There is more to distinguishing the variation of life on this planet than species. I asked for direct evidence of classes of life being caused by evolution.
Yes there is, and it's called non-scientific distinguishing. By class I am sure you are not referencing this (as my link is the scientific use of "class").
Are you looking for something more like reptiles evolving into birds? Because there is a wealth of evidence on that.
Here's a start:
http://www.msnbc.msn.com/id/18075420/from/RS.5/
http://www.accessexcellence.org/WN/SUA12/dinobird398.html
http://www.sciencedaily.com/releases/2002/02/020214080242.htm
http://en.wikipedia.org/wiki/Feathered_dinosaur