Who found out about Dinosaurs?

First off, plesiOSaurs and pterodactyl were not dinosaurs. PlesiOSaurs were their own group of reptiles more closely related to lizards than to dinosaurs. Pterodactyl was a pterosaur, which were a group separate from, but related to dinosaurs.

PlesiOSaurs are generally considered to have been discovered by Mary Anning.

Pterosaurs are said to have been discovered by Cosmio Collini.