Board Thread:General Discussion/@comment-26237273-20150617140442/@comment-1187034-20150717204145

There is no evidence of Stegosaurus on Isla Nublar, so unless there's evidence that says otherwise there were no populations of Stegosaurs before Jurassic World. I'm pretty sure Troodon went extinct at least during the clean up of Jurassic Park or during the construction of Jurassic World.

I like to think that the Parasaurolophus, Triceratops, and Gallimius that live in Jurassic World are descendants of the populations that survive the 1993 Isla Nublar Incident, somewhat like Rexy.

I think Herrerasaurus went extinct in the wild due to competition from Velociraptor and other advanced carnivores.