Spring in the Northern Hemisphere; Fall in the Southern Hemisphere.
The Northern Hemisphere does account for 68% of overall land area. https://www.worldatlas.com/articles/which-hemisphere-has-the...
Did it at the K-T boundary?
An asteroid killed dinosaurs in spring, which might explain why mammals survived
51–60 of 87 posts
Re: An asteroid killed dinosaurs in spring, which might explain why mammals survived
#52> Three-dimensional rendering of the partial paddlefish fossil, with googly eyes added for reference.
I'm glad to see even serious scientists can have fun sometimes.
Re: An asteroid killed dinosaurs in spring, which might explain why mammals survived
#53Only half of the Earth would be destroyed in that manner due to Earth Northern hemisphere and Southern hemisphere having opposite seasons. Go back to the drawing board.
Most of the land mass is in the northern hemisphere, even back then.
Re: An asteroid killed dinosaurs in spring, which might explain why mammals survived
#54Spring in the Northern Hemisphere; Fall in the Southern Hemisphere.
And perpetually tropical in the tropics
Re: An asteroid killed dinosaurs in spring, which might explain why mammals survived
#55Earlier quoted context omitted.
Can't believe the downvoting. There's several major issues with the current dinosaur theory RN. Four areas of scientific incongruities regarding these animals’ large size are 1) insufficient muscle strength, 2) insufficient bone strength, 3) unacceptably high blood pressure within the tallest dinosaurs, and 4) the paradox of pterosaurs having grossly insufficient power to fly in atmospheric conditions similar to the…
People forget there were mammals compare to or were bigger elephants in our recent past. The giant ground sloth - https://en.wikipedia.org/wiki/Megatherium Mastodons - https://en.wikipedia.org/wiki/Mastodon Wandering Albatross - https://www.thehindu.com/sci-tech/energy-and-environment/ant... Giant armadillos - https://en.wikipedia.org/wiki/Glyptodon They aren't around because humans hunted them out. Except the albatr…
The examples you listed, the giant Sloth, the Mastodon, and the giant Armadillo are all actually smaller than a modern elephant so you're not really making your point with those links.
The giant sauropods are thought to have been 10 times heavier than an Elephant.
Ten times heavier! That's enormous.
And the wandering albatross you linked to is said to have existed 50 million years ago in the article.
Re: An asteroid killed dinosaurs in spring, which might explain why mammals survived
#56One thing that isn't talked about as much as it should be, there's a possibility that 65 million years ago during the time of the dinosaurs, the earth's atmosphere was very thick. All these Dinosaurs with their extremely long necks and bodies couldn't support their own weight if wandering around the earth today. The mass extinction event may have occurred simply because the atmosphere changed and these giant beasts u…
I've heard that oxygen levels are lower now than they have been in the past (this seems to change a lot on geological timescales), and that high oxygen levels may help allow megafauna's existence. I wouldn't think it's so much the buoyancy as it is about all the other biological machinery that can operate more efficiently at higher oxygen levels. Oxygen levels are largely driven by algae and plant levels, which of co…
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Re: An asteroid killed dinosaurs in spring, which might explain why mammals survived
#57Earlier quoted context omitted.
If we wipe ourselves out within 100,000 years, I'm not sure "intelligence" is a particularly advantageous trait, evolutionarily-speaking.
For long term survival you need to get off your planet, for which you probably need intelligence. Earth has around half a billion years left until it starts feeling serious issues with our sun. If our evolution took something like 10 percent longer things would be tricky
We could easily seed the rest of the solar system and even a few nearby other solar systems with basic archaea and what not capable of surviving on any large object with water, at least guaranteeing some form of life escapes the death of Earth. It takes intelligence to figure out how to do this, but we have enough intelligence and the means to do it right now, but we aren't since we're largely concerned specifically with human survival, and humans are much harder to keep alive and transport through space.
Re: An asteroid killed dinosaurs in spring, which might explain why mammals survived
#58Earlier quoted context omitted.
> Some 66 million years ago, a catastrophic event wiped out three-quarters of all plant and animal species on Earth, most notably taking down the dinosaurs. The puzzle of why so many species perished while others survived has long intrigued scientists. More importantly, it means that even if we annihilate our specie because of our stupidity, life has great chances going on and in millions of years perhaps, the earth…
If we wipe ourselves out within 100,000 years, I'm not sure "intelligence" is a particularly advantageous trait, evolutionarily-speaking.
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Re: An asteroid killed dinosaurs in spring, which might explain why mammals survived
#59Seems to me that impact spherules are a bit small. Could it be that animal consumed them like today's plastic microbeads?
Re: An asteroid killed dinosaurs in spring, which might explain why mammals survived
#60Earlier quoted context omitted.
Hah, while that could help a bird (if ACTUALLY 10 bar, which is insanely high - 145 psi, compared to 14ish now), it wouldn’t help as much as you would think. At STP, air is 1.3kg per cubic meter, and at 10 bar, it’s still only 11kg per cubic meter. Water is 1000kg/cubic meter. So yeah you could get some bigger birds, but t-Rex or brontosaurus weren’t meaningfully supported by the atmosphere in such a scenario even if…
>> The amount of additional mass required to have a 100 bar atmosphere instead of 1 bar is rather incredible, and there is so far no plausible method known for such mass to disappear. Earth's atmosphere is constantly being blown away by solar wind[1]. I guess after 65 millions years this would add up. But I'm still not convinced if it's possible to loose enough air this way to lower pressure 100 times. [1] https://ww…
If 'several hundred' is, say 500 tons (not sure which definition of ton exactly there, but we'll go with the biggest one of 2240 (or a metric long ton - 1016kg).
That would put it at 508,000kg/day (or 5.08 x 10^5 kg)
If there are 365 days in a year, and 65 million years, we're talking 23.7 billion days (give or take).
So roughly, if the 'high end' estimate was always the case (who knows), and has been happening every day since 65 million years ago, we'll have lost 1.2 x 10^16 kg of atmosphere. Which is a lot of gas.
But how much gas mass is in the atmosphere?
I ran across this interesting article/paper [https://journals.ametsoc.org/view/journals/clim/18/6/jcli-32...], which tries to quantify the dry mass and variations caused by water vapor.
They estimate the total current mass at approximately 5.1352 ± 0.0003 × 10^18 kg
With yearly shifts in mass due to water vapor on the order of 1.2 to 1.5 × 10^15 kg.
As large as the amount of gas that has boiled off (making those assumptions), and if my math is correct, the total amount of gas is 2 orders of magnitude larger. Doing some random scribbling, I THINK it would add up to .2% of the total CURRENT amount of dry air in the atmosphere.
So not enough to make any noticeable difference.