How can you people be so blindingly stupid?
Approximations and such are used in these models, which is why it says 160+/- 20 million years. That's a very large error (12.5%) but it's good nevertheless.
Luke Wells: try studying a bit of classical mechanics. You mgiht be surprised what can be predicted / traced back through planetary motion.
Chris Morrison: Before you disbelieve, try doing it yourself / looking at the paper and also realise that there is a reason for the error stated.
Whether science actually takes anything for fact or whether all we know is a succession of better and better approximations is a bunch of philosophy i'm not going to go into.