Why did dinosaurs grow so big?

Answer 1

Ignore the Lamarckian nonsense that people seem to be spouting here. Dinosaurs didn't grow big to fit their environment anymore than giraffes grew big because they needed to reach tall trees.

Evolution doesn't work that way. The answer is simple, really. At some point in the evolution of dinosaurs, big ones evolved, and they happened to fit a niche, and do well, having enough food to sustain them and oucompete enough other species to stick around for a while. That's all. Until the extinction. For whatever reasons, crocodiles (well, their ancestors) were well adapted to survive the sudden lack of food that came with a prolonged winter. After that the environment just was not suitable again to support giant life, or maybe it just never got a chance to arise again. But certainly, animals do not grow to fit their environment, it's the environment that determines which random mutations are well fitted to survive. If you have a lot of diversity, there's a better c hance of a species surviving when there is a sudden change in the environment.

Answer 2

Because they could. In the Mesozoic there was enough food and space for roaming dinosaurs to attain great size without starving, especially since there were less different habitats and the continents were not as far apart. In these ideal conditions, the dinosaurs were able to grow to a much larger size before their environment would not support creatures of their size. Then there is the fact that the dinosaur ancestor was bigger than the mammal ancestor. (Thecodonts were about 3 feet tall while mammals at the end of the Cretacous were rat sized) so dinosaurs didn't have as far to go to reach incredible size.

Answer 3

Before the earth was flooded about 4400 years ago, the earth was surrounded by a canopy of water that blocked out the harmful radiation rays of the sun. It also keep the oxygen level in the air at a much greater level. The air density was also greater. Dinosaurs are just overgrown lizards. You give them more food and oxygen and the will grow really big. It still happens today to an extent. Lizards will keep growing until they die. It's just now they have less oxygen and they have to deal with radiation the same as humans do. We used to live for almost 1000 years. The less oxygen then the shorter life span.

Answer 4

Actually, there were very few "big" dinosaurs. Most of them that have been found actually average out to be slightly larger than an adult goat.

But, to answer your question, there has been evidence to suggest that the largest ones lived for centuries, and it is quite possible that they grew throughout their lifespans, just like alligators and crocodiles (which some have suggested are the closest things to dinosaurs we have today).

Answer 5

It was better to ask "why did dinosaurs grew so big, compared to human!" and the answer is "why human grows so small, compared to dinosaurs!"

Answer 6

Well the answer to the question is not a simple one. Nor can it be written down in one line.
Well dinasoures grew so big because the ENVIRONMENT they lived then asked them to. I dunno much about o2 conc. & stuff but usually the size is determined by the kind of feed.
Giraff grow tall so tat they can eat the leaves of big tree & stay alive even in the summer..
I guess the answer would be that firstly the herbivorious Dina grew tall & big to feed upon the Flora tat time & in response we had big carnivores tat eat them

Answer 7

by using earth's historic gaseous ecosystem and biochemical surroundings The earth's ecosystem by technique of the time guy appeared in the international had replaced in its gaseous content and ratio and the environmental chemical make up and flora (that are fed on and which promises to the ambience) actually have replaced or advanced otherwise. Such variations restricts the boom of all existence in the international.

Answer 8

Good question. Why are the creatures very long time ago, giant in size? Is it because they have abundant resources not like right now?

Answer 9

Same reason some of them were so small to fit theit habitat and specific needs

Answer 10

Some scientists hypothesize that it's because the concentration of oxygen was greater then.