eras of various pterosaurs would have required a much higher partial pressure of oxygen (given that insects absorb oxygen through spiracules (sp?)) and a significantly higher absolute atmospheric pressure to allow these animals to fly at all. The point being that it is possibly a mistke to assume that our current atmosphere is some kind of "standard".

Beyond the last sentence of the article, I wonder if Sato has taken this possibility into account.

I doubt he's gotten that far D666. He simply stated that they wouldn't be able to fly in "standard" conditions, ie, those that exist today. As you correctly point out the conditions in the past were not identical.

I haven't read anything about atmospheric pressure in the past, but I do remember reading that the oxygen content in the atmosphere *had* to have been higher, or else those large insects simply could not have existed. (They wouldn't have been able to breathe, never mind fly. Insects use a very different breathing mechanism than we do. On small scales it is very efficient, but it quickly (geometrically in relation to size increases) becomes useless. That's why we don't have large insects on Earth. They can't breathe above a certain size.)

I wonder if Sato has ever seen a hang-glider. Weighs over 100kg, yet can manages to stay aloft indefinately without flapping any wings.

ALL the researchers miss what I have been pointing out for 30 years; atmospheric pressure HAD to be MUCH higher in the past than it is today. In the carboniferous, ~240E6 yrs ago, the insects were very large,e.g. 2.5 foot dragonflys. The only way insects could get enough oxygen to diffuse into their bodies was if the partial pressure of O2 was MUCH high then. This would be true if the concentration of oxygen was much higher than today (along w/ MUCH higher CO2 levels because photosynthesis stops working at 27% O2 and 400 ppm CO2 at 1 atmos.) OR the total atmospheric pressure was MUCH higher. possibly BOTH.

The tuatara (100E6 yr old reptile)lives on the edge of oxygen deficit all the time. When it evolved that certainly could not have been the case so the above also applies. The dragonfly mentioned above and other flying insects would have had a much a higher wing loading than today because the weight increases w/ the cube of size whereas the wing area to the square so the above applies again.

"Pterosaurs couldn't soar" nor could they launch themselves off the ground at todays 14.7 psi atmospheric pressure. They ONLY explanation is much higher atmospheric pressure.

Consider this, if dinosaurs had a blood chemistry similar to the tuatara, i.e. not very good under present day conditions, and at the time of their mass extinction 65E6 yrs ago there was a drastic reduction in air pressure and/or O2 concentration, i.e partial pressure of O2, then that would explain a lot about why they disappeared. They asphyxiated.

Flawed research. He did not account for the high oxygen content of the air in dinosaur epoch. The planet was literally covered with forrests. The high O2 content enabled supersized insects to exist. They rely primarily on diffusion for gaseous exchange and therefore only high O2 concentrations make large insects viable. It is inconsistent to base dinosaur physiology on contemporary animals.
In addition i would use a giant fruit bat as a model instead of a bird.
That pterosaur must have been an impressively ugly animal.

There is obviously flawed logic in the conclusion that Pterosaurs "couldn't fly." It's much equivalent to ridiculously predicting the development of fins on terrestrial animals as precursive to a future aquatic taxon - presumably wings will only reach functional maturity in long-term operational entanglement with the mechanics of their environment that "select" for their fuller development and the evolutionary fitness of that taxon. I suggest that it should even be possible to retro-calculate necessary characteristics of a Jurassic atmosphere by considering its minimum required lift, drag and effective aerodynamic "bouyancy" effects on the typical Pterosaur morphology. Such an exploration would be far more interesting than concluding that "wings can't fly."

OK... The atmosphere was different. So what WERE the exact conditions of the atmosphere back then? Then Sato's benchmark can be adjusted. Also, what were the muscle sizes of the pterosaurs.

Besides, when I was growing up they told us that pterosaurs just glided like flying squirrels. In this sense they are not using their muscles to flap but just to control glide direction.

Actually, the argument that giant insects needed higher concentrations of atmospheric oxygen isn't necessarily correct. It has recently been discovered that the "breathing tubes" in the bodies of some large insects are actually not as stiff as previously thought. They are actually flexible enough that these insects can "breath" by expanding and contracting the tubes, which results in a MUCH higher oxygen absorption rate than is possible with just "passive" diffusion (as is the case with smaller insects).

Therefore, it may be the case that atmospheric oxygen concentrations weren't that different in the time of these insects than now. Assuming significantly higher oxygen concentrations has a lot of problems, such as the drastic increase in flammability of vegetation.

The question I have is - why did the pterosaurs evolve wings if they could not fly???

One problem is the article's source: AFP. It doesn't describe the nature of Sato's "controversial" conclusions, except to say 44 pound birds under his experimental conditions can't fly. The rest of the article is not used to support the controversial headline conclusion -- most of it's about other things.

The AFP reporter probably got a bonus for their great work: Sensationalizing conclusions so that they fit conveniently on a Yahoo! Web page and in a 30 second slot in the evening news. They're trying to run a business, not report science accurately. No footnotes, no citations. None of that garbage. Don't need it.

DoctorKnowledge,

How dare you question the competency and accuracy of our beloved media! If they say that there is proof that pterosaurs could not fly then you have the obligation to suck it up and get with the program. It is suddenly obvious that pterosaurs flopped around on the ground and anyone who would question that is on par with creationists and holocaust deniers - reality challenged heretic!

For shame DoctorKnowledge, for shame!

People, just because the scientists say one thing and the media claims they say something different does not mean that the media are not your rightful overlords.

Actually after a little research I found that oxygen levels were very low during the time this creature was alive. It was actually the periods just before it that had phenomenal oxygen levels (Carboniferous to very early Triassic).

However this says nothing about atmospheric pressure, which of course would have made a difference too.

If you look at the bone structure of the pterosaur it appears more similar to that of a bat.
http://visual.mer...-bat.php

Note the lack of large breast bones in both cases. Whereas birds have well developed breasts (chuckle).

Neat discussion.

For those of you who brought up hang-gliding, keep in mind that pterosaurs didn't have convenient access to SUV transport back to higher ground when the wind failed them. Hardly an adaptive trait.

It's also worth pointing out that bumblebees use a radically different mode of flight from birds because their BODIES are radically different. Pterosaurs are a whole lot more like birds or bats than they are like bumblebees.

The O2 partial pressure argument makes sense. A higher overall air pressure would probably also help, although I'm not sure if the paleo record supports that.

Velikovsky (see http://en.wikiped...likovsky ) would suggest that the existence of animals like pterosaurs and meter-wide dragonflies serves as evidence that Earth's gravity was significantly weaker in the deep past. That's an unorthodox view, to be sure, but one that the academic community has never taken seriously enough to refute convincingly.

Finally, there's behavior... lots of animals only go out when conditions are favorable, and I can certainly envision a pterosaur hanging out on his crag and conserving energy for those extra-windy hunting days.

Gravity changing is not an option as evidence is to the contrary. e.g. If such a cataclismic gravity change happened then how could the moon be locked in synchronous orbit about the earth. This implies an astronomically stable gravitational past.
There is evidence for higher O2 content. The atmospheric pressure would have to be different as a result of the change in gas composition and densities. Although the pressure change IMHO would have been negligible.

because of the constraints of RUBISCO chemistry, photosynthesis can only take place within a range of O2 and CO2 concentrations. To much O2/CO2 then mostly photorespiration and plants die. To much CO2 then there are pH problems in the plant and they die. So THE major difference then and now has to be MUCH higher atmospheric pressure then. What is important to animals is O2 partial pressure and to plants the ratio of O2 to CO2. Some of you may remember the Apollo fire in 100% oxygen at only 6 (I think) psi pressure which is a partial pressure of O2 twice found in the atmosphere.

Also, lower gravity = lower atmospheric pressure at a given temperature. So if Earth had lower gravity it would also have had less atmosphere, leading to exactly the same problem with flight as before.

A simple question, if the Pterosaurs does not fly, how come it has a very large set of wings? As we know, nature does not waste anything. So it must be using these wings to fly!!!

billydude: Nature doesn't waste anything? Say that to your appendix, which is suppose to allow you to extract additional calories from hard-to-digest plant matter (like tree leaves, grasses, etc). It doesn't work anymore in us, but we have it. And so do lions, despite the fact that they haven't had an ancestor that ate plants for a looooong long time.

Why do all these animals (and us) have useless appendixes? Cause when an animal was born without an appendix it had no advantage over those who had one. It didn't have a greater chance of survival, so it didn't thrive (at least, no more than others did).

Same reason we have useless pinky toes, and the same reason we have wisdom teeth.

There is lots of waste everywhere, if you want to see it that way or alternatively ,life is created perfectly.

The function of the appendix is not fully understood, there are theories that suggest it was usefull for primates to digest leaves,as a tool to build up resistanse to diseases or to give a safe haven too good bacteria for our digestive system.To say its useless would be inaccurate,its not well understood yet.Same applies to pinky toes and wisdom teeth.

Inherited features that become "useless" are suppost to disappear over many generations, often they seem to get alternative functions tough.If the function gives the species more of an advantage than the energy it requires to have the function disadvantages them it is a usefull feature and will stay.

because of the constraints of RUBISCO chemistry, photosynthesis can only take place within a range of O2 and CO2 concentrations. To much O2/CO2 then mostly photorespiration and plants die. To much CO2 then there are pH problems in the plant and they die. So THE major difference then and now has to be MUCH higher atmospheric pressure then.

Anyone have data on this. I am thinking the range is broad. So this would support an increase in O2 from 20% (today) to 22%.

What is important to animals is O2 partial pressure and to plants the ratio of O2 to CO2.

I would add that CO2 level is what triggers the unconscious breathing reflex in animals not O2 level.

Some of you may remember the Apollo fire in 100% oxygen at only 6 (I think) psi pressure which is a partial pressure of O2 twice found in the atmosphere.

The Apollo 1 fire was at 16 psi (2 psi above standard atmospheric pressure) and 100% O2.

Inherited features that become "useless" are suppost to disappear over many generations, often they seem to get alternative functions tough.If the function gives the species more of an advantage than the energy it requires to have the function disadvantages them it is a usefull feature and will stay.

This is a misconception. Useless things will only disappear if the creature has a better chance of survival without them. If the useless thing has no effect on the creature, positive or negative, then the item will remain their forever, unchanging, except by random chance.

Hence pinky toes. Something that use to be useful, but no longer is. But having it won't kill you. It doesn't help, but it doesn't hurt. So it stays. Humans have quite a few different minor bits and pieces that are like this.

It is believed that the conditions prior to the world wide flood of Noah mentioned in the book of Genesis would have been similar to what has been talked about above.

Look at the elongated neck and the sunken shoulders... that is where its jet pack was worn. The aliens that brought them from a lower-g planet had to equip them since they couldn't fly here...

Pitch Black had pterosaurs and they flew! maybe that is where they came from and the reason for the mass extinction!

In all seriousness, if at 400 ppm all plants will die from photosynthesis shutting down, then we are all dead in a few decades... but I seem to recall reading evidence that CO2 levels have been radically higher than today... And I recall reading about greenhouses that have additional CO2 pumped in to levels well above today's - and the plants thrive. Temperatures well warmer than today's would add atm pressure, at the very least due to some gas no longer being dissolved in the seas. And I am sure the planet has lost a bit of atm gas that has escaped into the void of space since then.

Pinky toes aren't useless btw. The outer toe (I say that b/c birds have three) provides greater stability, especially for us high center-of-gravity bipeds. Oh and hang gliders do not stay aloft indefinitely.

The wings had to have a purpose; I doubt they were nimble and could climb trees (or cliffs) like flying squirrels. It is unlikely that we have stumbled upon some rare, freakish genetic anomalies that would have died out in one generation.

There are many conclusions we can make (and have made) through science and math that are ridiculous... 1*0=(?)10*0, no heavier-than-air flying machines (birds, bees, bats?), can't pass speed of sound (bullets, shooting stars?). They defy history and the examples given that are around us.

The only way for gravity to be less back then (as far as I know) is if fundamental properties of the universe have considerably changed in that time frame. That may help explain the observed inflation in the universe (maybe incl. dark energy and dark matter), the existence of matter beyond the visible universe, not to mention how an infinitely dense point defied gravity in the Big Bang. But this is 100 million years ago, not 12 billion, even if Argentinosaurus was from the same time period and near-unfathomably huge. Atm properties (pressure, thermals, et al.), physiology, and flight mechanics (not to mention human error and lack of knowledge) sound like simpler explanations.

As for the Bible comment, there are many belief-sets that talk of a time of giants, not just Judeo-Christian stories; I find it interesting to compare ancient stories (e.g. floods, giant creatures, dragons, quetzalcoatl) to archeological and geologic evidence. Before it gets started, lets keep religion out of this; ancient stories are fun, preachy-ness from any belief-set (including atheism) doesn't belong here. Remember: Topic=Pterosaurs

In all seriousness, if at 400 ppm all plants will ...die from photosynthesis shutting down, then we are all dead in a few decades... but I seem to recall reading evidence that CO2 levels have been radically higher than today...?

Read it again! at 27% O2 and

at 21% O2 and >150 ppmCO2 we're ok

Much to do about nothing. Just look at the human body. Numerous papers have been written about the "double full". If you are unfamiliar with this gymnastic move it is when someone runs into a roundoff, back-handspring, twisting layout (google it). Physically speaking the move is impossible. Granted the last time I read a study on it was about 8 yrs ago. Bottom line is tons of people can do it without a spring floor but physically speaking it can't be done.

Much *ado*. Much ADO about nothing.

Gravitational cataclysm could explain by relative changes of gravity when the planet increase its distance (radius of orbit) from the Sun. It could happen with Earth 65 mln. years ago. And it can explain the extinction of all giants of past, both plants and animals. And it can explain increased volcanic activity, and following global changes of climate on our planet from subtropical to modern multi zonal one.
The higher atmosphere pressure cannot be sufficient explanation for a big wings of pterosaurs and giant dragonflies.
On the contrary, in the higher pressure of atmosphere or other ambient, the animal able to have smaller wings/flippers(see marine animals like a dolphins, whales, sharks, various fishes, etc.). More, they must to have much smaller wings/flippers because in the higher pressure of ambient they need to be much more stronger (with better and durable bones and muscles) to resist to higher pressure of ambient.
All these I said in the 1997.
The bigger wings useful only in the smaller atmosphere pressure conditions. They works as sails, in this case.
The giant dragonflies could break their wings in modern atmosphere pressure and modern gravity, because flying insects must flapping their wings more quicker than birds.
For giants of the past, we have many other problems connected with their weight and sizes that cannot be explained by higher atmosphere pressure and higher O2 content.
The modern giraffe have problems with blood pressure because he have big height about 7-8 meters. Brachiosaur had about 20 meters of height!
High oxigen content can explain the higher metabolism (and mobility of animals), but cannot increase the durability of organic materials in the bones and muscles.
IMHO, the content of bones and muscles is similar for dinosaurs and modern reptiles.