New Cretaceous bird fills fossil gap

[Guy Leahy <xrciseguy@sbcglobal.net>]

Fossils show living birds descended from waterfowl 
By Maggie Fox, Health and Science Correspondent
1 hour, 32 minutes ago
 
A set of 110-million-year-old fossils from China is
the earliest example of a modern-looking bird and
strongly suggests ancestors of all living birds were
waterfowl, researchers said on Thursday.

The pigeon-sized bird probably resembled a tern or a
loon, the researchers said. Called Gansus yumenensis,
it would have been an accomplished flyer and diver and
could well be one of the ancestors of modern birds,
the researchers report in Friday's issue of the
journal Science.

"Every bird living today, from ostriches ... to bald
eagles, probably evolved from a Gansus-like ancestor,"
Matthew Lamanna of Carnegie Natural History Museum in
Pittsburgh told a news conference.

Peter Dodson, professor of anatomy the University of
Pennsylvania, who oversaw the research, said, "Gansus
is very close to a modern bird and helps fill in the
big gap between clearly non-modern birds and the
explosion of early birds that marked the Cretaceous
period, the final era of the Dinosaur Age."

The five skeletons come from an exceptionally rich
fossil bed in China's Gansu Province, in a poor
farming area near Changma, 1,200 miles west of
Beijing.

In the Cretaceous period, 100 million years ago, it
would have been a lake, surrounded by lush plant life,
filled with crocodiles and fish, and with dinosaurs
and early mammals prowling on land.

Now the lake bed survives as layers of rock.

"You can walk up to a rock and peel off sheet after
sheet like paper until you get to a fossil," said
Jerald Harris of Dixie State College of Utah.

Hai-lu You of the Chinese Academy of Geological
Sciences was studying at the University of
Pennsylvania when many earlier fossil birds were
discovered in China's northeastern Liaoning Province.
He remembered that the rock beds in Gansu were similar
and took an expedition there.

They struck paleontological gold and quickly gathered
five nearly complete fossils of the early bird.

A computer program reconstructed the bird evolutionary
tree and suggests the birds that gave rise to modern
birds were waterfowl.

Gansus looks more like a modern bird than some birds
that lived later in the Cretaceous period.

Its wings, legs and webbed feet closely resemble those
of living loons and diving ducks, with a few
exceptions. The birds had not yet evolved the hollow,
air-filled bones that make modern birds to light and
nimble, and it still had tiny claws at the end of its
wings that probably would have made it slightly clumsy
in flight, Harris said.