Most of the more famous dinosaurs were actually from the cretaceous period. T. rex, stegosaurus, velociraptor (and the deinonychus and utahraptor that the movie Jurassic Park’s depiction of “velociraptor” was based on), triceratops, ankylosaurus. Pretty much all the non-avian dinosaurs the average person could name, other than sauropods like brachiosaurus, lived in the cretaceous. Some of those I named did admittedly first evolve in the jurassic, but most are most well-known in the cretaceous.

Though fwiw, birds did first evolve in the jurassic.