The dinosaurs had about 200 million years to evolve and invent technology and they failed. There may be something very special about the human brain.
Of course, the dinosaurs' progress was abruptly halted 65 million years ago. Yet their surviving lineage (class Aves) today has demonstrated tool-using behavior, and certain species demonstrate a remarkable language ability, learning hundreds of words and even showing evidence of understanding the meaning of some words.
How can we prove this? They could have had high technology and there would be no sign of it after all this time.