Are you kidding? There were a number of species not too far below the cranial capacity of primates, if not equal to them. If there'd been no asteroid, they could have easily evolved into sentience.
Besides, ever see how intelligent a corvid is, or a parrot? Some of them can even use tools.
They're evolved dinosaurs, remember that ;)
As for this alternate universe ... sometimes you can't explain it except 'the universe where I met the dinosaur me' but there are infinite universes out there, so anything is possible.