Gravity and dinosaurs

Okay, thread kind of deviated off.

I think I can answer the OP, the reason why they area able to pumb thier blood is because it is a pressurized system. A pressurized system makes it alot easier to pump the blood and is affected very little by gravity.

Think of it this way, sea creatures survive under tremendous pressure in the depths of the oceans, but they are still able to pump thier blood.

Hope that helps.

reply to post by battl3star


Well mass isn't the only thing that determines the surface gravity of a planet.....You have the mass which exerts a gravitational force, but you also have to figure in the radius. For instance here's an explanation from Wikipedia

"For example, the recently-discovered planet, Gliese 581 c, has at least 5 times the mass of Earth, but is unlikely to have 5 times its surface gravity. If its mass is no more than 5 times that of the Earth, as is expected,[5] and if it is a rocky planet with a large iron core, it should have a radius approximately 50% larger than that of Earth.[6][7] Gravity on such a planet's surface would be approximately 2.2 times as strong as on Earth. If it is an icy or watery planet, its radius might be as large as twice the Earth's, in which case its surface gravity might be no more than 1.25 times as strong as the Earth's."

The unfortunate thing is that this fact doesn't do much to help the theory...as I understand it a larger planet will have less surface gravity than a smaller one that has the same mass. So we'd still be dealing with an increase of mass, even if a way was found for the Earth to expand without becoming more massive, it wouldn't make the gravity more...if anything it would make it less! I still like the theory as it would explain a lot......there's just a hard time trying to find a logical mechanism that could explain it.

reply to post by KingAtlas


I would think that if the sauropods had a pressurized system they would bleed to death if they were wounded. Is this belief supported for land animals? Any references?
You are right....there are many sea creatures that are able to adjust internal pressures to match ambient sea pressure but it is the vertical distance (i.e., between heart and brain) where the pressure is affected by gravity....not an issue for sea creatures.

Originally posted by bhornbuckle75
reply to post by battl3star

 

Not to mention the fact that so many creatures that we have today were much larger....Heck prehistoric dragonflies had three foot wingspans! Add to that the fact that modern paleontologists still have difficulty explaining how anything as large as some of the pterodactyls ever got airborne. For instance they say the bigger ones could have only gotten airborne by jumping off cliffs like hang-gliders.....which would mean they'd have a horrible time getting back up to the cliff if they accidentally landed on the ground below it! How exactly did they capture food while hang-gliding around? This would seem to me to be an obvious evolutionary disadvantage....yet the evolved that way....

Of course all of this makes sense if the gravity on the planet earth was a tiny bit less. It's a concept I really enjoy thinking about, but it's hard to find a theory that can make it fit. Some versions of the 'expanding earth theory' might work...but I've never heard a really good explanation for how the process might work

edit on 26-10-2011 by bhornbuckle75 because: no reason....I just like to edit.

You are kind of ignoring a possibility. Maybe they didn't "fly" but just glided down. Look at flying squirrels, flying snakes, sugar gliders. Lots of critters still use extra skin to glide to areas they can't jump to.

So they climb a cliff face near the ocean and they look for fishes or something the rightsize, near to the water, under the water, and they jump off, swoop in, grab it in their beak and swoop over to the beach and eat it.
Then they walk similarly to how a Bat walks, back to the cliff, climb like a bat climbs, and wait for something the right size to show up again.

That's not an inefficient way to exist if it gives you an advantage in catching a specific type of food, while avoiding other risk factors. It would mean that if your food supply ever changed radically, you'd probably suffer extinction. Or you'd adapt and evolve into a better version of a bird.

I've always assumed that the moon was closer then, thus lowering the surface gravity of earth through a shared gravitational bond. 75 million years ago there could have still been debris clustering around the moon from it's formation.
I've often wondered if the meteorite that killed off the dinosaurs wasn't a part of the moon that circled back in a system orbit and thus couldn't avoid hitting the earth. For a good billion years that could have been routine and daily for bits of the moon/earth collision to come circling back round and smash into either the moon or the earth.

When was the last time anyone noticed a meteorite hitting the Moon and making a new crater???
I' haven't heard of any new craters in my lifetime.

If I remember correctly the moon is slowly falling out of earth orbit, and has been since it's creation when it failed to become wholly a part of the earth.

Everyone forgets about the moon and the fact that it's E-ffect on the gravity of this planet A-ffects every living thing on it.

Originally posted by Megapixel
The only theory that adequately explains the gigantism of the dinosaurs is the Gravity Theory of Mass Extinction (GTME). Briefly, the theory posits that surface gravity on the Earth (in this case on Pangea) was reduced by the shifting of the core elements (inner/outer cores and lower mantle) in response to the coalescing of the continents forming Pangea. When continents move latitudinally, they would alter the Earth's angular momentum if there were no compensating action. The Law of Conservation of Angular Momentum mandates that this cannot happen to the Earth without some external torque. Therefore, something had to happen to offset the continental movement's change of angular momentum. GTME posits a shift of the core elements away from Pangea as the compensating action.

A movement of the core elements away from Pangea would necessitate a reduction of surface gravity on Pangea. The rapid breakup and dispersal of Pangea 60 to 70 mya would have caused an increase in surface gravity, gradually and eventually causing the extinction of the dinosaurs (except birds, of course).

That sounds interesting...I've never heard of that theory before. I need to check into it in a bit more detail to see if it makes sense, as I couldn't quite follow it from the brief, but intriguing description you gave. Do you know of any links that describe this theory in depth? Otherwise I suppose I'll just Google 'Gravity Theory of Mass Extinction' and see what pops up.

Thanks for introducing me to a new, intriguing angle on this subject!

You are kind of ignoring a possibility. Maybe they didn't "fly" but just glided down. Look at flying squirrels, flying snakes, sugar gliders. Lots of critters still use extra skin to glide to areas they can't jump to.

So they climb a cliff face near the ocean and they look for fishes or something the rightsize, near to the water, under the water, and they jump off, swoop in, grab it in their beak and swoop over to the beach and eat it.
Then they walk similarly to how a Bat walks, back to the cliff, climb like a bat climbs, and wait for something the right size to show up again.

That's not an inefficient way to exist if it gives you an advantage in catching a specific type of food, while avoiding other risk factors. It would mean that if your food supply ever changed radically, you'd probably suffer extinction. Or you'd adapt and evolve into a better version of a bird.

Actually If you read what I wrote, I clearly covered the gliding angle....in fact the main objection I pointed out was how difficult it would be for creatures such as this to climb back up a cliff if they ever landed on the ground below. Small animals like bats can climb just fine...but when's the last time you saw an elephant climb a cliff?....or in this case a creature with a 30 foot wing span (which is a conservative estimate of the size of some of the larger creatures....some have estimated they may have gotten as large as to have 50 foot wing spans)....that's a lot of loose skin folded between your arms to be doing any climbing!

reply to post by bhornbuckle75


There is a website that describes GTME (dinoextinct.com) but the full theory is in a book 'The Gravity Theory of Mass Extinction.'
The theory is based on the premise that the distribution of the continental plates, which can vary widely (see scotese.com), determines the position of the core elements. When the center of gravity of those continental plates moves above or below the equator, the core elements move off-center. My earlier post on Conservation of Angular momentum explains why this happens.

When the core elements move off-center, the distance from the core elements to various points on Earth's surface varies, and therefore, surface gravity varies. In the case of Pangea surface gravity was lowered (lowest near the equator and higher toward the poles). This is why some dinosaurs grew to immense size.

There are many facets to the theory including the affect on magnetic reversals, which would be affected by the core movement. Recently, a research group unknowingly verified this part of the theory---google "continents may reflect conditions in the Earth's core" for this information.

The force of gravity is determined between two objects.(like the dinosaur and the earth) It has nothing to do with other objects for the most part. The moon has nothing to do with the gravitational force between you and the earth.

Now, there is also a gravitational force between the moon and the earth or the moon and the water on the earth but remember that the moon orbits the earth... so even if it were closer... the effect would be cyclical...and the gravity that a dinosaur and the earth has is MUCH greater than the Moon's gravitational force on the dinosaur.

Gravity directly proportional to the product of the masses of the two objects and inversely proportional to the square of the distance between them. In effect this means that because the moon is so far away compared to the distance to the earth that the gravitational pull of the earth is hugely different.

This inverse square rule is seen all over the natural world.... in things like magnetism, light intensity...etc.

We have some animals today that are not too different in height than dinosaurs.....pumping blood is purely a problem of the difference in height.., hence a difference in pressure with greater height.

The giraffe has issues similar to this... but has evolved a circulatory system that allows blood to be pumped to his/her head. It requires enormous blood pressure to do this... and the giraffe has a special blood pressure regulating organ in the head that allows it to move its head from ground level to full height without fainting. (Which would be embarrassing for the giraffe...)

I hope this helps in your discussion.

how big is a dinoheart?