Mesozoic World

New findings which were released in 2006 allowed scientists to claim in the journal Nature that mammals took to the skies at least 70 million years earlier than previously thought.

A fossil uncovered in China suggested that mammals were trying out flight at about the same time - or even earlier - than birds. The researchers stated the squirrel-sized animal, which lived at least 125 million years ago, used a fur-covered skin membrane to glide through the air. The creature was so unusual that it belonged to a new order of mammals.

The US-Chinese team said Volaticotherium antiquus, which means 'ancient gliding beast', belonged to a now-extinct ancestral line and was not related to modern day flying mammals such as bats or flying marsupials.

Nocturnal insect eater

The fossil was discovered in the Inner Mongolian region of China. The rock beds in which it was discovered date at least as far back as 125 million years ago, to the Mesozoic era during which time the dinosaurs roamed the planet.

With a length of 12-14cm (5-6in) and a weight of about 70g (3oz), the creature was comparable in size and shape to modern day flying squirrels. It had a fold of fur-covered skin membrane which stretched between its fore and hind limbs. This large membrane, combined with its light weight, suggested that it was an agile glider, although probably not deft enough to capture its prey mid-flight.

V antiquus had elongated limbs, like modern flying mammals, and its skeleton suggested the presence of a stiff tail, which would have acted as a rudder in flight. The researchers believed the creature was tree-dwelling, nocturnal and, because of its sharp teeth, most likely feasted on a diet of insects.

This new find placed V antiquus as the earliest-known flying mammal. Dr Jin Meng, an author on the paper and palaeontologist at the American Museum of Natural History, said he believed the creature lived between 130 and 165 million years ago. With the then-earliest known flying bird, Archaeopteryx, dating to about 150 million years ago, this could have meant that mammals flirted with air travel before birds.

The earliest record of a bat which was capable of controlled flight dates to about 51 million years ago. Before this discovery, the earliest-known gliding mammal was a rodent which lived 30 million years ago in the Late Oligocene period.

The researchers believed the then-gaps in the fossil record for flying mammals were present because the creatures' delicate flying features are difficult to preserve. Dr Meng pointed out the fact that this new evidence of gliding flight in early mammals was providing them with a dramatically new picture of many of the animals which lived in the age of dinosaurs.

Establishing a new order probably only happens once, if that, in the lifetime of a lucky palaeomammalogist.

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