There’s another new advertisement mission in Poptropica called Ice Age Dawn of the Dinosaurs. In this mission, you have 90 seconds to help Scrat find twenty acorns. The acorns are scattered around in a small room, but you need to jump around on a lot of very tall cliffs and platforms to get them all. It might take a few tries to get all the acorns in time. You can find the ad entrance in Early Poptropica on Main Street, over to the right hand side where you usually see all of the ad missions. Good luck!
I will post a video walkthrough very shortly on Youtube that helps you find all the acorns in time.