Witness one scientist's efforts to understand the DNA of extinct creatures so as to better understand the diversity of life today, in this video from KQED's QUEST. 

Professor David Haussler works in the field of computational genomics, which relies on computers to reconstruct the genome of ancient creatures for which DNA is not preserved in fossils. 

By essentially running evolution in reverse, he scans the genomes of organisms that haven't changed over very long periods of time but then suddenly change, resulting in new species that evolve differently from one another.