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Days getting longer, scientists say
LONDON, Dec 17 (Reuter) - Days have been getting longer since the time of
the dinosaur when days ran for just 23 hours, scientists say.
With the earth now rotating more slowly, the world's time lords will add an
extra "leap second" to the end of 1995.
Geologists at Australia's Adelaide University, quoted by the Sunday Times
newspaper, believe that more than 600 million years ago, days were just 21 hours
long. When dinosaurs first appeared 250 million years ago, days were up to 23
hours, they said.
Dr Leslie Morrison of Britain's Royal Greenwich Observatory also analysed
records of lunar and solar eclipses to calculate that the world span faster
So the Central Bureau of the International Earth Rotation Service in Paris
is to balance time at the end of this month by adding on an extra second, the
Dinosaur found crouching over eggs like bird
LONDON, Dec 20 (Reuter) - A fossilised dinosaur found incubating its eggs
has offered the most graphic evidence yet of how they may have been the
precursor of the modern bird.
The spectacular specimen, found buried under sand in Mongolia, is crouched
on a nest of at least 15 eggs.
Its hindlimbs are folded on each side of the nest like the brooding posture
of the modern bird, Mark Morell of the American Museum of Natural History
reported in Nature Magazine on Wednesday.
"This finding provides the strongest evidence yet that modern avian brooding
behaviour evolved long before the origin of modern birds," Morell and his
colleagues concluded after studying the superbly preserved Oviraptor.
The fossil, found at Ukhaa Tolgod in Mongolia, contains the dinosaur's ribs
and most of the limbs.
Scientists seek clues to fate of dinosaurs
By Jim Loney
MIAMI, Dec 20 (Reuter) - Ancient glass beads and millenia-old sediment under
the tropical waters of the Caribbean basin may unlock one of Earth's great
mysteries -- what killed the dinosaurs -- scientists said on Wednesday.
One of the world's most sophisticated research ships is set to sail from
Miami this week seeking proof for a theory that the dinosaurs were killed off by
a cataclysmic explosion when an asteroid or comet smashed into Earth and changed
the environment radically 65 million years ago.
The scientists hope to find the answer in the fallout from the big bang --
glass beads, rocks and sediment buried 1,000 yards (metres) under the sea bed
off the coast of Mexico, where according to prevailing theory an
extra-terrestrial body left a giant crater.
They will spend nearly two months near the site of a buried impact crater
called Chixculub, where they will drill into the earth's crust, searching for
answers to the riddle of what killed the great beasts of the Cretaceous era.
"I think I've got the answer. I'm looking for the proof," said Haraldur
Sigurdsson, the mission's chief scientist and a professor of oceanography at the
University of Rhode Island.
Current scientific theory says environmental changes from a comet or
asteroid probably caused the mass extinction of the dinosaurs. But scientists
are not sure exactly how.
They believe the object, probably five to 10 miles (8 to 16 km) in diameter,
plunged to Earth near what is now the city of Merida on the Yucatan peninsula,
creating a crater 100 miles (160 km) in diameter. The impact alone, while
triggering a giant tidal wave, likely did not cause the extinction.
But because it hit an area of shallow water containing a huge deposit of
gypsum, or calcium sulphate, it was "like hitting a powderkeg," Sigurdsson said.
The impact, believed to have been the equivalent of one billion megatons of
energy, probably sulphur-laden gas into the atmosphere.
"That forms a veil over the earth and blocks out sunlight, leads to total
darkness and obviously immediate cooling," Sigurdsson said.
The darkness may have lasted for months or years, killing off plant life and
Scientists aboard the research vessel JOIDES Resolution, the world's largest
scientific drilling ship, will bore holes to a depth of 800-1,000 yards (metres)
near the crater site. The drilling is expected to yield samples of the fallout
from the "big bang" including droplets of molten rock that have turned into
glass beads, Sigurdsson said.
"These droplets of molten rock probably preserved the chemistry of the
terrain," possibly revealing to scientists how much sulphur was present when the
meteoroid hit, he said.