Why we think giant pterosaurs could fly (2018) | Hacker News Reader

Why we think giant pterosaurs could fly (2018)

markwitton-com.blogspot.com

129 pointscurtis51 comments

This is an exceptionally kickass piece of popular science writing. Chock full of interesting facts that (AFAICT) preserve scientific objectivity and skepticism without getting too technical for a lay audience to follow.

Also:

> Mike has presented calculations that these giants would have sufficient on-board energy resources to travel the planet, their speed and flight range being sufficient to ignore most geographical barriers.

This made me, sitting at my computer in 2019, a little bit scared of pterosaurs. The thing can come from the other side of the world and gobble you up like a snack.

There are plenty of birds that travel between southern Africa and Europe every year. Sure, they take breaks unlike the Pterosaur would've, but still, it's not that special.

They're not as big as a flying giraffe with a gigantic beak, though.

There was a stork that migrated to Europe with an African spear lodged through it. That's something.

Actually, many of them: https://en.wikipedia.org/wiki/Pfeilstorch

..and this was how we learned about migration? That’s such an absurd way to discover it

Seems very reasonable to me. Here are some other theories at the time from the wiki article about where birds came from:

"Some theories of the time held that they turned into mice, or hibernated at the bottom of the sea during the winter, and such theories were even propagated by zoologists of the time."

This was accidental, but I think tagging individual birds to make them identifiable by humans is still the primary way we learn about migration. The alternative of continuously tracking individual birds wasn’t possible until late 20th century and I think still is fairly expensive.

Sure, it's just a comical predecessor to tagging

There was a very interesting In Our Time podcast on this if you are interested in how our knowledge of bird migration evolved - https://www.bbc.co.uk/programmes/b08wmk5j

Yes, that's where I first heard of it. It's a great podcast and worth recommending!

>first and most famous Pfeilstorch was a white stork found in 1822

>Before migration was understood, people had no other explanation for the sudden annual disappearance of birds like the white stork and barn swallow. Some theories of the time held that they turned into mice

1822 seems far too late

Obviously, but GP mentioned that they found the feat of flying across the world particularly impressive/scary, so I thought they might not be aware that super many birds do that today and it's awesome and amazing :-)

The wording suggested to me that the pterosaurs in question could do it without stopping, though I probably misinterpreted it. But it's really the combination of that with the "giraffe-sized monster with a beak" angle mentioned by mcv.

No, they really could fly thousands of miles without stopping. They may have stopped to sleep, but there are plenty of birds that don't.

You’re spot on that this is excellent pop sci writing.

However, I’d argue that this is the right level of technical detail for a layman. Just consider how much denser a typical academic paper is. This strikes a great balance in citing lots of research and offering accessibile summaries of that research. This keeps the reader from getting lost in jargon and references, but gives them the opportunity to dig in if they wish.

I think that science writing in this vein is much more likely to catch the public’s attention that the shallow science articles we typically see. It doesn’t insult the reader’s intelligence, rather it invites it.

> However, I’d argue that this is the right level of technical detail for a layman.

Uh, isn't that what I said? :)

Yeah, I guess I’m not a great reader. :)

As an aside, one of their papers (https://journals.plos.org/plosone/article?id=10.1371/journal...) has a great diagram of the wing parameters:

https://journals.plos.org/plosone/article/figure/image?id=10...

> This made me, sitting at my computer in 2019, a little bit scared of pterosaurs.

Wow, I wasn't even aware there were pterosaurs this large. I thought the Pteranodon was the largest of them all, but Quetzalcoatlus and Hatzegopteryx dwarf it. They are really impressive.

I'm not scared of these giant reptiles though, but awed. It'd be awesome if it was possible to see one of them in real life. I wonder if people in the near future will feel this way about lions and tigers, "such a shame I missed them!". But even in that sad future, at least there would be video recordings.

I tend to think atmospheric pressure was higher then:

https://gdesilvestri.wordpress.com/2015/10/13/was-the-atmosp...

Yeah. The assumption that the Earth's environment parameters have been stable for billions of years is bunk. (Especially ironic if the person is railing about 'global warming' at the same time.)

Implicit in your sentence is however an assumption that there was any life comparable to today's during the "billions of years" which is false. More than just 500 million years ago there were not even plants on the land:

https://en.wikipedia.org/wiki/Timeline_of_plant_evolution

So it's simply wrong mentioning "billions of years" when humans worry for the environment in which they can live while depending on it.

For most of the "billions" of years on Earth, there wasn't anything on land, and the "life" in oceans was not something we understand as today's life, and the environment could not support our life (as in, there was not even enough oxygen!). The Earth started to "resemble its present state" only less than 400 million years ago:

https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_h...

Human civilizations exists only less than ten thousands of years, during which the climate was very stable (until the recent human influences):

https://en.wikipedia.org/wiki/History_of_the_world

The writing of that author you link to nicely matches the description from the other article of the author posted originally (Mark Witton):

http://markwitton-com.blogspot.com/2019/02/how-to-spot-palae...

Mark Witton:

"Another major red flag common to all cranks is their frequent comparison between themselves and scientists who received establishment pushback against their ideas - Wegner, Galileo, Darwin and so on."

The article you posted:

"It is admirable how the persistent efforts of a handful of Wegener’s converts were able to overcome the arrogance of the majority." ... "This present article is having a somewhat similar history."

Mark Witton:

"Saving the best until last: yes, unbelievable as it is, there are individuals who suggest mainstream scientists are somehow organising against them to suppress their work. While maybe not imagining something as sinister as the Big Pharma conspiracy, some cranks infer that palaeontology is governed by individuals who dictate what is and what isn't acceptable science, and who forbid the publication of work that challenges the status quo."

The article you posted:

"This paper in its various versions has had a battered history. Here are the journals that were sent this paper and either returned it unread or just discarded it." "It seems that this paper is too radical for today’s journals."

By the way, the article from your link is not by the guy who posted the copy of it on his blog, but by a much older chemist:

https://issuu.com/pedrott600re/docs/levenspiel.com_octave_ol...

Wouldn't that just mean everything was more buoyant? How does that hurt the conclusion?

Here's another article discussing various theories about past earth's atmosphere:

http://pubs.acs.org/subscribe/archive/ci/30/i12/html/12learn...

Actually a newer “version” by the same chemist who's text was just copy pasted by that Ing. (i.e. Engineer) guy (who names that copy-pasting “A small Tribute”)

That (the newer one, from your link) was published by: “Chemical innovation 30 (12), 50-55, 2000”

Compare with the peer reviewed, not confirming "many times higher pressure" claim:

http://science.sciencemag.org/content/342/6154/101

"We show from the analysis of nitrogen and argon isotopes in fluid inclusions trapped in 3.0- to 3.5-billion-year-old hydrothermal quartz that the partial pressure of N2 of the Archean atmosphere was lower than 1.1 bar, possibly as low as 0.5 bar, and had a nitrogen isotopic composition comparable to the present-day one. These results imply that dinitrogen did not play a significant role in the thermal budget of the ancient Earth and that the Archean partial pressure of CO2 was probably lower than 0.7 bar."

There is sure possibility that the pressure changed through the times, but not alk “proofs” are real proofs.

One point of the article is that there's no need for a higher athmospheric pressure to explain pterosaurs flight. It would work fine under the conditions we have today.

GOOD point. Also o2 was higher leading to more compact powerful muscles?

If some deactivated ancient genes reactivate, due to high co2, we are going to have that again :D

As a bonus, the article explains why we never got birds that big: birds depend on their feet for help launching, where the extra leg musculature competes with wings in the weight budget. The heavy muscles needed for azhdarchid launch are also flight muscle.

Be sure to watch the quad launch video on how they believe pterosaurs actually took off: https://www.youtube.com/watch?v=ALziqtuLxBQ

Seems like a pretty poor model. Note that at the second it leaves the ground the wings aren't in a position to generate lift. Yet somehow it floats away. The wings need a down stroke to generate lift at close to zero ground speed.

I don't doubt the quad launch, just that animation of it.

Like the article says, they jump, then flap, which is also what birds and bats do.

Except birds jump with wings in position to flap. The quad launch would require moving wings into position which not only takes time, but also counteracts by providing drag.

I trust the simulations mentioned in the article take this into account, but the grandparent is right that this is not it all obvious from the video. In fact the video shows very leven flight motion while the wings are brought up, which absolutely would not be the case.

You did notice that the video just shows the bones, right? Flight surfaces and muscles will cost you extra.

The key bit is right at the end, showing launch in real time. There is no descent for lack of lift because there is no time for it to happen in. While the animal is still rising from the jump, the wings swing out and take up the load, in a fractional second.

It would be terrifying to have it happen toward you, even as it swept over.

I would expect that this model is informed by the several species of bat that use this method, and by the size and structure of the limb bones, which would be a clue to the forces being used.

If the animal can just get itself gliding, I think it is possible to continue generating lift even while raising its wings into position for a downstroke - what it needs to do is maintain a positive angle of attack while doing so. At least when they are not hovering, birds continue to generate lift on the upstroke.

A headwind would make it easier, and perhaps that or a downslope might have been necessary.

> Yet somehow it floats away.

Yes, that's a jump. This is a very light animal relative to its wing strength, it should be able to jump very high.

By the article, those animals should be stronger (relatively to their weight) than birds, only comparable to bats, and most people simply don't believe the kind of maneuvers bats can do.

If you're looking for more details, check out On the Size and Flight Diversity of Giant Pterosaurs, the Use of Birds as Pterosaur Analogues and Comments on Pterosaur Flightlessness: https://journals.plos.org/plosone/article?id=10.1371/journal...

i knew they were big, but oh man I didnt know they were that big, amazing

"Predicted giant flight velocities exceeded 90 kph and, in that 90 second flapping burst, giant azhdarchids would cover several kilometres - plenty of distance to seek areas of uplift such as deflected winds or thermals."

I have a small issue with this statement. 90kph for 90 seconds is only enough for a bit more than 2km of flight and probably even less since accelerating to this speed would take not be almost instantaneous either.

"Several" may have been an exaggeration, but their quadrapedal launch makes it look like they accelerated very quickly, unlike what we naturally envision when thinking of birds.

(FTA) https://www.youtube.com/watch?v=ALziqtuLxBQ

2.25 km is a hell of a long way for an animal to get in 90 seconds, no matter how you slice it.

Perhaps ptersaurs could also use their long necks and big heads to start their center of gravity higher before launch?

Dropping a mass (head/neck) from higher up while launching keeps the center of gravity about the same requiring much less effort for the critical "get off the ground" phase.

Perhaps the article addressed this; I'm only halfway through.

Pelicans, which have always reminded me of pterosaurs, seem to do this slightly when they launch.

Video I took the other week of one: https://serio.com.au/images/projects/eyre-peninsula-videos/S...

It's very different actually - the pelican, as every other bird, uses its hind legs to push off, while the pterosaurs (and some bats) push off with their forelegs - and the latter ones are very powerful and can be re-used for flight, unlike the powerful hindlegs of large birds which are just dead weight when they're airborne.

If the muscles could do it it would be better to start head low and get it moving upwards fast as possible while making ground contact for a lot of upwards momentum, then at apogee of head height drop it.

"The second source of frustration is that, away from technical literature, discussions of giant pterosaur flight frequently suffer from major cases of Dunning-Kruger effect, especially when parties have knowledge of planes. I've experienced this a lot in my career, and not just in the wilds of social media: many of my TV and film consultancy jobs have required defending basic tenets of pterosaur anatomy - even their basic, there-for-all-to-see proportions preserved in articulated fossils - to folks who just can't or won't believe what the fossils show. Having a casual understanding of engine-driven man-made flying machines does not equate to knowing all there is about everything that has ever flown, but you would not know this from some conversations."

It's nice to know that humanity is the same everywhere.

As for me, I'm more curious about their heads. For an animal the size of a giraffe, they're feckin' huge. What's up with that?

Reading through this, it reminds me of pointless arguing of whether superman can beat goku. There's a lot of logic and maths, from both sides, yet in the end it would be impossible to know the answer.

Um, no. There is an established scientific community around pterosaurs. The difference between pterosaurs and Superman is that between a natural historical entity and a comic book character.

Logic and maths don't work for Superman and Goku. Logic and maths do work for giant pterosaurs though. That's a big difference.

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