Depending on whom you ask, either Caveman-Jesus rode these all over our flat Earth a couple thousand years ago, or a cataclysmic event ended their reign while the few survivors among them evolved to become, say, birds, Komodo dragons and the creatures brought back to haunt London in one of the greatest Classic Who serials ever.
A dinosaur appears in 1890’s London, and that’s not even the weirdest thing Capaldi must investigate in his debut adventure as the Twelfth Doctor
River marries a robot and pterodactyls prefer sandwiches in this timey-wimey romp!
Dinosaurs in London, another literal sub-plot and the debut of the Whomobile!
Doc and Jo must escape giant graboids inside a jukebox while bureaucrats plot to put a pair of interstellar carnies out of business