Was earth’s gravity a lot less at one time?

Question

The giant animals that used to live here don’t seem like they could survive or even evolve in our gravity.

Answer 1

Actually, you do need to look at the dinosaurs bone structure, and anatomy.
https://www.theguardian.com/science/2009...
https://www.smithsonianmag.com/science-n...
http://www.sciencemag.org/news/2017/02/z...

Answer 2

African bush elephants were as big as t rex.
It is a fallacy to assume animals in the past were bigger than now, the blue whale is the biggest vertebrate ever

Answer 3

Nope. Dinosaurs were so big because the climate was hot and dinosaurs were ectotherms, meaning they would not bake themselves from the inside out since they do not generate their own body heat. Their large size allows them to keep the heat that their body has, since the larger an object, the less surface area to volume ratio becomes. That means a large object will gain and lose heat more slowly than a small one. In a cold climate, it would mean they would have a hard time warming up, but in a hot climate, they can conserve their body heat better without sunning themselves or sitting on a hard rock to absorb heat. .

Answer 4

No, and the animals survived very well. Remember that the blue (or sulfur-bottomed) whale of today is the largest animal that ever lived. By comparison, the largest dinosaurs were midgets.

Answer 5

Gravity in the Mesozoic was about the same as it is now.

It took millions of years of friendly climate to evolve the giant terrestrial animals. We haven't had that recently -- we're coming off repeated ice ages, which is why we don't have giant terrestrial animals now.

Answer 6

Its something thats always intrigued me

the largest dinosaurs were estimated to have weighted 80 tons

that means each leg had to support 20tons when stood still - or 27 tones when walking (at least 1 leg has to be off the ground when walking)
(thats compares with an elephant at say 4 tons or 1 tons on each leg when stood
I.e the dinosaur leg had to support 20x the weight an elephants leg supports

What intrigues me is- how did the leg bones and joints manage it?

one answer could be- gravity was lower then - so it didnt "weight" 80 tons

But since gravity on earth mostly depends on mass of earth then its mass would have to have been less OR there was some other body that negated some of earths mass (such as moon being closer to earth) OR something has changed in the laws of the universe

(what the f//k has oxygen levels got to do with gravity "robsteriark"?)

Answer 7

Earths mass has not hanged, ergo, neither has gravity.

Answer 8

No, but oxygen levels were higher way back when, and that allowed giant insects and other animals to exist.

Today's oxygen levels simply wouldn't support large, fast-growing dinosaurs, nor do they allow dragonflies with 6' wingspans.

The very largest dinosaurs were also semi-aquatic, such as the brontosaurs, and body sizes can be far larger when animals are supported by water buoyancy. The same is true today with the largest animal being the wholly aquatic Blue Whale.

Answer 9

Well, you are wrong, they did survive, and the gravity did not change.