French and Chinese paleontologists have identified the fossil of a two-headed reptile, seen here in a sketch, from a species that lived in what is now China nearly 150 million years ago. [AFP]

Paris - French and Chinese paleontologists have identified the fossil of a two-headed reptile from a species that lived in what is now China nearly 150 million years ago.

The specimen was recovered from the Yixian Formation, a treasure trove of fossils in northeastern China that has previously yielded the remains of early birds and feathered dinosaurs.

Only seven centimetres (3.5 inches) long, the tiny skeleton from the Early Cretaceous shows an embryonic or newborn reptile with two heads and two necks.

It was a species of long-necked aquatic lizard that was more than a metre (3.25 feet) when fully grown.

Axial bifurcation -- two-headedness -- is a well-known developmental flaw among reptile species today such as turtles and snakes.

The paper appears on Wednesday in Biology Letters, published by the Royal Society, which is Britain's de-facto academy of sciences.