The Robo-pterodactyl is one of Romeo's many inventions. However, this invention wasn't entirely created by him. He stole a pterodactyl statue from the Museum and added robotic parts to it so it could fly. The robot is large enough to where Romeo can easily ride on its back. The robot itself is operated and directed by a remote.
In "Wolf-O-Saurus", the Wolfys took control of it as if it was their pet.