User blog comment:Lord Caesar/Alternate Marvel (my universe)/@comment-4772145-20130122231623/@comment-3291355-20130209012814

The prehistoric creatures idea came from the Savage Land in this universe. Early in its timeline, scientists gained samples of some of the organisms that lived in the Savage Land after it was discovered, most significantly of dinosaurs. This partly leads to the creation of Primitives. The Savage Land in this universe is supposed to have a Jurassic Park feel to it, but I haven't come up with a back story for it yet.