Terrorsaur was in the Beast Wars from the beginning and survived until the end of season one. He was an original member of Megatron's crew and when he landed on Earth, he took the beast form of a a pterodactyl. His powerful form enabled him to fly and gave him a handsome red robot form. Unfortunately, the screech of the pterodactyl carried through into his voice and he had an annoying scratchy voice.
Unlike Scorponok, Waspinator and Inferno, Terrorsaur was not a blindly loyal follower of Megatron. He had his own idea on how the Predacon base should be run and thought himself best as leader. He tried a few times to overthrow Megatron, but his attempts never lasted very long.
In the episode Power Surge he found a stack of energon as a result he became more powerful and went to attempt to defeat Megatron and take control of the Predacons. Due to his power surge he defeated Megatron and proclaimed himself as their new leader. The energon surge was running low so he had to back to get more. Whilst he was gone Scorponok had Megatron salvaged and rebuilt. Optimus Primal and Rattrap managed to blow up the energon store. To Terrorsaurs dismay and surprise a rebuilt Megatron awaited him.
He wasn't very friendly with anyone in particular and was more focused on his own goals and ambitions. When the quantum surge, caused by an explosion of an alien device in space, hit the Predacon base, Terrorsaur and Scorponok fell into the lava pits beneath the base and melted out of existence.