Comments by "Andy Hughes" (@andyhughes1776) on "PBS Eons" channel.

No scientists ever explain why prehistoric animals were so big and why no modern land animals could match their size. What mechanism(s) limit the size of today's land animals? Here's my hypothesis (no one told me this - I came up with it myself): The reason why prehistoric animals could get so big was because the earth was smaller back then - less mass means less gravity. Less gravity allows creatures to get bigger. So how did the earth became bigger? The asteroid(s) that hit earth and killed the dinosaurs added to the size and mass of the earth, thereby increasing its gravity. Ever since then, no animals could get as big as dinosaurs except sea creatures (such as blue whales) because the buoyancy of water allows them to grow that big. Any scientists out there want to find evidence for my hypothesis? I would start with estimating the size(s) and number of asteroids that hit earth back then. There should still be remnants of craters caused by these impacts. Then calculate how much mass they would add to earth's. Also, calculate the maximum size an animal can get with today's gravity and compare that to a slightly lower gravity environment (by subtracting the mass of the asteroids that hit earth). If the maximum size in the lower gravity environment matches the size of the biggest dinosaur, then that is evidence that the earth was probably slightly smaller back then.
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@richardblazer8070 How do you know that earth has remained rather consistent volume since life first arrived? What evidence do you have to claim that? There were many more asteroids that hit earth than just one that killed the dinosaurs - look at all the craters on the moon. In fact, because earth is bigger than the moon, chances are that it got hit more often than the moon (bigger target). Where did all that extra mass go once they hit earth? I never heard that dinosaurs had hollow bones - flying ones did but not all dinosaurs. Also, your theory cannot explain the following: 1) Fluid dynamics calculations show that long neck dinosaurs (up to 50 ft or higher) such as the Brontosaurus cannot get enough blood to their head fast enough to prevent them from blacking out everytime they raise their head....unless their heart was so big it takes up half of their body cavity (which we know is not true). But even if they do have such a large heart, the pressure will cause them to have heart attacks and/or their blood vessels to burst and cause a stroke. As a result, some scientists suggested that maybe long neck dinosaurs have two hearts - the second one is smaller and located half way up their neck. The problem with this theory is that nowhere in their neck bones that showed a cavity for such a secondary heart. So, the only logical explanation of how blood could get to the head of such a large animal is that earth's gravity was weaker back then. And the only way that could happen was that earth was slightly smaller back then. 2) Some Pterosaurs were the size of today's Giraffe (18 ft tall). Even with hollow bones, aeronautical engineers calculated that they won't be able to fly due to their weight and not enough chest strength. The largest Pterosaurs are estimated to weigh around 550 pounds. A similar size aircraft to the Pterosaur is the Light Sport Aircraft, which weighs 1,320 pounds and it requires around 100 horsepower to lift off the ground. So, Pterosaurs must generate around 50 horsepower to get off the ground. As a result, it is believed that these large Pterosaurs flew by jumping off cliffs but fossils of these flying dinosaurs were found in areas not known to have high cliffs during the time they lived. Again, this points to the earth having less gravity, which would have allowed these heavy Pterosaurs to take off and fly under their own power. Science is not static - if a hypothesis could better explain a phenomenon, then it must be explored further to find evidence for such.....and if found, the old theory must be revised or discarded. But you just dismiss it outright even though the old theory cannot explain the two points above. That is not scientific, is it?
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@richardblazer8070 LoL.. you're the first person I ever heard labeling it a "meteor" instead of "asteroid"....to downplay its size - I know! In any case, I also know for a fact based on the countless craters on the moon that earth was also hit with countless rocks, not just with one tiny meteor as you implied. And these space rocks (regardless of size!) contain mostly Iron and other heavy metals. In other words, high density substance that produce more gravity than, say, loosely packed sand. Therefore, it doesn't take that many of these things to increase earth's mass, hence gravity. A SLIGHT increase in mass of the earth is enough to prevent today's land animals from growing to the size of dinosaurs. You couldn't provide any arguments against my two previous points about blood to the head of Brontosauris and flight of Pterosaurs. And you couldn't provide any evidence for the one argument you claimed.
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@richardblazer8070 How many times have I told you that it was NOT a meteor and not just one ASTEROID. By definition, a meteor is a space rock no bigger than a meter in diameter. The rock that destroyed the dinosaurs was 6 miles wide (you said that yourself) therefore, it is classified as an ASTEROID, not a meteor.. It was HUNDREDS OF THOUSANDS of iron rocks of many sizes that hit earth.....just like what hit the moon. Look at the moon. Does it have just one crater? Nope, the moon has THOUSANDS and so does the earth, which is proof that the earth accumulated mass throughout its history. You just can't see many craters on earth now because of weathering (rain, wind, vegetation growth, etc) that erased them. STOP saying that only one meteor hits earth! I provided proof - thousands of craters on the moon by rocks of MANY sizes, INCLUDING asteroids. A 6 mile wide rock is called an ASTEROID, not a meteor! Again, by definition, a meteor is a SMALL rock no bigger than a meter in diameter. Ok, now you provide evidence that only one small rock hit earth throughout its history.
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@richardblazer8070 No scientists ever came up with my hypothesis to even dispute it. Please cite which scientists and studies dispute my hypothesis.
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@richardblazer8070 That is exactly how science works! I bet you think that science is accepting what some authority with a fancy title said forever more. That's religion, not science. Carl Sagan said, "There is no authority in science - experts at best." And these experts must provide evidence for their claims too - they can't use their title as proof ("I have a PhD, therefore I am correct" - nope!) Science is about CONTINUOUSLY questioning, testing, and revising our theories to better explain the phenomena observed. Einstein's theories are still tested and retested today even though they are well established for a Century now. I deliberately used the word "hypothesis" instead of "theory" because my proposed explanation is just that - an UNTESTED PROPOSAL. Google the definition of a hypothesis and see for yourself: https://www.google.com/search?q=hypothesis+meaning&oq=hypothesis&aqs=chrome.1.69i57j0i67i433l2j0i433l2.4141j0j7&client=ms-android-att-us-revc&sourceid=chrome-mobile&ie=UTF-8 I already suggested how we could test out my hypothesis (estimate the mass of all rocks that bombarded earth throughout its history. Then subtract that mass from today's earth and see how much smaller earth was before a that mass bombarded it). Again, science is about asking questions, proposing a possible explanation (hypothesis), testing your proposal, then formulate a theory to be peer-reviewed to verify. And even after acceptance, if a new proposal better explains the phenomena in question, then it should be explored further. I want my hypothesis (proposed explanation) to be explored further. I want evidence!
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I once read that fluid dynamics calculations had shown that it is not possible for blood to get to these dinosaurs's head because their neck is too long. One suggestion was that they must have had 2 hearts - one main heart in their body and another smaller one half way up their neck. But the fossil records indicated no such organ in their neck. So how could they kept from passing out everytime they raise their head high? My hypothesis: earth used to be smaller hence had less gravity back then. This could also explain how pterosaurs the size of giraffes could fly. Ok....so how did earth get bigger subsequently? The asteroid(s) that hit earth and killed the dinosaurs also added to earth's mass, which increased the strength of its gravity. So ever since then, no land animals could grow as big as dinosaurs (because the stronger gravity due to the increased size of the earth prevented them). I am surprised no one had proposed this hypothesis. You heard it from me first!😁
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@AndrewTBP Prove it! Even if you could, you must also explain how dinosaurs the size of today's Giraffe could fly. One simple explanation that allows both to occur is lower gravity - Occam's Razor!
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Dinosaurs got so big because: The earth used to be smaller back then. Smaller size meant less mass. Less mass resulted in less gravity. Less gravity allowed creatures to grow big without being crushed under their own weight. Evidence? The asteroid that killed the dinosaurs was so big that it left a crater (still visible from space today) 93 miles wide and 12 miles deep. Where did all that mass go after it hit earth? Why, it became part of the earth, of course....which then added to the mass of and increased the gravity of earth. And it is not the only mass that hit earth. There were smaller, but still sizeable, craters on earth that indicate other asteroids had hit earth, which contributed to increasing its mass. So, ever since then, land animals on earth could not get as big as dinosaurs. This could explain how pterosaurs the size of giraffes could fly. And how Brontosaurus and other super large dinosaurs could get blood to their head when their neck was too long. Fluid dynamics dictate how far a fluid could be pumped with a heart in 1G and it doesn't add up......unless in weaker gravity. I am surprised no one else came up with this explanation. I want my Nobel Prize!😁
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@AgroAcro So ONLY ONE asteroid ever hit the earth? Nice try, but look at the surface of the moon to see how many craters there are. Earth was likely hit EVEN MORE simply because it's bigger than the moon (bigger target). My theory stands.
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@AgroAcro Again, not just one rock hit earth but thousands or even hundreds of thousands or more - look at how many craters are on the moon! It looks like 65 million years ago, earth went through an asteroid shower. I suspect that these rocks came from the asteroid belt where a planet used to be but collided with another comparable sized body and broke into a million pieces. Some of those pieces were thrown so far away that they actually crossed earth's orbit and collided with earth. It's my theory worth investigating with real-world data. How? First, count how many craters are on the moon and what size rocks caused them. Then, multiply that by 4 because earth is roughly 4 times the size of the moon. Ok, now estimate the total mass of all those rocks that hit earth and subtract it from today's earth to come up with the approximate size of earth before those rocks hit.
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@AgroAcro Understand also that space rocks of all sizes continued to bombard earth for 65 million years after the dinosaurs died out. That is a long time to be exposed to collisions so yeah, there could be enough to significantly add to earth's mass. For all we know, an asteroid half the size of the moon could've hit earth - we need to look for evidence of that. Bottom line is since the demise of the dinosaurs, there has never been land animals as big. Why? No, not the availability of food because that does not explain how brontosaurus don't get strokes or how a pterosaur the size of today's giraffe could fly. The only logical explanation is that earth used to be SLIGHTLY smaller with less gravity, which allowed dinosaurs to be so big.
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I have a hypothesis to explain how such a large animal could fly under its own power. My hypothesis also explains why prehistoric animals were so big but no modern land animals could reach their size. Here it is: The reason why prehistoric animals could reach such large sizes was because the earth was smaller back then. Smaller earth meant less mass. Less mass resulted in less gravity. Less gravity allowed creatures to grow bigger....and some to fly (need less energy to get airborne). Ok, so how did the earth grew in size then? When the asteroid(s) hit earth and killed the dinosaurs, they also added to earth's mass. Ever since then, no animals could be as big as dinosaurs due to the stronger gravity. No one told me this. I came up with this hypothesis myself. How else could anyone explain why land animals today cannot be that big.
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@ankylosaurussupremacy Not only one asteroid hit earth throughout its history - look at the moon. If anything, the earth got hit MANY MORE times than the moon simply because it is bigger (bigger target more likely to get hit). Someone needs to look into this with data, not opinion. I just proposed a hypothesis for further study, that's all.
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No scientists ever explained how prehistoric animals could be so big yet none of today's land animals could match their size. There must be some condition that limit the size of today's animals. What is it? Here's my hypothesis: The reason why prehistoric animals could be so big was because the earth was smaller back then. Smaller earth meant less mass. Less mass resulted in less gravity. Less gravity means animals could grow big without being crushed by their own weight. Ok....so how did the earth become bigger? The asteroid(s) that killed the dinosaurs also added to earth's mass and increased its gravity. So ever since then, land animals could not grow as big as dinosaurs. Sea creatures such as the blue whales could still grow big because of the buoyancy of the ocean. I am surprised no one had proposed this hypothesis. It could explain how pterosaurs the size of giraffes could fly or how a brontosaurus's heart could pump enough blood to its head when its neck was too long.
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@raptorzilla0710 Please cite the study that proved so.
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@AgroAcro Not just 1 asteroid hit earth - look at all the craters on the surface of the moon.
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@AgroAcro So, how come there are no land animals today as big as dinosaurs? (why no air sacked bones today?)
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@AgroAcro So why not in large non-flying animals today like the dinosaurs back then? What condition(s) stopped that ever since the dinosaurs died out?
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@AgroAcro LoL, are you using your brain to think? When the asteroid(s) hit earth 65 million years ago, it WIPED OUT ALL DINOSAURS in a short period of time. That was immediate. Those who didn't die right away via the impact, died soon after due to fallout and lack of food. Then, perhaps millions of asteroids continued to bombard earth (look at how many craters on the moon as evidence), which added to its mass. That prevented subsequent land animals from evolving into such large size. Sure, it took millions of years for that. But the strong gravity prevented any creatures from ever becoming that big again.
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