Turtles at the Earth's Core is an episode from season 3 of the 1987—1996 animated Teenage Mutant Ninja Turtles series.
A Tyrannosaurs Rex is seen in New York City. The Ninja Turtles follow it from the hole in the ground, through which it came, and find themselves in an underground cave where dinosaurs still exist.
Life in the underground cave relies on a crystal. atop a mountain Krang, Shredder, Bebop and Rocksteady are also there, and they attempti to steal the crystal and repower the Technodrome. By the end, the turtles, accompanied by Dippy the diplodocus, defeat their antagonists and restore the crystal.