Oh, but they did drive cars! Of course, the fuel they used in those cars contributed to "global cooling", and they could not adapt to the resulting climate change. /s
also, they started playing "chicken", and many died in car accidents.
the high rate of drug and alcohol use also led to many accidents and needless deaths.
also, the claws on their front legs were not good for holding onto the steering wheel, and many lost control of their cars and ran off steep mountain passes.
finally, the foolish t-rex's bought poorly made foreign cars, which folded up like accordions when they crashed into apatosauruses.
the meteor got all the rest, except for a few that mutated into birds.