[Lorento]

What kind of information would we lose, besides information about the extinct species themselves? For example, are there unsolved questions in science that could be solved if we still had a specimen of a missing species? I don't see that it's interesting to study an extinct species for its own sake, since we would be lost in regret at not still having dinosaurs, etc. too.

[rangibaby]

http://en.wikipedia.org/wiki/Star_Trek_IV:_The_Voyage_Home

[gohrt]

Many species have unique biochemical/mechanical features, which are interesting and possibly usable in other technologies.