Why were dinosaurs generally such large animals???

Question

Why were dinosaurs generally such large animals???

Answer 1

it's in their genes and because of the environment.they have a large vegetation of big trres and ferns and so being small is a disadvantage for them as they won't be able to reach for food.i'm talking about vegetable eating dinosuars.

for the meat eating one,they are large because their prey are large.

it's just a balance made by nature.wonderful,isn't it?

Answer 2

Because the planet was mostly a tropical jungle back then, there was a whole lot more oxygen around, which supported bigger beasties.

They got so big as part of the 'arms race' of evolution - outdoing the competition for food and mating.

Ha ha - just mentioning evolution should net me some thumbs down.... Let's watch!

Answer 3

Perhaps plant life was less digestible back in those days.  Is this before or after the appearance of grass?  Less digestible plants would mean bigger vegetarians with bigger stomachs, hence bigger predators.

A plentiful supply of food generally leads to bigger creatures.  The insects were bigger too.  You're less likely to be killed if you are bigger.  Animals that become isolated on small islands generally become smaller.

I think there was more atmospheric oxygen too.

If dinosaurs were cold blooded, then large dinosaurs would have the advantage of being able to retain a warm body temperature for more hours of the day (they have a smaller surface area to volume RATIO).

Answer 4

For every huge one you heard of, Im sure there were hundreds or thousands of small ones that were uncharted

Answer 5

Compared to what? There are still lots of large animals around today, like the Giraffe and Whales.

Dinosaurs, by definition, are large creatures. Trilobites do not qualify.

Answer 6

The largest ones were herbivores. They probably didn't have any natural enemies, so there was no reason for them to be agile. There was plenty of plant food in jurassic period, so all they had to do it eat and migrate to new places if their food ran out. Their huge size helped them to maintain regular body temperature, and their food digestion system was more efficient.

An awful lot of dinosaurs were much smaller though, from elephant-sized to chicken-sized.

Answer 7

climate at the time allowed them to evolve bigger. that's why modern relatives of them are small (they had to survive a couple of ice ages)

the chicken is the modern relative of the T-Rex

Answer 8

its basically reunificaion of simpler molecular tissue organs into a a macroscopic sized entity for which they didnot had a definate size bar

thus to extend upto enormity

Answer 9

It's partly a misleading artifact caused by how humans collected fossils, although some dinos were unusually large for land critters.  People preferred to collect the more spectactular fossils that were easier to see, and tended to ignore the many more small ones that need to be found by sifting through vast amounts of sediments.  There's been a much greater interest in collecting from so called microvertebrate sites over the last few decades, and that's led to an increase in the appreciation and importance of smaller dinos and other critters.

Searching for microvertebrates typically involves shovelling tons of sand, processing it through various sieves, and then processing the residue via various chemical techniques.  That gets rid of most the material.  What's left are things of the right sort of size and density, and these can be fossils of a millimetre or less.  (Dino teeth are larger than that; a few millimetres and upwards.)  Anyway, using a suitable microscope, you now get to spend years looking individually at every speck of material in your residue, and keep the relatively few that are actually fossils.

For some reason, earlier researchers weren't keen on that sort of approach.  They concentrated on biglings.  So do television programme and film makers.

Answer 10

Tis how they evolved harhar!