1980's dinosaur special with stop-motion animation and Christopher Reeves?

Back in the 1980's my parents taped a dinosaur special off of TV. It was narrated by Christopher Reeves and included stop-motion animation (or possibly claymation) segments depicting dinosaurs. It was my favorite documentary for the longest time growing up, but the VHS has long since deteriorated and I doubt my parents even HAVE the copy anymore. Any idea what the NAME of this documentary was called? I'd like to look it up in case there's a copy floating around somewhere. Thanks!!