>>5059981
I believe that the shitty air quality of the early triassic post-great dying had something to do with it. if animals around that time wanted to live active lifestyles then they would be pressured into developing very efficient body plans, the oxygen levels around that time were critically low at 12% for reference. so bipedalism and an advanced respiratory system were a winning combo that stuck with the theropods all throughout their reign. it's also what allowed them to become gigantic too since they essentially had super charged highly efficient biology when the environmental conditions finally improved, and them becoming big is what allowed the sauropod theropod size arms race to begin. so ironically dinosaurs got big due to low oxygen levels instead of high oxygen levels like those retarded bait theories say.
