As VoM said, I feel like there wouldn't be humans as we know it, if dinosaurs didn't go extinct.
The Disney movie "The Good Dinosaur" soft-explores this, actually. The comet never strikes, so dinosaurs keep living and evolving. They eventually learn the art of farming and language, but they don't really build coherent societies or cities like us social mammals do, nor do they seem to have a written language. Meanwhile, they do portrait humans as basically primitive cave-people even though it is 2015. Mammals (and humans) could never evolve to the levels we see in our world, because the dinosaurs were the dominant kind of lifeforms on the planet.
I honestly imagine it would be something like that, but without even cave-people having evolved.