Something more or less like this:
Baroque:
http://www.youtube.com/watch?v=WQRB3befRMo
Baroque-> Classical
http://www.youtube.com/watch?v=lQpD-EXtvzg
Classical
http://www.youtube.com/watch?v=Zegl7_zMj_Q
Classical -> Romantic
http://www.youtube.com/watch?v=W9CYLAuKdtU
Romantic
http://www.youtube.com/watch?v=KhoYauWJh54
Neo- Romantic
http://www.youtube.com/watch?v=gcBg-tXn0fs
Neo-Romantic just before everybody started doing his own style :P
http://www.youtube.com/watch?v=URKGIa0b_jI
XX Century
http://www.youtube.com/watch?v=hlR9rDJMEiQ
XX Century
http://www.youtube.com/watch?v=LnuN_TORtC4
XX Century
http://www.youtube.com/watch?v=C68SkzGb6Ww
XX Century
http://www.youtube.com/watch?v=jwA8xKAIfbg
XX Century
http://www.youtube.com/watch?v=EoDhmR5eZr0
XX Century
http://www.youtube.com/watch?v=pF-F6-VFCWM
XX Century
http://www.youtube.com/watch?v=ePBB-NO8vKg
It gets more and more complex in harmony, rhythm, colors, form, development, every single aspect of music.
EDIT:
Oh, "Contemporary" suppose to be what composers are writing right now... but in style, not in dates, I could write a baroque piece in year 2013 and it won't be contemporary, some composers live in a period of time but write in another, older or newer.