Teenage Mutant Ninja Turtles (1987): Season 7, Episode 14

7 - 14: Night of the Dark Turtle

After a fight with Shredder causes Donatello to be struck by a laser beam, his personality changes to become a costumed superhero known as the Dark Turtle. His mission: Seek out & destroy Shredder. Meanwhile, a dinosaur-like alien race called Triceratons, invades Earth.