While trying to get the dinosaur back, the Smurfs get trapped in time when they lose the key's crystals. This episode was originally featured as a three-part episode and was later broken into two separately titled episodes when it was aired in syndication. Parts 1 and 2 were combined into a single episode, retaining the original title, while Part 3 became "Lost In The Ages".
Elenco: Don Messick , Lucille Bliss , Frank Welker , Michael Bell , June Foray , Paul Winchell , Danny Goldman , Hamilton Camp , William Callaway .