Why did the dinosaurs get so big?

Question

Does anyone know why it is that some dinosaurs grew to 50 feet and more, whereas almost all animals today are much smaller? Are we still "recovering" from the dinosaur extinction, and slowly progressing towards larger sizes?

Answer 1

Really interesting questions.
My guess as to why any species grows to a larger size is through predation pressure, for example, elephants don't have a problem with predation from lions compared to the smaller herbivores.
The second part of your question, why are species today not as large as some in the past? may have something to do with the atmosphere then which had a much greater oxygen content. This in turn provided greater plant biomass for the herbivorous dinosaurs to grow large and large predatory dinosaurs to prey on them in turn!?
Larger species though have a legacy, they are generally the first to die out through changing climatic/anthropomorphic conditions, for example, the mega-faunal extinctions about 40 000 years ago. I think it's because these species have a greater generation time (parent-offspring) and are generally in lower numbers (food web theory: trophic levels/biomass). This could explain the diminished number of larger species today
There are probably many other factors though!?

Answer 2

reptiles never stop growing. the early earth had a much better environment for them to exist in ie. they lived a long time. dinosaurs are really only huge lizards. they still do exist today. they don't live as long so they are much smaller than examples of skeletons we see today.also much of the skeletons we see today are put together by men who believe that dinosaurs were very large. they only find part of the skeleton and make the rest from plastic, and assumption.

Answer 3

Good question.
I believe it is known that at that time, there was more
oxygen in the atmosphere. That may have helped.