The Cretaceous was a geological period in Earth history that ended 65 million years ago.
The dinosaur genus of hadrosaur lived in the Cretaceous. At the end of this period, a mass extinction brought about by an asteroid impact led to the disappearance of the hadrosaur and other dinosaurs. (ENT: "Azati Prime"; VOY: "Distant Origin")
Appendices[]
While never specifically stated on screen, the Triceratops, Tyrannosaurus rex, and Velociraptor all lived during the Cretaceous and fell victim to the extinction event at its end. Although stated to be a Pterodactyl (Jurassic), one of the flying reptiles seen in TAS: "Once Upon a Planet" appears to be similar to a Cretaceous period Pteranodon.