How did big Pterosaurs get off the ground?

[Rexy]

Just like dinosaurs, pterosaurs varied greatly size from the tiny Nemicolopterus to the giant Quetzalcoatlus. I can just imagine tiny pterosaurs flitting through the tree-tops and how amazing it must have been to see the giant pterosaurs in flight, but I sometimes wonder how the big pterosaurs managed to get off the ground. I've often imagined them simply jumping off the edge of a cliff, but some palaeontologists have suggested they took flight by using all four limbs to make a standing jump into the air. What do you think?

[Leyster]

Like this

Pterosaurs used the strenght of the forelimb to catapult themselves into air, using the same muscles that are well developed for the flight, while birds are restricted to use their hindlimbs. This is, by the way, the reason why birds never attained the size of the biggest pterosaurs.

[Rexy]

The forelimbs must have been very strong.

[stargatedalek]

Please stop posting every comment in bold. The first post of the topic is one thing, but it's very distracting.

[Stegotyranno420]

I don't see anything wrong with @Rexy posting in bold letters.

[Lanthanotus]

Well, in other forums I am active in, bold type is seen as the equivalent of shouting. So there it would be seen as rude.

[andrewsaurus rex]

Like this

Pterosaurs used the strenght of the forelimb to catapult themselves into air, using the same muscles that are well developed for the flight, while birds are restricted to use their hindlimbs. This is, by the way, the reason why birds never attained the size of the biggest pterosaurs.

Nyctosaurus was pretty small, is the suggestion that larger pterosaurs like Anhanguera and Pteranodon took to the air that way?  If so, i'm skeptical that would work.

[stargatedalek]

Like this

Pterosaurs used the strenght of the forelimb to catapult themselves into air, using the same muscles that are well developed for the flight, while birds are restricted to use their hindlimbs. This is, by the way, the reason why birds never attained the size of the biggest pterosaurs.

Nyctosaurus was pretty small, is the suggestion that larger pterosaurs like Anhanguera and Pteranodon took to the air that way?  If so, i'm skeptical that would work.

They don't just push off with the downstroke, they also swing their weight forwards by jumping with the hind legs. They are essentially "falling" and using their weight to swing upwards while pushing off with the forelimbs.

[Lanthanotus]

It could be argued that large species would require a certain environment to take off, as modern albatrosses for example do to. This could for example either be a slope or cliff or a certain direction and strength of the wind.

[suspsy]

Please stop posting every comment in bold. The first post of the topic is one thing, but it's very distracting.

I second this. It's totally unnecessary.

[Die_Maulquappe]

Just like dinosaurs, pterosaurs varied greatly size from the tiny Nemicolopterus to the giant Quetzalcoatlus. I can just imagine tiny pterosaurs flitting through the tree-tops and how amazing it must have been to see the giant pterosaurs in flight, but I sometimes wonder how the big pterosaurs managed to get off the ground. I've often imagined them simply jumping off the edge of a cliff, but some palaeontologists have suggested they took flight by using all four limbs to make a standing jump into the air. What do you think?

The reason why the giant prehistoric birds like Argentavis never again reached the size of the largest pterosaurs is due to this.
Birds have very strong flight muscles but unfortunately no longer have the opportunity to support themselves on land.
They can only use the strength of your front limbs for flying.
Their hind legs are relatively weak.
pterosaurs, on the other hand, can use their fore and rear limbs to take off and thus use their strong fore limbs to push themselves forward like a catapult and then swing themselves into the air. Even Quetzacoatlus didn't necessarily need a cliff, but certainly certain surroundings for an optimal start.
Under dinosaur lectures on youtube https://www.youtube.com/channel/UCYeF244yNGuFefuFKqxIAXw
gives an interesting lecture on this.

The same applies to the growth in size of the sauropods, which far surpassed mammals not only because of their lightweight construction but also because of their digestive system.

Mammals like the elephant have to chew. To do this, they need large molars and strong jaws, which results in a large head.
Sauropods snaked everything down, they had relatively small heads and teeth to pluck and cut ... not to chew.

Here is a brief explanation.
https://www.jstor.org/stable/2400838

many greetings Matze: D

[stargatedalek]

It could be argued that large species would require a certain environment to take off, as modern albatrosses for example do to. This could for example either be a slope or cliff or a certain direction and strength of the wind.

This seems unlikely for Pteranodon given its diving adaptations, as it would need to swim back to shore.

[Lanthanotus]

It could be argued that large species would require a certain environment to take off, as modern albatrosses for example do to. This could for example either be a slope or cliff or a certain direction and strength of the wind.

This seems unlikely for Pteranodon given its diving adaptations, as it would need to swim back to shore.

Not necessarily, albatrosses also do not need to swim back to the shore, however, they have big difficulties to take off under certsin circumstances.

Also, with pterosaurs we are talking about a great variety of "large" with Pteranodon being 30 to 40% smaller than Quetzalcoatlus for example while still being much larger than any flying life form we have today.

My point is just, that as in recent birds with their totally different body plan, pterosaur strategies to take off most certainly varied from the smaller to larger species and that most certainly the conditions of their surrounding environment had a grewing importance with greater body size.

[andrewsaurus rex]

Interesting discussion.  Pterosaur wings, as understood today, were long with a narrow chord....the wandering albatross wing is a decent analogue.  Albatross can take off from the water, but must wait for a stiff breeze and face into wind.  On land they use cliff and other elevations for taking off.  This is because Albatross wings are optimal for gliding...they look somewhat like the wings of a sailplane...long and skinny.  And so it is with most pterosaur wings.

This suggests pterosaurs would be great gliders, probably with long endurance but not great flappers.  And flapping is what is needed when taking off.  No matter how high large pterosaurs could jump with their limbs, they would have to flap like crazy to stay in the air, before they hit the ground again.  And their wings were not built for or useful for flapping like crazy.  So I think the larger pterosaurs, say over 7kg or 8kg, would probably have needed another strategy for takeoff, rather than jumping up.

As much as I would love to believe Pteranodon dove into the water after prey, i'm not convinced. I know all the arguments in favour of this but there are lots of arguments against it too.  And I find it hard to believe a soaking wet Pteranodon could take off from the water, given its wing shape and design, especially if I am asked to believe they needed to be able to jump into the air in order to be able to take off....clearly not possible on water.

My feeling is that small pterosaurs could have used the jumping technique to become airborne, but larger ones would need another strategy....ie jumping out of trees, off of cliffs or other elevations or some other strategy.  And Quetzalcoatlus  may have been a land dweller for the most part, perhaps only taking to flight rarely, say for a migration, and when conditions were ideal.

[Rexy]

There's a theory that Pteranodon dipped for fish while swimming rather than while flying, but that makes me wonder how it would get back in the air with no solid ground to push off from.

[stargatedalek]

There's a theory that Pteranodon dipped for fish while swimming rather than while flying, but that makes me wonder how it would get back in the air with no solid ground to push off from.

It definitely didn't "dip" for fish while flying, no known pterosaur did. Doing that requires very specific anatomy and even then the birds that do it often injure themselves by accident while fishing in that way. It's pretty common for skimmers to have fractured or even broken bills.

[andrewsaurus rex]

Rexy said swimming, not flying.

[ITdactyl]

Quad launch seems to be a hard sell to the public since the only living animals that use this launch technique are a few species of microbats, plus the lack of [pop] media showing the larger pterosaurs quad launching.*

*granted this remains a hypothesis. Since we have trackway fossils showing a pterosaur landing, one can hope a fossil will also be found showing a takeoff. 

Here are some nice easy reads about quad launching in pterosaurs.

https://lorenabarba.com/blog/student-guest-blog-post-pterosaur-quad-launch/
http://pteroformer.blogspot.com/2015/05/quadrupedal-launching-in-bats-and.html

A formal paper, if that's what you prefer:
https://epub.ub.uni-muenchen.de/12011/1/zitteliana_2008_b28_09.pdf


art by James Brown, for the research activity of Dr Collin Palmer

quad launch in a pterosaur:
https://www.youtube.com/watch?v=CRk_OV2cDkk

quad launching bat, showing a failed first attempt:
https://www.youtube.com/watch?v=kIl_bYFMr8o

As much as I would love to believe Pteranodon dove into the water after prey, i'm not convinced. I know all the arguments in favour of this but there are lots of arguments against it too.  And I find it hard to believe a soaking wet Pteranodon could take off from the water, given its wing shape and design, especially if I am asked to believe they needed to be able to jump into the air in order to be able to take off....clearly not possible on water.

A lot of water birds use something similar to quadlaunching when they need to get out of water in a hurry. They push both with their wings and webbed feet in tandem, until they get enough clearance for a flight stroke.  'Not hard to imagine the oceanic pterosaurs doing the same thing (though they still probably can't do the near vertical leaps that some birds do).
https://www.youtube.com/watch?v=JaBi4BaZmkk

[Lanthanotus]

The main problem with all this remains, that we have neither a bat nor bird that is anyway near the measures (both in size and weight) of large pterosaurs. So observations of these recent animals allow only limited insight into the flight (and take off) physics of these amazing animals and can`t simply be "copied and pasted". The muscle physiology/anatomy/metabolism to propel such weights and measures into the air, no matter from which surface must have been vastly different even from our most developed (metabolism wise) vertebrates today, the birds.

[ITdactyl]

Agreed.
The vampire bats and ducks are only there to provide "insight", a layman's visual aid of sorts. No one's really claiming that because microbats quad launch when grounded, then pterosaurs must have too. (though it's interesting that people easily assume that pterosaurs launched like birds just because)

I linked the 2008 paper because it details the reasons why quad launching is possible for pterosaurs, but it doesn't say that they definitely did. While a bipedal launch is not impossible for the tiny pterosaurs, the giants would have needed a different strategy since the biomechanics of their hind limbs prevent them from relying on a bipedal launch (whether leaping or running).

I will concede though, unless we find trackways that show a "takeoff", all we'll ever have are the computations.