Scientists believe that this may be the first two-headed reptile fossil ever discovered. The fossil, found in northeastern China, is a choristoderan, an aquatic reptile common 144 to 65 million years ago. The fossil is presented in the current issue of the UK Royal Society's scientific journal Biology Letters. From the BBC News:
"To my knowledge, it is the only record of a vertebrate fossil showing that kind of malformation," Dr Buffetaut, director of research at the Centre National de la Recherche Scientifique (CNRS) in Paris, France told BBCLink
"Living animals like this are known. But if you compare the number of reptiles born with two heads with the total number of reptiles born, it is very small.
"So the chances of finding a fossil like this are extremely low."