Dust off those thinking caps

Okay, all you word-puzzle-heads: here's a tough one. These twelve entries are given in a particular order. Identify the sequence (please answer via comment), and the first correct will win a mental_floss T-shirt of his or her choice!

1. years
2. uterus
3. enigma
4. accent
5. owl
6. ivory
7. rabbi
8. tropics
9. magistratus
10. scrap iron
11. quasi-art
12. biceps