Pterosaur physiology
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chornedsnorkack
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Because pterosaur´s adaptations to insect hunting are more specifically about "pterosaur physiology".
There are no stomach contents of juveniles at least.
This, however
From Egg to Grave: Clues Reveal How Baby Pterosaurs Grew Up
Several new fossils paint a very detailed picture of how pterosaurs were born, lived and died, yet we still don't know how they got the energy to fly.
www.livescience.com
Any full text publication, debunking?
chornedsnorkack
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Full text like this:
AE35Unit
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Well not quite. Birds are descended from late dinosaurs. The physiology is somewhat different, although I do call birds modern dinosaurs
Re the material you quote above, when Chris expresses an opinion, he is almost always correct. When he makes a rare mistake, as in the Pteranodon split tail vertebrae, he invariably catches and eventually corrects it. He knows more about pterosaurian skeletal structure than anyone else, bar none.
Re the statement about still not knowing how pterosaurs got the energy to fly, Mike is the only one mentioned in those papers who has in depth knowledge of pterosaur flight mechanics - and he didn't say that. Mike did say recently that there are only four people who have world class knowledge of both pterosaur flight mechanics and their biomechanics. He is one of the four and is probably right about that. Ask him whether we know how they got the energy to fly. You might also ask him who the other three guys are.
Re Quetz living to be a hundred - both morphs? That statement was just speculation based on physical size and assumed cold blooded reptilian growth rates with no supporting evidence.
Re inferences about warm bloodedness, yeah, they were warm blooded, but they mostly flew using styles equally suited to cold blooded animals. I've always thought that interesting. Could be an adaptation to allow travel at high altitudes for an increase in TAS. I dunno.
Re Quetzie being a thermal soarer, yeah they could. But they were equally well suited to using cloud streets and dynamic soaring.
BTW, northropi is far lighter than Mark's projections. He severely overestimates the volume of northropi's torso and therefore the torso mass. But he is a super nice guy and I like him a lot.
Re the statement about still not knowing how pterosaurs got the energy to fly, Mike is the only one mentioned in those papers who has in depth knowledge of pterosaur flight mechanics - and he didn't say that. Mike did say recently that there are only four people who have world class knowledge of both pterosaur flight mechanics and their biomechanics. He is one of the four and is probably right about that. Ask him whether we know how they got the energy to fly. You might also ask him who the other three guys are.
Re Quetz living to be a hundred - both morphs? That statement was just speculation based on physical size and assumed cold blooded reptilian growth rates with no supporting evidence.
Re inferences about warm bloodedness, yeah, they were warm blooded, but they mostly flew using styles equally suited to cold blooded animals. I've always thought that interesting. Could be an adaptation to allow travel at high altitudes for an increase in TAS. I dunno.
Re Quetzie being a thermal soarer, yeah they could. But they were equally well suited to using cloud streets and dynamic soaring.
BTW, northropi is far lighter than Mark's projections. He severely overestimates the volume of northropi's torso and therefore the torso mass. But he is a super nice guy and I like him a lot.
While I'm thinking about it, in the Azdharchidae, there is a very specific relationship between the size of the deltopectoral crest and the size of the scapulocoracoid.
And there is a very specific size relationship between the scapulocoracoid and the torso.
So, if you have a humerus with intact dp crest, you know how big the torso was. We've got a northropi humerus with intact crest.
And there is a very specific size relationship between the scapulocoracoid and the torso.
So, if you have a humerus with intact dp crest, you know how big the torso was. We've got a northropi humerus with intact crest.
chornedsnorkack
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I was able to spot only "Mark" - Mark Purnell. Not the two names you approve. The other authors seem to be Jordan Bestwick, David Unwin, Richard Butler, Donald Henderson. No Chris or Mike.
chornedsnorkack
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An inquiry I posted in the impact thread, and that seems to have been neither answered nor transferred:
"How do pterosaurs breathe"?
Flighted birds rely on a heavy keel on their breast. Note that the
keelbone of a bird supports both the muscles for a downstroke and the
muscles for upstroke - the muscles for upstroke are on bird´s chest,
not on its back.
Bats are different from birds in some respects. For example, the
distribution of fingers in bat´s wing is rather different from that of
a bird wing. And IIRC, the arrangement of flight muscles is different
for a bat. The downstroke muscles are on the breast, and supported on
keelbone. But the upstroke muscles are on the back.
Note that biggest extant fruitbats are rather smaller than biggest
extant birds.
The arrangement of fingers in the wing of a pterosaur is again
different from a wing of bird or bat. But what is the pectoral girdle
of a pterosaur like? And where are the flight muscles supposed to have
gone?
Bats do not have avian respiratory system. How do pterosaurs breathe?
"How do pterosaurs breathe"?
Flighted birds rely on a heavy keel on their breast. Note that the
keelbone of a bird supports both the muscles for a downstroke and the
muscles for upstroke - the muscles for upstroke are on bird´s chest,
not on its back.
Bats are different from birds in some respects. For example, the
distribution of fingers in bat´s wing is rather different from that of
a bird wing. And IIRC, the arrangement of flight muscles is different
for a bat. The downstroke muscles are on the breast, and supported on
keelbone. But the upstroke muscles are on the back.
Note that biggest extant fruitbats are rather smaller than biggest
extant birds.
The arrangement of fingers in the wing of a pterosaur is again
different from a wing of bird or bat. But what is the pectoral girdle
of a pterosaur like? And where are the flight muscles supposed to have
gone?
Bats do not have avian respiratory system. How do pterosaurs breathe?
Claims that Quetz was a thermal soarer seem to be based on a couple of assumptions...
1) the trailing edge of the outboard wing was roached (it wasn't - pterosaur wings can't support roach)
2) the trailing edge attached to the ankle or knee and was very broad at the elbow so that wing area was high and aspect ratio was relatively low (it wasn't attached at the ankle, and no preserved pterosaur wing membrane has been found in which the trailing edge at the elbow is located more than half the length of the humerus behind the elbow, therefore area was lower and aspect ratio higher, which reduces capability for thermal soaring - though they were still quite capable of thermal soaring)
Actual aspect ratio (span squared divided by area) appears to have been about the same, perhaps a bit higher) as albatrosses, on the approximate order of 16.5 to 17. Since they could also achieve a bit higher lift coefficient than albatrosses and Frigate Birds, their dynamic soaring ability would have been as good, perhaps a bit better. Consequently, they weren't limited as implied.
1) the trailing edge of the outboard wing was roached (it wasn't - pterosaur wings can't support roach)
2) the trailing edge attached to the ankle or knee and was very broad at the elbow so that wing area was high and aspect ratio was relatively low (it wasn't attached at the ankle, and no preserved pterosaur wing membrane has been found in which the trailing edge at the elbow is located more than half the length of the humerus behind the elbow, therefore area was lower and aspect ratio higher, which reduces capability for thermal soaring - though they were still quite capable of thermal soaring)
Actual aspect ratio (span squared divided by area) appears to have been about the same, perhaps a bit higher) as albatrosses, on the approximate order of 16.5 to 17. Since they could also achieve a bit higher lift coefficient than albatrosses and Frigate Birds, their dynamic soaring ability would have been as good, perhaps a bit better. Consequently, they weren't limited as implied.
The question of how pterosaurs breath was answered, but it may have gone off into never never land as Brian was shuffling stuff around.
Pterosaurs have a fixed ribcage, it doesn't expand and contact like mammals. Air is pumped by the diaphragm moving fore and aft when the spine is flexed down and up by the four spinal vertebrae that aren't fused (you can see those in the photo of the Quetz skeletal torso that I posted earlier - I'll attach it again). Pterosaur lungs tend to be relatively smaller than bird lungs because their torsos are smaller, so the volume of air moved by each breath is relatively smaller. Both are highly pneumatic, pterosaurs moreso than birds. Air is cycled through the airsacs similarly. Pterosaur necks tend to be much longer than bird necks, increasing the relative length of the windpipe and the volume of air that gets recycled rather than exchanged with each breath - so in general pterosaurs are seeing a bit higher concentration of CO2 and lower concentration of oxygen than birds. The combination means that their ability to oxygenated their blood and carry away CO2 is more limited than in birds. Pterosaurs could flap more powerfully, but not for as long. That said, pterosaurs didn't spend as much time flapping. They didn't have to. When flapping, exhalation was synchronized with the downstroke, inhalation with the upstroke.
Here's a torso of the small morph of Quetz. It is very robust, but quite small for an animal with its 4.8 meter wingspan (notice the 5cm scale bar). The two unfused vertebrae in front of the shoulder are part of the neck, CV8 & 9. The break in the spine back near the pelvis is just that, deliberately broken to make it easier to cast.
Pterosaurs have a fixed ribcage, it doesn't expand and contact like mammals. Air is pumped by the diaphragm moving fore and aft when the spine is flexed down and up by the four spinal vertebrae that aren't fused (you can see those in the photo of the Quetz skeletal torso that I posted earlier - I'll attach it again). Pterosaur lungs tend to be relatively smaller than bird lungs because their torsos are smaller, so the volume of air moved by each breath is relatively smaller. Both are highly pneumatic, pterosaurs moreso than birds. Air is cycled through the airsacs similarly. Pterosaur necks tend to be much longer than bird necks, increasing the relative length of the windpipe and the volume of air that gets recycled rather than exchanged with each breath - so in general pterosaurs are seeing a bit higher concentration of CO2 and lower concentration of oxygen than birds. The combination means that their ability to oxygenated their blood and carry away CO2 is more limited than in birds. Pterosaurs could flap more powerfully, but not for as long. That said, pterosaurs didn't spend as much time flapping. They didn't have to. When flapping, exhalation was synchronized with the downstroke, inhalation with the upstroke.
Here's a torso of the small morph of Quetz. It is very robust, but quite small for an animal with its 4.8 meter wingspan (notice the 5cm scale bar). The two unfused vertebrae in front of the shoulder are part of the neck, CV8 & 9. The break in the spine back near the pelvis is just that, deliberately broken to make it easier to cast.
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chornedsnorkack
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Where are the upstroke muscles of pterosaurs? On the chest between the downstroke pectoral muscle and ribs, as in birds, or on the back, as in bats?
The back. That's why the glenoid is moved down on the scapulocoracoid - to improve the alignment of the upstroke muscles.
And the downstroke muscle layout is a bit different from birds. No big keel on the sternum for example. Also, the coracoids attach to the cristospine in tandem, not opposed.
And the downstroke muscle layout is a bit different from birds. No big keel on the sternum for example. Also, the coracoids attach to the cristospine in tandem, not opposed.
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chornedsnorkack
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So, since the ribcage is rigid, flight muscles in flapping flight did not contribute to breathing. The breathing during flapping flight had to be done entirely by other muscles - abdominal? diaphragm?
"The breathing during flapping flight had to be done entirely by other muscles"
I'm assuming that's a joke - is it?
On the off chance that you are serious, during flapping, the shoulders bob up and down relative to the head and hindlimbs at about 0.2 g. That bobbing, powered by the flight muscles as the lift cycles, flexes those 4 unfused vertebrae in the spine up and down, which moves the diaphragm fore and aft. When soaring, abdominal muscles and/or an occasional flap would do it.
I'm assuming that's a joke - is it?
On the off chance that you are serious, during flapping, the shoulders bob up and down relative to the head and hindlimbs at about 0.2 g. That bobbing, powered by the flight muscles as the lift cycles, flexes those 4 unfused vertebrae in the spine up and down, which moves the diaphragm fore and aft. When soaring, abdominal muscles and/or an occasional flap would do it.
chornedsnorkack
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Ah, thanks - now I get it! The flexing of the spine does the pumping.
So the pterosaur breathing is inefficient compared to birds due to 1) comparatively small torso and lungs and 2) comparatively long neck and much dead airspace in neck.
When would a pterosaur in flapping flight get tired - 10 seconds, 10 minutes, 10 hours? All of these are compatible to adaptation to flight.
So the pterosaur breathing is inefficient compared to birds due to 1) comparatively small torso and lungs and 2) comparatively long neck and much dead airspace in neck.
When would a pterosaur in flapping flight get tired - 10 seconds, 10 minutes, 10 hours? All of these are compatible to adaptation to flight.
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