Beast Wars is the third Transformers metamorphosis.

It was based further into the future after the great war. The Maximals and Predicons lived peacefully. Untill Megatron the predicon commander stole a ship and went back in time to prehistoric earth. The Maximals lead by Optimus Primal flew off after them. both ships crashed on the planet and because of the strong energy fields both sides needed to take on the beast forms of the local animals.
  
   The show has lasted three seasons and has now ended. But luckily it wasn't because of rateings it was because the Beast Wars ended and the Maximals came home in an Autobot shuttle that was found in The Arc.