by TrinidadMMorganti » 24 Jan 2011, 01:58
Well, they couldn't exist, because they require a very different ecosystem to survive and thrive.
However, if they were somehow walking around, they would thrash the global food-web. The dinosaur herbivores would displace today's herbivores, not just by size and competition, but because they just eat so damn much (assuming that they could happily eat modern plants). I suppose that the predator species would similarly wreak havoc on our prey species.
Still - I have to guess that if they did suddenly appear, everything would eventually reach a new equilibrium, with our dominant mammalian species and new dinosaur species falling into line in a manner that everyone could live with. Sure, some species of each would completely die off, because you'll never have 100% adaptation, but we would end up with a modern animal - Cretaceous animal balance.