Science Books!

When I was a young boy, there was an illustrated book series about the history of life that I loved.  It had wonderful pictures, and went pretty in depth-- identifying reproduction as the main line of whether something lives or not, detailing the problems of animals moving from sea to land, showing the causes of great extinctions. The books probably are not still up to date, but they were fantastic and they really put a sense of wonder about creation in you.  The books were separated out in sections-- I believe they roughly correlated to geologic eras. There must have been about 6 or 7 in the series.  I, however, cannot find these books, even after a ton of internet searching.  It certainly doesn't help that I have no idea what the book series is called.  The last place I remember seeing one of these books is at the Urbandale public library... like in 1998.  I would love to get my hands on them, however. If anyone has any leads...