Dinosaur

Dinosaurs' were vertebrate reptilian organisms that lived on Earth from approximately 230 million years ago to 65 million years ago, when a large body impacted on Earth and caused a mass extinction of nearly all the dinosaurs living on the planet. Dinosaurs came in a wide variety of shapes and sizes, with some being carnivorous and others being herbivores.

One of the most advanced dinosaurs to evolve on Earth was the hadrosaur, which prior to the 24th century had been believed to had died out 65 million years ago. However the hadrosaur had not died out, and continued to evolve - eventually becoming the species known as Voth. The Voth eventually left Earth and traveled across the galaxy to the Delta Quadrant. In the 24th century, the USS Voyager (NCC-74656) encountered the Voth, revealing that there was intelligent life on Earth before the rise of humanity. 

On the USS Enterprise (NCC-1701-D), one of the holodeck programs in the ship's computer was for riding dinosaurs. Riders discovered that while the fatality fail-safe would keep them from serious injury, they would still be injured if they fell off a dinosaur.