Also a 70s live-action Saturday morning TV show, featuring a family stranded in a strange world with dinosaurs, cavemen, and some strange creatures like the Sleestaks and strange things like the pylons. The first season was really good, as they explored and developed this fictional world in a well-thought-out, internally consistent manner, as both the characters and the audience gradually learned more about the history, laws of physics, and inhabitants of this world. The second season was a little uneven, as the writers seem to have run out of good ideas that were both original and consistent with what had gone before, and seemed to be thrashing a bit. The third season really sucked, as the writers by then seemed to have lost all interest in making any sort of sense, either in the real world or the fictional one, and just threw in every bizarre plot twist they could come up with. The show went off the air after that, though I think there was some sort of remake in the 90s which I haven't seen.