Palaeontologists in China said Wednesday they had found the world's oldest flying fish, a strange, snub-nosed creature that glided over water in a bid to evade predators some 240 million years ago.

Fossils in Chinese museum collections have been dusted off, dated and categorised to reveal that the flying fish is a much older creature than thought, the palaeontologists wrote in the journal Proceedings of the Royal Society B.

A specimen named Potanichthys xingyiensis lived in the Middle Triassic period between 235 million and 242 million years ago and is up to 27 million years older than the previous record-holder, a species found in Europe, said the study.

The Triassic geological period predated the Jurassic some 200 million to 150 million years ago, when dinosaurs thrived.

P. xingyiensis presents "the earliest evidence of over-water gliding in vertebrates," co-author Guang-Hui Xu of the Institute of Vertebrate Palaeontology and Palaeoanthropology in China told AFP.

It was already gliding some 80 million years before the emergence of birds, which are thought to be the descendants of small feathery dinosaurs.

Scientists believe that flying fish evolved out of a need to flee attack from predators.

The newly named specimen was only 15 centimetres (six inches) long and had four "wings" -- two big, adapted pectoral fins and a smaller, auxiliary pelvic pair.

The fish had a large, forked tail fin that may have been used to launch it for over-water gliding.

Xu said this was the first flying fish ever to be found in Asia from the prehistoric Triassic period, a time when the super-continent Pangaea was starting to break up into the different landmasses we know today.

The only other Triassic flying fish hitherto known were somewhat younger and came from Austria and Italy.

Potanichthys xingyiensis is a composite term meaning "winged fish of Xingyi", the Chinese city near which the fossil was found.