this is just my theory . I believe that what causing dino to grow so big in Jurassic period is because earth gravitation change. that why only small animal that able to adapt the current gravitation survive while anime that too big can't .

this is proven by bringing deep sea animal to surface, because of change in pressure they die instantly . and also the different in look and characteristic of deep sea fish.


what do you people think about this theory?

umm... i think dinos get so big coz they eat a lot. look at Gustave the croc, he get so huge coz he eat more than usual

just my opinion im no dino expert

Not all dinos were massive though. They came in all shapes and sizes from little buggers to huge monsters.

As for current animals that are huge, you should look at perhaps the whales that can survive today nicely.

Check out evolution and I suspect you will find your answers better on as why some dinos needed to adapt to their changing enviroments to survive by over time getting larger as a species. Just as some needed spikes and plates on their bodies. The ability to run super fast. Or even the needed herd mentality of the raptors for hunting and protection.

there's also small fish in deep sea .



whales is in the sea . whale body adapt to the sea pressure .




for adapt to their changing environment , I read the theory but environment alone is not enough . do you see any huge different in human in living different environment ? the answer is nope .


the reason why I making this conclusion is because of
1. the size , weight and movement speed of dino that predicted just won't make sense with current gravitation (take elephant as example) . if the gravitation is the same then the dino will be crash by the weight . if not they won't be able to run fast . they will run much much slower than elephant .
and those extrema long neck dino should not be able to exist at all .
2. the current tree size (use the oldest and largest as comparison at any place) as source food for herbivore dino just won't be enough .
3. Dino long and big neck/tail .

it's simple theory . if the that period gravity is lighter than now the the tree will grow very huge so will be the animal then the huge size of dino will make sense . and because gravity is light , some can grow they neck as long as it can without feeling the pressure .

if you take gravitation change as the reason then mass extinction of those large dino will make sense .

The reason dinosaurs were so big was probably due to an increased level of oxygen that existed in the earths atmosphere at the time. The more oxygen that exists in the atmosphere the larger the animals will be, plus a slew of other genetic adaptations, like the amount of food that they ate, and the fact that in the world they lived in being huge had many advantages such as being able to eat leaves from the highest branches of trees, and it provided a good defense against large predators, even though the large predators probably evolved due to the need for them to compete with large herbivores. Animals growing large due to necessity is fairly ubiquitous throughout evolutionary history, such as the Megatheriid Ground Sloths, Giraffes, Elephants, Whales, Whale Sharks etc. It also gives them more insulation, either to prevent them from overheating in the sun, or for them to avoid heat loss when it gets cold.

A few articles about the effects of increased levels of oxygen in the atmosphere...

Newscientist.com

BBC News

livescience.com

softpedia

most of this topic is TL;DR

kobolds, your theory is most likely right. As time passes by more and more dust and other particles enter earths gravity causing it to slowly grow, thus increasing gravity. Therefor, it's absolutley plausible that dinosaurs were bigger, since gravity has increased alot since the jurrasic era.

also Like a daydream, this is the first time I've heard about that, thank you, sir!

and because at the time there were high CO2 levels, the plants had very little nutrition so animals had to eat more to get enough nutrition. therefore they needed bigger stomaches

eat alone is not enough . there's a limit a body can grow no matter how many you eat under current gravitation . you can't grow as big as dino, no matter how much you eat . this is because the more you grow fat , under current gravitation , it will give burden to your bones . you will end up crushing your own bones .

gravitation change is the most logical explanation for why dino can grow so huge .

How exactly would gravity change? Gravity is generally correlated with the amount of mass an object has...The earth would have to have lost mass, and then gained some back within the past 65 million years. Which kind of makes no sense, since if the earth lost as much gravity as you are theorizing there would be extreme consequences for all life on earth, since there would be even less of a gravitational pull on the moon, that it might slip out of the grip of the earths gravitational pull causing it to fly off into space, and or causing it to get much further away. Life on earth is very dependent on the moon, it's gravity causes the oceans tides, weather systems, and many more things, along with the spinning of the molten core. The moon is situated at such a point that it is nearly perfect, if it were disrupted to the degree that such a fluctuation of gravity as you have theorized would cause, life on this earth would not exist here today.

what cause dino to grow so huge ?

Wilma flintstone kept feeding him extra kitchen scraps when Fred wasn't looking!

Sorry couldn't resist!

I'm not sure that gravity is the reason dinosaurs were so big, it may be a part of it, but probably only a small part. I have heard a theory that states that a possible reason for dinosaurs size is to outgrow predators. A large dinosaur has little to fear from the smaller predators of the area. Predator dinosaurs grew large so they could prey on these larger dinosaurs. I also think that the oxygen rich atmosphere also lent to their ability to grow so large. Another thing is that possibly the largest animal to ever live is the blue whale that exists today, and a lot of the larger dinosaurs were believed to be at least partially aquatic, to help support their bulk. This is all just my opinion, and I'm only stating what I have heard, but it makes sense to me.

I don't see where you got the idea it had to lose mass, for me it seems it just needs to have gained mass within the past 65 million years, which happens when meteors hit and, as previously said, when dust enters earths gravity. After 65 million years, that's probably alot of wieght gain.

maybe the moon gradually adapts if the change in gravity is very slow, but what do I know, except that the moon is a mean SOB and he ain't going nowhere

I'm saying that it would've had to loose mass because, there were animals before the dinosaurs that weren't giant, therefore it doesn't make much sense to believe that all other land animals before the dinosaurs had 200 million years to evolve to be huge due to the decreased gravity, but only the dinosaurs actually did. The moon is actually escaping from the earths gravitational pull, at a rate of one inch every year.

Dinosaurs, like the mammalian/marsupial megafauna that followed millions of years later, were able to grow very large because of the abundant energy/resources available to them in the ecosystem and the evolutionary pressure to increase in size once the cycle of gigantism began (i.e. prey animals get larger, so only the larger predators are successful in preying on them, but prey mainly on the smaller - relatively - prey animals which increases the occurrence of alleles for gigantism in the population etc and so on). It had nothing to do with changing gravity.

Cause they ate all their spinach......


*Bats her eyelashes*

Hi Leo.......

Hi MUM!!!

Just popped in for a few minutes after getting home from work. Had to leave a message for V, but it's nice to see you here as well.

And they certainly did eat all their spinach , and the broccoli too!!!

Ah! Finnaly an educated woman with appearant knowledge in the field of biology brings us irrefutable proof as to why dinosaurs reached such humongous size. Thank you for solving this riddle, and enlightening us with the thruth! I shall now go and eat my spinach, and I advice everyone to do the same!

thumbs up for you, MUM24/7!

if you asking how or why gravitation change ? my answer will be I don't know how and why the gravitation keep changing over period of time . human understanding on gravitation is very limited .



genetic is also one of the reason whether or not animal / plant can grow big but that alone is not enough . you can see the tree as the example . no matter how old or how tall they can grow , they are limit by gravitation .

if you still not agree then take animal on land and on sea as comparison . you will sea why gravitation is important factor .

Maybe because it was colder aka Bergmann's Rule?

this rule is about the same as environment adapt . no matter in what place/latitude on earth , the different in gravitation is consider very small to make any different unless under water .