Dinosaurs invade the Big Apple. Befriending a young diplodocus the Turtles trace the invading dinosaurs to their source finding a lost world.

In an attempt to hijack two separate trains carrying the ingredients needed to make mutagen, Rocksteady and Bebop cause their head-on collision, resulting in the spillage of both chemicals in the city's train yard.

Shredder tricks Usagi Yojimbo into battling the Turtles.

While the Turtles are suffering from turtle pox, a disease that affects only mutant Turtles, Krang has developed a robotic turtle that he calls Metalhead.