No that’s absolutely false too. Atmospheric oxygen was lower during the Jurassic and Cretaceous than it is today.
It peaked during the Carboniferous period, and then started declining in the Triassic and bottomed out right around the Triassic-Jurassic extinction event 200MYA, then rapidly increased again. Dinosaurs became the dominant terrestrial species after this, and all of the huge dinosaurs lived during the Jurassic and Cretaceous.
They do need extra oxygen to do anything, though. They might be able to walk around, but they’ll tire quickly if they have to do any exertion.
Whales don’t have to run on land, and the biggest ones have no predators besides humans.
No that’s absolutely false too. Atmospheric oxygen was lower during the Jurassic and Cretaceous than it is today.
It peaked during the Carboniferous period, and then started declining in the Triassic and bottomed out right around the Triassic-Jurassic extinction event 200MYA, then rapidly increased again. Dinosaurs became the dominant terrestrial species after this, and all of the huge dinosaurs lived during the Jurassic and Cretaceous.
https://www.sciencedaily.com/releases/2013/11/131118081043.htm
Studies of air bubbles trapped in amber revealed atmospheric oxygen levels of 10-15% during the time the largest dinosaurs existed. We have 21% today.
Great, so they’d hyperventilate and keep getting dizzy. A bunch of hyper oxygenated, dizzy velociraptors. What could go wrong.