Mesozoic World

A new theory to explain how dinosaurs learned to fly emerged in 2002. According to a US scientist, flight may have evolved in two-legged dinosaurs which flapped their feathered forelimbs in order to climb slopes.

They eventually developed true wings and became flying birds, according to Kenneth Dial of the University of Montana. The idea was based on a study of the habits of modern flightless birds, which beat their wings to scurry up hills and get away from predators. It turns out that the physics behind this sort of flapping motion are different from those of aerial flight.

Foot traction

Professor Dial stated that this method helps to push the birds' feet against the slope, thereby improving traction - in the same way that spoilers work on a racing car. He came to this conclusion by studying partridges running up hills and measuring their speed.

Even chicks with downy fluff were better at getting up steep slopes than those whose flight feathers had been trimmed or removed. By modifying these wing movements, birds or their ancestors - the dinosaurs - may have been able to launch themselves into the air.

Fossils show that some dinosaurs had feathered forelimbs but were unable to fly - something which long puzzled palaeontologists. The big dilemma had involved the need to explain the partial wing, pointed out Professor Dial.

It turned out that the proto-wings - precursors to the wings which modern birds have - actually acted more like a spoiler on the back of a racing car in order to keep the animal sure-footed even while climbing up nearly vertical surfaces.

Rival theories

Professor Dial believed that what he called wing-assisted incline running was first seen in prehistoric times. But the idea was likely to ruffle a few feathers. There was already a good deal of heated debate amongst academics when it came to resolving the issue of how dinosaurs had learned to fly.

One camp believed that ground-dwellers grew feathers which helped them to run faster and eventually become airborne. A more recent school of thought favoured the idea that flight arose from tree habitation - as small meat-eating dinosaurs leapt from branch to branch in the canopies.

Dr Angela Milner, a dinosaur expert at London's Natural History Museum, pointed to the latest theory as a kind of 'third way'. According to her, this new work served to add a new dimension to the whole debate about how flight had evolved.

She was of the opinion that a predator escape mechanism using wing-assisted incline running fitted in with what could be seen in the fossils.

The research was published in the journal Science. Professor Dial's theory was featured in an exhibition called 'Dino Birds, the feathered dinosaurs of China', at London's Natural History Museum in 2003.

Some images and original text copyright © BBC or affiliates. Reproduction is made on a 'fair dealing' basis for the purpose of disseminating relevant information to a specific audience. No breach of copyright is intended or inferred.