Winged Fossils

Fossil of oldest beaked bird discovered in China

AP - June 17, 1999

Paleontologists have found a fossil of the oldest known bird species with a beak - an upturned bill resembling Woody Woodpecker's. The 130 million-year-old, crow-sized Confuciusornis dui was discovered last year in ancient lake sediment in China

The fossil was so exquisitely preserved that impressions of its feathers are clearly visible.

Previously, the earliest known toothless, beaked bird dated from about 70 million years ago.

The skull of the Confuciusornis dui fascinated - and amused - scientists. The beak resembles that of pesky Woody Woodpecker.

The creature's beak was an advanced trait for its time, coming only 10 million to 15 million years after the first known bird - the toothy, reptile-like Archaeopteryx - during the Jurassic Period. The Archaeopteryx had a reptilian snout rather than a beak of horn-like material.

The back end of the Confuciusornis dui's skull is primitive, with two openings behind the eyes that are a throwback to dinosaurs.

This combination of primitive and advanced traits suggests that early bird evolution was more complex than previously thought and included many species that didn't succeed.

"This is showing a diversity we didn't know about before. It's not like you have this sort of straight-line evolution from one to another and each one getting more specialized," said Storrs L. Olson, curator of birds at the National Museum of Natural History at the Smithsonian Institution.

Sankar Chatterjee, a professor of geology at Texas Tech University in Lubbock, agreed: "The story is much more complex. Evolution is not really like a ladder. It's more like a bush."

The bird is described in Thursday's issue of the journal Nature. It was analyzed by American scientists and a team from the Chinese Academy of Sciences.

Scientists believe the bird flew well and took off by scaling trees and jumping.

Confuciusornis (kahn-FYOO-shus-OR-nis) dui is the smallest species found to date of the order named for the Chinese philosopher. The birds became extinct 120 million years ago and probably didn't lead to modern birds.

Hundreds of specimens of a larger species of Confuciusornis have also been found at the site, but all lacked intact skulls. Researchers believe the birds fell victim to volcanic eruptions that preserved their remains.

Wings for speed

Most scientists believe birds evolved from dinosaurs. Wings may have evolved not to help the ancestors of birds fly but to help them run faster.

The claim is a new twist in the old argument over how birds first got airborne. It comes from researchers in California who have studied the aerodynamics of the oldest known, primitive bird called Archeopteryx, which lived about 150 million years ago.

Many scientists believe birds evolved from dinosaurs. This means at some stage in history the ancient ancestors of birds must have evolved wings and feathers that enabled them to take off. But opinion is sharply divided over how they actually first took to the air.

Ground up or tree down

Some claim tree-dwelling dinosaurs developed the capacity for flight by gliding from branch to branch. Others think fast-running, bipedal dinosaurs gradually evolved the wings, feathers, and muscle structure necessary to get off from the ground.

Philip Burgers of the San Diego Natural History Museum, and Luis Chiappe of the Natural History Museum of Los Angeles County, ally themselves to this second hypothesis and have used the fossil records of Archaeopteryx to model how the creature might have got airborne.

The creature had an estimated running speed of two metres per second, but would have needed to achieve a minimum of six metres per second to get fully airborne.

Velocity gap

Writing in the journal Nature, the Californian scientists show how Archaeopteryx could have generated enough energy by flapping its wings during its take-off run to close the "velocity gap". Indeed, they calculate the primitive bird could have managed a runway speed of 7.8 metres per second.

"When you put the aerodynamic data that we have based on extinct birds along with what we know about the origin of birds, and what we know of fossil animals and dinosaurs we have found in recent years, I think that it's quite clear that the origin of flight evolved from animals that were predominantly terrestrial."

Thrust generation

But Burgers and Chiappe say that while most discussion about the origin of flight has focused on lift generation, the importance of thrust should not be ignored.

They argue the numerous examples in the fossil record of non-flying dinosaurs with feathered forelimbs and long, veined plumage suggests many creatures flapped in a similar way to Archaeopteryx purely to gain more speed along the ground.

"We wonder what were they doing with those feathered forelimbs if they were not flying," says Dr Chiappe. "I think the answer that we provided in this paper is that they were flapping their wings - they were not flying, but they were increasing their running speed."

Such creatures would have been able to catch prey more easily or avoid being eaten themselves.

BBC Online - May 6, 1999