A question about giant pterosaurs taking off.
- Thread starter Angilion
- Start date
Soldato
Right. So, now you need to show how the earth gained significantly more mass (a smaller earth doesn't require as much mass to have an equal amount of gravitational pull at the surface). You also need to show how this mass was somehow absorbed into the earths core.
What do you mean by energy dynamics? That begins to sound like some significant arm waving.
No one said it was going supernova. Gravity at the surface of an object has a direct relationship to it's radius. The bigger the earth (with the same mass) the less gravity at the surface. By claiming lower gravity, and smaller earth, the earth needs to have been massively lighter.
How do you know it's rotating faster now? Earths rotation is actually slowing down, and there's no good reason to believe that it was going even slower back then (and although to a very tiny degree, that increases the gravitational effect, so we now need an even lighter earth). Perhaps you meant it was going faster back then, which it was, but not by very much, I think days were about an hour shorter, and a long way from having a significant effect on the gravity (which I have already pointed out).
It's a non issue in this speculation - if we suddenly had less gravity now, in the next five minutes, for us, humans that would be an issue, but density of the atmosphere is also dependant on temperature, composition and mass of the atmosphere and where's our IPCC hockeystick graph on that?
Being able to breath is a non-issue now. Yet I'm sure your argument was also including the respiratory and circulatory systems, which are greatly effected by atmospheric density. I don't know if you've ever spent any time over 3000 meters, but I'm telling you, it's a big deal. There's a reason you don't find large land creatures over 6000m.
The density of the atmosphere is directly related to gravity. Half it, half the density. And yes, temperature does make a difference, only it's making a difference in the wrong direction for you. We can tell average temperatures back then, and compare it to now. Now it's under 15C, back then it was 30C+. Warmer air = less dense. Oxygen is slightly more dense than nitrogen, and there was more oxygen back then, but we're not talking about bringing us down from very thin atmospheric levels to something more breathable.
By half is just one of the speculations, yes, you said 0.4g, so even less.
Have you seen the biomechanical computer models? I'm finding plenty of people that seem to believe it's possible, and giving reasons as to why. A quick google scholar search will show you plenty, can you link me to some of yours. No need for scifi materials, just bird like bones (and again, isn't it funny how a branch of dinosaurs went on to be birds!).
Elephants are bloody fast, I've been sat on top of a jeep driving away from charging elephants before, and you really have to motor to leave them behind. T-rex is thought to be much much slower, evidence is suggesting t-rex was more a scavenger than an active hunter, vulture more than eagle. Poor eyesight, not that fast, but excellent sense of smell. I'm sure he'd take a chunk out of a live animal too if he could, but why bother if there's something already dead to enjoy.
Biomechanicists (is that the word?), believe they know how dinosaurs operated, grew so large, survived that large etc etc. Are there still new things being found? Absolutely! Have the answered everything? Absolutely not. The whole point of science is there's still unanswered questions. But since you invoked it, we have Occam's razor here. We can have a mostly resolved biology issue as to how they got so large. Or we can throw away our understanding of planet formation, gravity etc etc etc. One is a lot simpler than the other here. And it's not saying that the earth was somehow half the mass, smaller, spinning slower, yet still magically having a dense atmosphere. Oh, and not giving us evidence that any of this was the case.
The gravity at the surface, yes. Because the amount of gravity would be the same (same mass) and the surface would be further away from the centre of gravity (bigger planet). Gravity follows an inverse square law, so the gravity at the surface would be a fair bit lower if the same planet was bigger, lower by a much larger proportion than the increase in size of the planet.
It's gaining an extremely small (relative to the mass of the Earth) amount of mass from infalling debris. Which I knew already and which isn't relevant because the amount is far too small.
You're arguing that within the last few dozen million years Earth became significantly bigger (you don't specify how much, only that it's a significant amount) and that despite that increase in size the gravity on the surface increased by 250% because the Earth gained so much mass over that time that it more than offset the increase in size. So your claim rests on the assumption that the mass of the Earth has increased by at least 400% over the last few dozen million years. With no supporting evidence and no reasoning. Where did all that mass come from? We're talking about 3 quite massive planets worth of mass here. Not dust and tiny meteorites.
And you've added the Earth rotating faster for no explained reason despite getting bigger (which would slow the speed of rotation down due to conservation of angular momemtum) and despite the gravitational field of the sun slowing it down.
And you've ignored the effect on gravity on atmospheric density, which is significant and especially so when it comes to larger animals.
And all that because you don't understand how larger animals moved.
Soldato
majority of the earth weight is the core of iron afaik. specs of dirt or animals at the surface I dont imagine matters but source would help.
Biggest change from then to now would be oxygen levels, from maybe 40% back then to 28% now which altered insect size mostly. Not sure about birds but birds eat insects so maybe. There was a snake the size of a double decker bus which is hard to prove as their bones dont last but its not gravity we should probably debate but other factors which caused large alterations to now. Air Viscosity over gravity maybe
Soldato
I'm not reading through these walls of text.
Is it treadmills, jumping, falling into a glide from a cliff or an aircraft carrier catapult system they used?
Needs a poll.
Is it treadmills, jumping, falling into a glide from a cliff or an aircraft carrier catapult system they used?
Needs a poll.
This is so last week. Today we are challenging conservation of mass and assigning earth arbitrarily changing density/diameter
Soldato
There is no need for us to go around in circles gents. Smaller prehistoric Earth means smaller planet. As in smaller mass. I know you both understood me well the first time around, any chance you just raise smoke and dance with mirrors to cover up your previous "physics" faux pass of "larger Earth would have less gravity"? No need. I don't hold it against you, ok?
Socially distanced hugs. Awww....Faster rotating planet means of course less gravity on surface than if the same planet was rotating slower. But let's try this - if the prehistoric Earth was, just for the sake of argument, let's say, half the size, half the mass. But rotated as fast as our today's Earth (I personally subscribe to the idea that it was rotating a little bit slower, as you know). Would the gravity on the surface be higher or lower than now? Mhmm (nods) ...
So - let's not overcomplicate things - the ideas are very, very simple, I understood them after first read - but perhaps I'm just not explaining them very well. Also keep it mind these are not MY ideas, they were not invented by ME - these are theories proposed by various scientists, for long decades, with volume of work and titles to their name, and many of them spent their entire careers promoting these ideas. If anything it may be the early stages of what "quantum physics" did to classical newtonian, einsteinian physics - but for geology and palaeontology. If you will - everybody still nods to the Plate Tectonics, but slowly more and more scientists realise there are more holes in that theory than explanations:
1. The "Prehistoric Earth of dinos was smaller and lighter" thing. This theory is officially called Expansion Tectonics
What does this theory fix? From what I understand - apparently everything except for "where did the mass of todays Earth come from" (more about it later) and "what about density of air" (more about it one quote below) outrage on a OCUK subforum.
Age of theory? Old, almost as old as Plate Tectonics. It's been out there forever. Actually there was entire stream of German geologists postulating it in early twenties and thirties of 20th century, but due to the obvious "dude, wrong place, wrong time" reasons their volume of work weren't even translated for review up until sixties and peers re-approached their work only a few decades later.
Proof? Apparently many. For starters - obviously - biomechanics of palaeontology - it explains how dinos moved, their flight, why their bones aren't much bigger for the mass, why all animals and vegetation were bigger too.
It also "fixes" current large scale issues with plate tectonics theory - why continents that moved away from Pangea can be "matched" to both ends, while according to PT theory they could separate and move away from one end. Or since the tectonics pulled away Pangea apart to create Atlantic Ocean, why are there tectonic expansions around the Pacific rim (as in Pacific, if anything, should have shrunk to give way to Atlantic). The unaccounted up/down shifts (eg. eastern coast of North America) as proven by fossils and so on.
It matches well with other peer reviewed studies that couldn't find supporting for PT (like the "precambrian pole wandering") and unlike PT - it doesn't create necessity for some unsupported and unexplained by evidence shifts and movements, like for India to "crash" into today's Eurasia to create the Himalayas, yet Eurasia and India share the same fossils of many species from dinos to fungus gnats from the period when there was meant to be a massive volume of water between them.
It provides elegant solution to why all the oceanic floors are "young" - as in - only 100-250 mil years old vs 4 billion old continental crust and why we never found any oceanic sedimentation from before Palaeozoic and so on.
According to some - the same mechanism may be even responsible for expansion of other planets, like Mercury, equatorial rift on Mars or even NASA backtracking on their shrinking moon claim and admitting that our moon, geologically dead as Elvis - has undergone "recent" expansion (the "grabens") (I don't particularly like this particular part of speculation, but for transparency etc here it is..).
Essentially, as with all such work - you would have to give it a few hours of your time - read some papers, visit some sites, watch some videos, listen to a few badly amplified lectures, etc. You then have to go through all the debunking videos and sites as well, for balance. But it's a must.
Names, videos and papers to google: Prof. Samuel Carey and Dr. James Maxlow (geologists), John B. Eichler (mathematician and physicist, nuclear background), Giancarlo Scalera (geophysicist), Dr. Hugh G. Owen (geologist) , Cliff Ollier (geologist, geomorphologist), Karl-Heinz Jacob (chemist), Jan Koziar (geologist), Prof. Stefan Cwojdziński (geoscientist), Carl Strutinski (geologist), Stephen W. Hurrell (design engineer), William C. Erickson (physicist), Dr. Zahid A. Khan (geologist), Prof. Karl W. Luckert (philosophy), Prof. Wenbin Shen (geophysicist) and Sung-Ho Na (geoligist), Zahid Ali Khan and Ram Chandra Tewar (geologists)
2. Prehistoric Earth had different tilt.
Almost all the branches studying dinosaurs think dinos lived in the environment that was very warm (as Unseul mentioned before) and very stable. Dinos almost certainly never seen snow and probably the planet had no seasons to speak of, according to people who study prehistoric climates. So - there is one simple explanation - Earth tilt was still 0 or close to 0 deg. - et voila.
Unseul said:
Angilion said:
This view may be simply too narrow guys? Once again - you are describing density of today's atmosphere - if today's Earth suddenly had smaller gravity that could become a big deal to our current atmosphere ( for humans ).
Scientists from speculative paleo*-branches think they have a good picture of prehistoric climate, although in reality we probably know very little about the exact environment, size, mass, density, composition of atmosphere 64-300 millions of years ago - we definitely have no clue what requirements those animals had for "air". But even according to the current official narration dinos throughout most of their hegemony on Earth actually had less oxygen to breathe than we do now - up to a 1/4 less.
Although the levels of O2 are believed to be as high as 26% by the end of Permian (the theoretical Permian oxygen gigantism mentioned by everyone before in this thread), they were down to 15%-17% in Triassic, compared to about 21% now. If 5% extra was responsible for gigantism, did they shrink after it dropped to 16%? ? No. And btw - 15-17% corresponds exactly to something like 2000-3000 meters now, but I'm not going to count it as a point for "my" theory, because a) I don't think the science of estimating prehistoric atmosphere is sound enough either way b) the same people believe O2 fluctuated rapidly between as low as 17% and as high as 30% throughout Cretaceous and Jurassic and I don't think it actually particularly mattered to flora and fauna inhabiting Earth back then.
More oxygen, less oxygen in the "air" - the biggest animals inhabiting our planet clearly had no issues living with any variation of it and that's regardless of the whole "smaller Earth with less gravity" theory. We find their fossils literally everywhere across entire Pangea and post-Pangea landmasses - from todays Antarctica all the way to Siberia, so regardless of the "air", climates, temps, shapes and sizes of continents back then - all of them, including biggest sauropods lived through the entire prehistoric "always", everywhere and all the way to the end of it all. And that's again - according to the official climate-palaeontology-thingymagiggy-science data, not the "smaller earth" fringe. Bottom line - speculating about them getting lightheaded from air density may just fall in the "what if they breathed in methane, breathed out ignited napalm and couldn't feel temperatures at all through their dragon skin" territory.
Unseul said:
I've genuinely never read anyone say they knew why or how dinosaurs grew so large and survived so large. We got used to seeing Hollywood CGI of them walking and running and based on that treat it as if it were normal but from what I understand from the start to this day palaeontologists still agree it's a bit of a mystery to everyone studying them.
Bird bones don't really explain it or fix the problem - birds bodies are small and light, large dino bodies were just too heavy for the bones we find. 40 metre long, 80 tons of meat on four short legs in the centre and presumably the animal wouldn't knock itself dead if it fell, could stand up afterwards, could climb hills etc. In 1g that's either super light muscle tissue or super strong material for bones, definitely not the biotech we understand. One of the evidence presented for birds being descendants of dinos is (according to palaeontology) speculative presence of "airbags" - air sacs - in large sauropods and few other *sauruses. Air sacs were connected to lungs and were used for cooling. Or increased respiratory ability for extremities. Or improved balance by lowering center of gravity. Depending on who you ask or follow. But what they don't explain is how the alleged air sacs left even less space around the skeleton for muscles and tendon system to wave about with that long neck and head. Unless of course sauropods didn't give two monkeys about O2 because they breathed helium.
Very recently Professor Bill Sellers of Manchester University and his team checked previous biomechanical models on T-rex and sadly they concluded the poor creature was limited to slow walking and couldn't run due to strength of its leg bones. Well - there a good scene for Jurassic World 7 (or whatever sequel we're at) : "ROOAAARR... "oh my god, its T-Rex, run!"... (5 seconds) stomp... (5 seconds) ... stomp....". Well, it did run, it did chase a prey. Just not in 1g.
In all seriousness though - I love debunking blogs/videos as much as I love my "lone gunmen of science" theorists - so I'll gladly read anything that says otherwise, if you have links - I've read Dr. "I will delete any comment that doesn't agree with me" Francis' blog you guys posted, complete with all the comments, with pleasure, even though he doesn't convince me even one bit.
Angilion said:
Aww... yay. Your maths may be just as out of whack as your physics.
No, silly, it doesn't take three massive planets to create one Earth.Anyway, there are multiple proposed mechanisms of Earth expansion. Once again - I'm just going to list some of them, in random order and you can pick your google fight with the authors directly if you want - cause that's exactly what's coming. Oh, and do keep in mind that not all of them agree on how much lighter and smaller prehistoric Earth was:
- Earth mass gain through input of magnetically charged electrons and protons from the sun via the Earth's magnetosphere, polar auroral zones and electrical storms and transfer by conduction into magnetic core-mantle. (Eichler, 2011; Maxlow, 2014)
- Earth mass gain based on the model for interaction and absorption of neutrino radiation (Prof. Konstantin Meyl, Computer and Electrical Engineering)
- Earth mass gain based on continuous transition of background energy to mass in accordance with the energy/mass equivalence equation (De Pretto, 1903/Einstein 1905) - the continuous mass accumulation within the earth's core builds up internal pressure which is released periodically as an earthquake or volcanic eruption with measurable local expansions across earthquake fault lines or volcanic lava (Simon Brink - Environmental Engineer).
- Earth mass gain based on a concept of aether (many in the past, most recently Prof. Giancarlo Scalera, geophysicist)
- Earth mass gain based on theory of Earth being originally a gas giant converted to chthonian planet by sun with rapid expansion since 180 millions of years ago due to force balance between cracked rigid mantle and previously highly compressed interior (Jan Mestan, geophysicist)
- Earth mass gain based on nucleons of atoms entering through South Pole and combining with G1 particles (de Hilster Particle Model) to recombine into atoms within the earth (Bob De Hilster, electrical scientist, very unorthodox and fringe idea in it's own right)
and finally (drumroll)
- Earth mass gain through "inflalling debris" and meteoric activity. Oh - that's right. Not my favourite "favourite" explanation, because it doesn't go well with other, more elegant concepts and not the geologists' favourite - but it's, excuse the pun - the most "down to Earth" explanation.
We diss theories in a blasé fashion because, perhaps, sometimes we lack the real sense of scale of things. So - for example when Angilion wrote (I quote) "the last few dozen million years", belittling the time frame as a "few dozen". Then adding a "million". But, shouldn't we instead see it as a literal "forever"? A continuous process from anywhere before the Cambrian explosion 540 millions of years ago and maybe 65 million, give or take 10 or 20 million years ago. You know how the oldest human "writing" Jiahu symbols have about 8,000 years? Then, it's like - a half a billion years before that with maybe 60 million years margin of error, lasting for half a billion years. Or - you know how the first hominid creature appeared on Earth about "a half dozen" millions years ago? So that's like - (counts on fingers) - still half a billion years ago, give or take 60 million years, lasting for about half a billion years. It's that kind of scale. So even without all the neutrino, ionisation, aether stuff - just take those few hundred thousand metric tones of the usual outer space crap NASA accounts for a year plus whatever didn't hit our moon (look at that fella!) in larger chunks and that's already massive number.
Yet, even by NASA's "statistically insignificant" fraction of a mm a year debris accumulation, over 500-600 million years that's at least the thickness of the entire oceanic crust? Isn't it?
People will often believe in incredible things during such timescales. They'll believe that entire oceans appeared. A single landmass split into multiple continents, and drifted all over the planet. Several times. Lands and basins got boinked up and shifted all over the place to such a degree that ocean living plesiosaurs are found some 1000km inside Australian "interior" at 160 meters above sea level. Several times. Large objects fell from space and killed nearly all the inhabitants of the planet. Several times. Fires, of unimaginable proportions, swept the planet annihilating most of its vegetation. Several times. Entire planet gone through ice ages and global warmings. Several times. But tell them - Earth has attracted and accumulated a lot of **** during that time - and they go - "nah, that's crazy".
Angilion said:
Oh but no. All that because YOU don't understand how larger animals moved and you asked in GD. You are the OP. (drops the mic, stretches heavy arms of 132kg body with thin skeleton of 67kg person inside) : How about another socially distanced hug?
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Soldato
The earth does occasionally gain more mass. Only a tiny fraction of its existing mass and those events tend to **** everything up 
E: All these word walls are too dense for me right now. It's like the density is going up somehow? That's new physics right there, gents
E: All these word walls are too dense for me right now. It's like the density is going up somehow? That's new physics right there, gents
Soldato
Flying wasn't a problem for dinosaurs as gravity wasn't invented until 1687.
Soldato
There is no need for us to go around in circles gents. Smaller prehistoric Earth means smaller planet. As in smaller mass. I know you both understood me well the first time around, any chance you just raise smoke and dance with mirrors to cover up your previous "physics" faux pass of "larger Earth would have less gravity"? No need. I don't hold it against you, ok?
Thank you for clarifying. I believe we did both understand, but clarification is always good. You seem to be missing that a smaller radius means higher gravitational pull at the surface, but I guess less mass will reduce that.
I assume by rotating at the same speed, you mean angular momentum, so the same day length? In which case, gravity would be higher, since objects on the surface would be travelling slower. Since this is a tech forum, think of a fan. The edge of the blade is travelling much faster than the part closer to the centre. It's angular momentum is the same (they both complete a full circle in the same time, obviously), but it's speed is lower. You'd have to have a shorter day with a smaller earth, just to match the same effect that we currently have from centripetal/fugal forces. Even faster still for it to provide a reduction in gravity felt. It has a tiny effect anyway, so really isn't worth trying to pursue.
So - let's not overcomplicate things - the ideas are very, very simple, I understood them after first read - but perhaps I'm just not explaining them very well. Also keep it mind these are not MY ideas, they were not invented by ME - these are theories proposed by various scientists, for long decades, with volume of work and titles to their name, and many of them spent their entire careers promoting these ideas. If anything it may be the early stages of what "quantum physics" did to classical newtonian, einsteinian physics - but for geology and palaeontology. If you will - everybody still nods to the Plate Tectonics, but slowly more and more scientists realise there are more holes in that theory than explanations:
1. The "Prehistoric Earth of dinos was smaller and lighter" thing. This theory is officially called Expansion Tectonics
What does this theory fix? From what I understand - apparently everything except for "where did the mass of todays Earth come from" (more about it later) and "what about density of air" (more about it one quote below) outrage on a OCUK subforum.
Age of theory? Old, almost as old as Plate Tectonics. It's been out there forever. Actually there was entire stream of German geologists postulating it in early twenties and thirties of 20th century, but due to the obvious "dude, wrong place, wrong time" reasons their volume of work weren't even translated for review up until sixties and peers re-approached their work only a few decades later.
Proof? Apparently many. For starters - obviously - biomechanics of palaeontology - it explains how dinos moved, their flight, why their bones aren't much bigger for the mass, why all animals and vegetation were bigger too.
It also "fixes" current large scale issues with plate tectonics theory - why continents that moved away from Pangea can be "matched" to both ends, while according to PT theory they could separate and move away from one end. Or since the tectonics pulled away Pangea apart to create Atlantic Ocean, why are there tectonic expansions around the Pacific rim (as in Pacific, if anything, should have shrunk to give way to Atlantic). The unaccounted up/down shifts (eg. eastern coast of North America) as proven by fossils and so on.
It matches well with other peer reviewed studies that couldn't find supporting for PT (like the "precambrian pole wandering") and unlike PT - it doesn't create necessity for some unsupported and unexplained by evidence shifts and movements, like for India to "crash" into today's Eurasia to create the Himalayas, yet Eurasia and India share the same fossils of many species from dinos to fungus gnats from the period when there was meant to be a massive volume of water between them.
It provides elegant solution to why all the oceanic floors are "young" - as in - only 100-250 mil years old vs 4 billion old continental crust and why we never found any oceanic sedimentation from before Palaeozoic and so on.
According to some - the same mechanism may be even responsible for expansion of other planets, like Mercury, equatorial rift on Mars or even NASA backtracking on their shrinking moon claim and admitting that our moon, geologically dead as Elvis - has undergone "recent" expansion (the "grabens") (I don't particularly like this particular part of speculation, but for transparency etc here it is..).
Essentially, as with all such work - you would have to give it a few hours of your time - read some papers, visit some sites, watch some videos, listen to a few badly amplified lectures, etc. You then have to go through all the debunking videos and sites as well, for balance. But it's a must.
Names, videos and papers to google: Prof. Samuel Carey and Dr. James Maxlow (geologists), John B. Eichler (mathematician and physicist, nuclear background), Giancarlo Scalera (geophysicist), Dr. Hugh G. Owen (geologist) , Cliff Ollier (geologist, geomorphologist), Karl-Heinz Jacob (chemist), Jan Koziar (geologist), Prof. Stefan Cwojdziński (geoscientist), Carl Strutinski (geologist), Stephen W. Hurrell (design engineer), William C. Erickson (physicist), Dr. Zahid A. Khan (geologist), Prof. Karl W. Luckert (philosophy), Prof. Wenbin Shen (geophysicist) and Sung-Ho Na (geoligist), Zahid Ali Khan and Ram Chandra Tewar (geologists)
2. Prehistoric Earth had different tilt.
Almost all the branches studying dinosaurs think dinos lived in the environment that was very warm (as Unseul mentioned before) and very stable. Dinos almost certainly never seen snow and probably the planet had no seasons to speak of, according to people who study prehistoric climates. So - there is one simple explanation - Earth tilt was still 0 or close to 0 deg. - et voila.
This view may be simply too narrow guys? Once again - you are describing density of today's atmosphere - if today's Earth suddenly had smaller gravity that could become a big deal to our current atmosphere ( for humans ).
Scientists from speculative paleo*-branches think they have a good picture of prehistoric climate, although in reality we probably know very little about the exact environment, size, mass, density, composition of atmosphere 64-300 millions of years ago - we definitely have no clue what requirements those animals had for "air". But even according to the current official narration dinos throughout most of their hegemony on Earth actually had less oxygen to breathe than we do now - up to a 1/4 less.
Although the levels of O2 are believed to be as high as 26% by the end of Permian (the theoretical Permian oxygen gigantism mentioned by everyone before in this thread), they were down to 15%-17% in Triassic, compared to about 21% now. If 5% extra was responsible for gigantism, did they shrink after it dropped to 16%? ? No. And btw - 15-17% corresponds exactly to something like 2000-3000 meters now, but I'm not going to count it as a point for "my" theory, because a) I don't think the science of estimating prehistoric atmosphere is sound enough either way b) the same people believe O2 fluctuated rapidly between as low as 17% and as high as 30% throughout Cretaceous and Jurassic and I don't think it actually particularly mattered to flora and fauna inhabiting Earth back.
More oxygen, less oxygen in the "air" - the biggest animals inhabiting our planet clearly had no issues living with any variation of it and that's regardless of the whole "smaller Earth with less gravity" theory. We find their fossils literally everywhere across entire Pangea and post-Pangea landmasses - from todays Antarctica all the way to Siberia, so regardless of the "air", climates, temps, shapes and sizes of continents back then - all of them, including biggest sauropods lived through the entire prehistoric "always", everywhere and all the way to the end of it all. And that's again - according to the official climate-palaeontology-thingymagiggy-science data, not the "smaller earth" fringe. Bottom line - speculating about them getting lightheaded from air density may just fall in the "what if they breathed in methane, breathed out ignited napalm and couldn't feel temperatures at all through their dragon skin" territory.
I've genuinely never read anyone say they knew why or how dinosaurs grew so large and survived so large. We got used to seeing Hollywood CGI of them walking and running and based on that treat it as if it were normal but from what I understand from the start to this day palaeontologists still agree it's a bit of a mystery to everyone studying them.
Bird bones don't really explain it or fix the problem - birds bodies are small and light, large dino bodies were just too heavy for the bones we find. 40 metre long, 80 tons of meat on four short legs in the centre and presumably the animal wouldn't knock itself dead if it fell, could stand up afterwards, could climb hills etc. In 1g that's either super light muscle tissue or super strong material for bones, definitely not the biotech we understand. One of the evidence presented for birds being descendants of dinos is (according to palaeontology) speculative presence of "airbags" - air sacs - in large sauropods and few other *sauruses. Air sacs were connected to lungs and were used for cooling. Or increased respiratory ability for extremities. Or improved balance by lowering center of gravity. Depending on who you ask or follow. But what they don't explain is how the alleged air sacs left even less space around the skeleton for muscles and tendon system to wave about with that long neck and head. Unless of course sauropods didn't give two monkeys about O2 because they breathed helium.
Very recently Professor Bill Sellers of Manchester University and his team checked previous biomechanical models on T-rex and sadly they concluded the poor creature was limited to slow walking and couldn't run due to strength of its leg bones. Well - there a good scene for Jurassic World 7 (or whatever sequel we're at) : "ROOAAARR... "oh my god, its T-Rex, run!"... (5 seconds) stomp... (5 seconds) ... stomp...."
In all seriousness though - I love debunking blogs/videos as much as I love my "lone gunmen of science" theorists - so I'll gladly read anything that says otherwise, if you have links - I've read Dr. "I will delete any comment that doesn't agree with me" Francis' blog you guys posted, complete with all the comments, with pleasure, even though he doesn't convince me even one bit.
Aww... yay. Your maths may be just as out of whack as your physics. . No, silly, it doesn't take three massive planets to create one Earth.
Anyway, there are multiple proposed mechanisms of Earth expansion. Once again - I'm just going to list some of them, in random order and you can pick your google fight with the authors directly if you want - cause that's exactly what's coming. Oh, and do keep in mind that not all of them agree on how much lighter and smaller prehistoric Earth was:
- Earth mass gain through input of magnetically charged electrons and protons from the sun via the Earth's magnetosphere, polar auroral zones and electrical storms and transfer by conduction into magnetic core-mantle. (Eichler, 2011; Maxlow, 2014)
- Earth mass gain based on the model for interaction and absorption of neutrino radiation (Prof. Konstantin Meyl, Computer and Electrical Engineering)
- Earth mass gain based on continuous transition of background energy to mass in accordance with the energy/mass equivalence equation (De Pretto, 1903/Einstein 1905) - the continuous mass accumulation within the earth's core builds up internal pressure which is released periodically as an earthquake or volcanic eruption with measurable local expansions across earthquake fault lines or volcanic lava (Simon Brink - Environmental Engineer).
- Earth mass gain based on a concept of aether (many in the past, most recently Prof. Giancarlo Scalera, geophysicist)
- Earth mass gain based on theory of Earth being originally a gas giant converted to chthonian planet by sun with rapid expansion since 180 millions of years ago due to force balance between cracked rigid mantle and previously highly compressed interior (Jan Mestan, geophysicist)
- Earth mass gain based on nucleons of atoms entering through South Pole and combining with G1 particles (de Hilster Particle Model) to recombine into atoms within the earth (Bob De Hilster, electrical scientist, very unorthodox and fringe idea in it's own right)
and finally (drumroll)
- Earth mass gain through "inflalling debris" and meteoric activity. Oh - that's right. Not my favourite "favourite" explanation, because it doesn't go well with other, more elegant concepts and not the geologists' favourite - but it's, excuse the pun - the most "down to Earth" explanation.
We diss theories in a blasé fashion because, perhaps, sometimes we lack the real sense of scale of things. So - for example when Angilion wrote (I quote) "the last few dozen million years", belittling the time frame as a "few dozen". Then adding a "million". But, shouldn't we instead see it as a literal "forever"? A continuous process from anywhere before the Cambrian explosion 540 millions of years ago and maybe 65 million, give or take 10 or 20 million years ago. You know how the oldest human "writing" Jiahu symbols have about 8,000 years? Then, it's like - a half a billion years before that with maybe 60 million years margin of error, lasting for half a billion years. Or - you know how the first hominid creature appeared on Earth about "a half dozen" millions years ago? So that's like - (counts on fingers) - still half a billion years ago, give or take 60 million years, lasting for about half a billion years. It's that kind of scale. So even without all the neutrino, ionisation, aether stuff - just take those few hundred thousand metric tones of the usual outer space crap NASA accounts for a year plus whatever didn't hit our moon (look at that fella!) in larger chunks and that's already massive number.
Yet, even by NASA's "statistically insignificant" fraction of a mm a year debris accumulation, over 500-600 million years that's at least the thickness of the entire oceanic crust? Isn't it?
People will often believe in incredible speculations to happened during such timescales. They'll believe that entire oceans appeared. A single landmass split into multiple continents, and drifted all over the planet. Several times. Lands and basins got boinked up and shifted all over the place to such a degree that ocean living plesiosaurs are found some 1000km inside Australian "interior" at 160 meters above sea level. Several times. Large objects fell from space and killed nearly all the inhabitants of the planet. Several times. Fires, of unimaginable proportions, swept the planet annihilating most of its vegetation. Several times. Entire planet gone through ice ages and global warmings. Several times. But tell them - Earth has attracted and accumulated a lot of **** during that time - and they go - "nah, that's crazy".
Oh but no. All that because YOU don't understand how larger animals moved and you asked in GD. You are the OP. (drops the mic, stretches heavy arms of 132kg body with thin skeleton of 67kg person inside): How about another socially distanced hug?
Sorry for the large chunk approached in one go here. Yes, recently they concluded t-rex couldn't run quickly, I'd already mentioned that. So our previous thoughts were wrong. Which is great, but as pointed out, there's also other evidence to suggest that it was primarily a scavenger, poor eyesight and good olfactory abilities points to this also. Don't need to run fast if your food is dead already.
Plenty of people do seem to think bird bones and airsacks solve the problem. Nice resource on many of the ideas are here: https://collections.plos.org/sauropod-gigantism
There was a big old extinction event (Permian triassic) coinciding with this low oxygen period. However, this isn't when the big dinosaurs existed. So it's not particularly relevant is it? They came later as oxygen levels increased. As you've said, we're talking about a big old timeframe, lets try and avoid conflating it all together. We can measure oxygen %age levels, but if we had less gravity, then it's all less dense anyway, and then we really do have an issue. Oxygen levels were going up again in the Jurassic and later stages (which is when these big guys came along)
You've listed theorectical ideas, that use unknown mechanisms, to add mass.
As for how much stuff is added to earth through dust/asteroids etc, it's about 40,000 tons a year, not hundreds of thousands. Over 75 million years, that's 3000000000000 tons.
Which sounds good, until you see the earth is 6000000000000000000000. Which is apparently 0.00000005%. Not really enough to have a significant effect on the gravity, or size of the planet. Figures from here: https://astronomy.com/magazine/ask-astro/2014/07/space-debris
I've skipped over some of the plate tectonics claims, I'm not sure I need to try and defend them.
Soldato
How did they manage to jump so high and take flight? The same way we achieve it to this day: Tampons & Red Bull.
There is no need for us to go around in circles gents. Smaller prehistoric Earth means smaller planet. As in smaller mass. I know you both understood me well the first time around, any chance you just raise smoke and dance with mirrors to cover up your previous "physics" faux pass of "larger Earth would have less gravity"? No need. I don't hold it against you, ok?
So you're being an ******** because your argument is nonsense and you have to change what you're saying to even pretend to make it fit. Size and mass are not the same thing and you saying that they are doesn't make it so. Given that there's no evidence that Earth merged with at least 3 other planets of similar mass in the last few dozen million years (which would be necessary for an large increase in size and a 250% increase in gravity on the surface), a claim that Earth was much smaller back then doesn't even imply that it was much less massive too, let alone state it.
If you care to try again without being an ********, I'll read your reply.
Soldato
I'm sorry Unseul, but that wouldn't be the case. Not for a planet half the size and half the mass. And it's not 75 million years. We won't get to finish this discussion due to Angilion's abusive character, but the target number this was going towards was increase in radius by ~22mm per every completed orbit around the sun.
I'm sorry Angilion, but no - I don't care to try again. Not with your childish behaviour. I've been very reasonable despite your more and more aggressive ranting and I've spent considerable amount of time trying to introduce you to a valid, discussed, published scientific hypothesis/theory, call it what you will, including quite a solid outline, sources, bibliography and authors. I'm sorry if it doesn't agree with your strange understanding of physics (and rather strange maths), but I'm afraid it's proposed and run by people way above your paygrade, with all due respect.
One more thing. Back in 2016 you were awarded the title of Man of Honour for "managing to remain consistently polite". How little we knew ya. Substance abuse on Satuday night or not - your habit of bulling interlocutors to submission with obscenities is unbecoming to the title you carry. I offer you a hug and you repeatedly vomit expletives towards me Angilion? Seriously? What a forum member. What a man.
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You don't get to use my refusal to reply to your rudeness as an excuse for bowing out due to a lack of evidence or argument. You're trying it but (unlike pterosaurs) it won't fly. And no, refusing to reply to rudeness is not abusive. That won't fly either.
Soldato
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If a large herd of really big dinosaurs ran in one direction, would the earth act like a giant treadmill?
Soldato
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Every time they word wall, the world gets heavier as more data is being added to the internet hd's
https://www.physicscentral.com/experiment/askaphysicist/physics-answer.cfm?uid=20080512101012
Soldato
Sorry v0n, not that easy. Half the size (I assume half the radius here), half the mass.
A planet half the mass, and half the radius of earth, is going to have DOUBLE the surface gravity.
It's quite a simple equation to work it out in terms of gravity relative to earth. You take your planet's mass as a proportion of earth's (so in our case 0.5), and your planet's radius as a proportion to earth's (so 0.5 again). You divide the proportional mass, by the proportional radius squared.
That gives you double the relative gravity.
Here: https://en.wikipedia.org/wiki/Surface_gravity
And of course, smaller radius, but same rate of spin, is a lower speed on the surface, so the spin of the earth would have less effect on the gravitational pull than it currently does (which is minuscule anyway).
Well, you had titanosaurs at the end of the Cretaceous. So 100-66 million years ago. Still, we're needing to find a lot of mass (I've already given you the sort of numbers we're talking about).
I'm sure there must be an ignore function on this forum? Feel free to use it on him if you must.
Btw, you need to reduce your mass a lot more (as I've shown). If you want half the gravity you currently have, you need the earth to have weighed only 1/8th of it's current mass.
I'm actually fairly sure, given the changes in mass required, and assuming the method is ongoing, we'd likely be able to measure the change in mass on earth, if there was a mechanism adding so much mass to the planet so quickly. Even more intriguing is what the hell the earth was doing in it's previous 4.5bn years of existance... it must have been absolutely insignificant...
Don
OK, physics graduate here.
v0n you are confusing gravity to angular momentum. Changing the rotational speed of a body has no effect on it's gravitational pull which entirely a function of mass:
f = G x (m1 X m2)/r^2 Where G is the gravitational constant. Notice how there is no speed or angular speed values in there.
Calculating it out, the force on a 100kg man at the surface is:
f = 6.67x10^-11 x (100kg X 5.9x10^24kg)/6378000M^2 = 967.4N
As for the speed of the planet rotating causing a large shift in the perceived gravitational pull at the surface. Let's calculate it.
f = (mv^2)/r where v = d/t
v = 40,000,000M / 86164s = 464.2 Ms^-1
Assuming a 100kg person
f = (100 x 464.2^2)/6,378,000M = 3.4N
So, the rotational speed of the earth causes a 0.35% change in the felt gravitational force at the surface.
Let's more than quadruple the rotational speed of the earth:
v = 40,000,000M / 20000s = 2000 Ms^-1
f = (100 x 2000^2)/6,378,000M = 62.7N which is a 6.5% change in the felt gravitational force.
v0n you are confusing gravity to angular momentum. Changing the rotational speed of a body has no effect on it's gravitational pull which entirely a function of mass:
f = G x (m1 X m2)/r^2 Where G is the gravitational constant. Notice how there is no speed or angular speed values in there.
Calculating it out, the force on a 100kg man at the surface is:
f = 6.67x10^-11 x (100kg X 5.9x10^24kg)/6378000M^2 = 967.4N
As for the speed of the planet rotating causing a large shift in the perceived gravitational pull at the surface. Let's calculate it.
f = (mv^2)/r where v = d/t
v = 40,000,000M / 86164s = 464.2 Ms^-1
Assuming a 100kg person
f = (100 x 464.2^2)/6,378,000M = 3.4N
So, the rotational speed of the earth causes a 0.35% change in the felt gravitational force at the surface.
Let's more than quadruple the rotational speed of the earth:
v = 40,000,000M / 20000s = 2000 Ms^-1
f = (100 x 2000^2)/6,378,000M = 62.7N which is a 6.5% change in the felt gravitational force.
I try to keep an open mind and there are a lot of unanswered questions but when it comes to gravity the changes needed either in mass, size or rotation period/speed are just so big it would throw everything else we know out completely if they had occurred at the kind of magnitude required in this context that I struggle to see it as credible.