Dinosaurs could grow larger than the largest terrestrial mammal because they have hollow bones and air sacs just like birds have now. So to build a larger mammal you would have to give it those same hollow bones and air sacs.
Dinosaurs could grow larger than the largest terrestrial mammal because they have hollow bones and air sacs just like birds have now. So to build a larger mammal you would have to give it those same hollow bones and air sacs.