Zander
Explorer
The only known fossil of a two-headed reptile has been found in China. The species is thought to have normally had one head. This seems to be a mutant that died young, maybe before birth.
Link: http://news.bbc.co.uk/1/hi/sci/tech/6195345.stm
Link: http://news.bbc.co.uk/1/hi/sci/tech/6195345.stm