hi there, good question!
I’m not sure. I thought the huge size of creatures in the past was because there were more predators and the bigger they grew & the stronger they were the more likely they were to survive. I don’t know what the history of oxygen density is like but I didn’t think it changed so much…
Interestingly, have you heard of the Australian Megafauna? They were like giant kangaroos (http://en.wikipedia.org/wiki/Procoptodon) and wombats and things which lived in Aus at the same time as the dinosaurs. I think they are awesome. Sadly all extinct now but at least we have our other crazy animals 🙂
Because it has changed over time? Hmmm, perhaps – I don’t know any specifics. More likely reason we don’t see huge animals wandering around is because a lot of those species are extinct – where as smaller creatures have lots of places to hide from predators and adverse weather, larger creatures don’t. There could be alsorts of other effects how lungs have evolved, blood content – an interesting question!
Good question! I think sort of, maybe there was more oxygen back then so the creatures could breath better/more so grew more? I’m not sure really, but I love dinosaurs 🙂
I’m not sure to be honest. I’ve heard of thing you’re talking about – the idea that big creatures can exists only when there is more oxygen in the atmosphere – but I know little about it.
Comments
Sheila commented on :
WOW! I love those giant kangas Suzie!
Suzie commented on :
I know they are amazing!