If you were transported 400 years into the past with no clothes or anything else, how would you prove that you were from the future?

If I am transported back in time, 400 years, totally naked, and not able to transport anything along, to prove I am from the future, my options are:

1. Point to my missing gallbladder.
2. Point to my dental work

Both options would required surgery, that 400 years ago, would kill me, so I guess I may be able to prove it, and die in the process.