Prehistoric parachuting birds were mere featherweights when it came to flying

 

THE EARLIEST feathered dinosaurs were either “parachuters” or gliders, but they could not fly, according to new research. While their feathers were similar to those of modern birds, they were not near strong enough to keep these ancient “dinobirds” aloft.

The finding potentially brings to an end long-standing arguments about whether fossil birds dating back as far as 145 million years could sustain flight by flapping their wings.

The result comes from a research collaboration involving scientists based in University College Dublin and the University of Manchester. Their findings are published this morning in the journal Science.

“They were either parachuters or gliders,” Dr Gareth Dyke, senior lecturer in UCD’s school of biology and environmental science said yesterday. The animals in question were the earliest known feathered dinosaur archaeopteryx dating back 145 million years and confuciusornis that lived 120 million years ago.

They were definitely not flapping flyers, Dr Dyke said, because their feathers were not strong enough to allow proper flight. They would have bent or broken under the strain.

It was not because the two dinobirds were particularly heavy. Rather, their feathers were simply not up to the rigours of flight. They were too weak, according to Dr Dyke and his research collaborator from Manchester, Dr Robert Nudds.

Fossil examples of the two animals are plentiful and so the researchers were able to analyse wing and body shape and measure the primary feathers essential for flight. They then calculated the forces that would act on the feathers during sustained flight, when gliding, and during a parachute-style leap with curved wings used to slow descent.

Feather strength is linked to the strength of its rachis or quill, Dr Dyke said. The quill supports the feather and prevents bending and breaking. Although the dinobirds have feathers very like those of modern birds, their feather quills are much thinner and weaker, he said.

An archaeopteryx feather is 10 times more likely to break than the feather of a modern bird of similar size, and a confuciusornis feather is 100 times more likely to break than one of a modern matching bird, the researchers found. “If the feather structure of these animals was the same as modern birds . . . these animals could not beat their wings. They would have broken their feathers,” Dr Dyke said.

It is even doubtful that gliding would have been a possibility, although they have the correct muscles and shoulder anatomy to allow this. And parachuting was also a possibility, with curved wings used to slow a leap from tree to tree.

The research project itself had a fortuitous beginning when Dr Nudds was on a visit to Dublin.

“We came up with the idea in a pub while waiting for a Dart train,” Dr Dyke said.