[PUGACHEV]

I've always wondered why some animals in ancient times were so much larger than today. Was it because their predators or their prey was larger, sort of like an arms race?

[varmintman]

I've always wondered why some animals in ancient times were so much larger than today. Was it because their predators or their prey was larger, sort of like an arms race?

One word: gravity..... It's a fairly easy demonstration that the larger dinosaurs could not function in present gravity. There are different theories as to why gravity might have been different in ancient times.

[C19fan]

At least in terms of this turtle and Titanoboa the rain forest they lived in were much warmer than say the Amazon forest is enabling these cold blooded reptiles to grow much bigger than anything in the Amazon today.

[C19fan]

At least in terms of this turtle and Titanoboa the rain forest they lived in were much warmer than say the Amazon forest is enabling these cold blooded reptiles to grow much bigger than anything in the Amazon today.

[MetaThought]

My personal theory is that it was the higher atmospheric CO2 levels that allows larger animals and the larger vegetation to support the animals.