In which period on the geological time scale were the dinosaurs dominant?

A.

Quaternary

B.

Cambrian

C.

Devonian

D.

Triassic

Quartnerary is our time period or it may have been the period before that. But it's the most recent era. Cambrian was full of early life forms, mostly water based. Devonian is sometimes referred to as the 'Age of the Fish'. Triassic was one of the 3 main dinosaur periods, others being Cretaceous and Jurrasic. So the answer is Triassic