Originally posted on sciy.org by Ron Anastasia on Thu 14 Dec 2006 06:39 AM PST
NEW YORK - During the age of dinosaurs, tiny squirrel-like creatures climbed
trees and jumped into the darkness. Then they spread their limbs and glided
away - the first known mammals to take to the air, a new report says.
The species is revealed by a fossil find in northeastern China, which pushes
the known history of mammalian gliding or flying back by more than 75 million
years.
The creature may have even beaten birds into the air.
Like today's flying squirrels, it stretched a furry membrane between its
limbs to provide an airfoil for gliding after it jumped from a tree. But it's
not related to anything living today.
Scientists don't know exactly when the animal lived. Its remains could be
anywhere from 130 million to 164 million years old, said Jin Meng of the
American Museum of Natural History. He and colleagues from Beijing report the
Inner Mongolia fossil discovery in Thursday's issue of the journal Nature.
So it's clearly older than the 51 million-year-old bat that used to be the
oldest evidence of flying or gliding in a mammal. And it has a chance of
preceding the earliest known bird, Archaeopteryx, which flew about 150 million
years ago.
It is much younger than flying reptiles called pterosaurs, which are dated
from 230 million years ago.
Still, added to a recent find in the same locale that revealed a semi-aquatic
creature, the discovery shows that early mammals were a lot more varied than the
land-loving creatures scientists have traditionally envisioned, Meng said.
He and colleagues dubbed the animal Volaticotherium antiquus, which is Latin
and Greek for "ancient flying (or winged) beast."
They believe it was nocturnal, like other mammals of the time were thought to
be, and like gliding mammals are today. It was the size of a flying squirrel or
a bat - less than three ounces. Its stiff tail might have been longer than
the trunk of its body.
The find includes not only bones, but also impressions left in rock that
reveal the furry membrane the creature used for gliding. Its teeth show it ate
mostly insects, researchers said. But it probably couldn't hunt insects while
gliding because it was too clumsy a flier and couldn't stay airborne long
enough, researchers said.
So why glide? It's hard to draw conclusions for this creature specifically,
Meng said, but in general, scientists think that gliding is an energy-saving way
to get from tree to tree, compared to repeatedly climbing up and down trunks.
Gliding probably increased the foraging range of the creature and maybe helped
it escape predators in the trees, he said.
Larry Heaney, curator of mammals at the Field Museum in Chicago who has long
studied gliding mammals, said the new creature "has taken the first step" toward
powered flight like a bat exhibits.
But from its anatomy, "I would say this animal probably was not very far
along the path to true flight," Heaney said. "It was not on the road to the
kinds of modifications we see in bats that allow them to actually fly."
Meng said it's not clear whether descendants of the creature gained the
ability to fly. - end -
Mammals may have flown before birds
(AP)
Updated: 2006-12-14 10:34
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