Johnny Galecki is a Belgian-born American actor, best known for his roles as David Healy in Roseanne, Rusty Griswold in National Lampoon's Christmas Vacation, and as Leonard Hofstadter in The Big Bang Theory.
Prehistory is an anthology series of nature documentaries about the history and life of Earth. Each episode follows the stories of various creatures of their time periods, and narrated by celebrity voices. (Very similar to the Walking with Dinosaurs TV shows and Nature) (CREDIT: cover image is "Dinosour Battle Poster" by David Penfound. The creatures' individual images are from various artists and sources.)
