Quote from: whiterabbit on Jul 13, 2015, 11:46:24 PM
Still how can a 40 foot long predator chase down prey at current oxygen levels? That's extremely unlikely. There needs to be a fuel source (increased atmospheric oxygen) and genetics engineering alone shouldn't affect that. Also where you are affects the amount of available oxygen which is is why all the largest dinosaurs are found in South America vs else where. Atmospheres thicken up closer to the poles if I recall correctly and SA used to be much more south than it is now where as most other continents were equilateral.
Giant sauropods have been found on every continent, throughout most of the Mesozoic. Multi-tonne dinosaurs - both predators and prey - were found in deserts, tundra, savannah, swamps, forests and jungles alike. Albertosaurus and Edmontosaurus migrated as far north as Alaska and as far south as New Mexico. There is no good evidence that dinosaurs were limited by oxygen content, whether locally or globally (and, as I've said before, it's no longer accepted that Mesozoic oxygen was higher than today's).
Their abilities aren't particularly surprising, either.
Advanced ornithischians had a breathing system similar to mammals', with air forced out by a muscular thoracic diaphragm - most of them were lighter than the largest living elephants, which manage to spend hours foraging, travelling and occasionally trotting or fighting, while wielding complex brains and dealing with extremes of temperature. So why wouldn't a similar-sized ornithopod manage?
Sauropods and theropods had a
much better breathing system than ours, similar to birds'. Air sacs in their skeletons allow them to process far more oxygen per breath, maintaining a one-directional flow of air through the lungs and ensuring that they're absorbing oxygen-rich air even while exhaling. It's this system which allows birds to fly at great heights for hours, in conditions where humans need breathing apparatus.
