Cretaceous

In the prehistory of the Earth, the  period was a vast period of time starting approximately 145 million years ago (at the end of the period) and ending approximately 66-65 million years ago. It was the last era of the Age of the Dinosaurs, when an asteroid, the, struck the Earth at what became the in what is now Mexico's , triggering a mass-extinction event that wiped out most of the dinosaurs. The only dinosaurs that survived this cataclysm were the birds. In subsequent time periods, mammals (including humanity) would occupy the dominant niche that dinosaurs once occupied. Mammals had also lived during the Cretaceous, but at the time were smaller, far less dominant lifeforms.

In some Teenage Mutant Ninja Turtles continuities and timelines, the Cretaceous is a time period sometimes visited by Renet using the Time Scepter. In the shared Mirage-IDW prehistory, the Cretaceous is where Time Master was marooned, and from where the IDW continuity's s harvested the dinosaur species  to create the mutant  race to serve the Utrom Empire.