They did! Dinosaurs evolved into modern birds and some of them are extremely intelligent. ... The enormous sauropod dinosaurs lasted on the planet for 100 million years, despite their tiny brains. We've had 'intelligence' for just a few million years, so it's too early to say whether it is a better strategy.

Why didn't the dinosaurs become intelligent?

Ward says that when dinosaurs first evolved during the Mesozoic --- the era spanning some 250 to 65 million years ago --- Earth's atmospheric oxygen levels were much too low for large brains to have developed. “To have enough energy for intelligence is going to require oxygen,” said Ward.

Would humans have evolved if dinosaurs?

“If we speculate that humans had evolved alongside dinosaurs, then they probably would have been able to co-exist,” says Farke. “Humans already evolved in ecosystems that had large land animals and predators. We probably would have done okay.”