Why are modern animals so much smaller than dinosaurs?

Question

Everyone knows about all the enormous dinosaurs that once roamed the earth. I've always thought it would be fascinating to see a living creature as large as the dinosaurs, and I've also wondered why modern animals are so small in comparison.

Answer 1

Great question. First, any really large animals that were once wandering around, we drove to extinction. I would also think it has to do with the climate. Dinosaurs were cold blooded so as long as the environment is consistently warm, they can grow large. However, mammals are more limited in having an  self regulating homeostasis.

Answer 2

only some dinosaurs were huge, the blue whale is much bigger than the dinosaurs and its still alive

Answer 3

One of the main concepts of evolution is that things get more simple over time. Hence smaller. It takes too much energy to be big and most likely smaller animals were surviving and pass their genes onto their offspring.

Answer 4

Adaptation. Over time a shortage of food causes smaller animals (who don't require a lot of food) to survive and larger ones (who require a lot of food) to die off. Mammals were enormous before the ice age as well, so it wasn't just dinosaurs. So during the ice age, when food became scarce, large animals began to die off.

Also, what is the point of having a big body if you don't need it to survive? The smallest you can be and still live is the best way to be in natural selection, because it requires less food.

Answer 5

From what I've heard, most dinosaurs were between the size of a large dog and a horse. Only a few were really massive and those are the ones that always get the most attention.

Answer 6

the world is getting crowded and there is practically no place for dinosours to even stand.. how the h**l will they roam.. so modern day animals are getting smaller day by day.... the more the space crunch, the less willl be the size of animals...