the abnormal animal, belonging to a group of aquatic reptiles, was unearthed in northeastern China and dates to the time of the dinosaurs.
The specimen reveals that it must have been very young when it died and became fossilised, says lead researcher Eric Buffetaut.
Details of the fossil appear in the uk royal society journal biology letters
The animal was a choristoderan, an extinct reptile that reached a length of one metre in adulthood and was characterised by a long neck two in the case.
The animal's spinal column divided in to,at the point where the neck emerges from the body. This formed two long necks that ended in the skulls.
Choristoderans seem to have been common aquatic reptiles during the cretaceous period (144-65 millon years ago ) in what is now northeastern China.
The specimen comes from cretaceous rocks in the yixian formation of northeastern china. It is now held at the shenzhen museum in southern china.