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发帖数: 14557 | 1 http://www.sciencerecorder.com/news/243-million-year-old-dinosa
243 million-year-old dinosaur discovered in London museum
The world’s oldest dinosaur may have been hiding in plain sight.
Researchers at London’s Natural History Museum say an astounding 243
million-year-old dinosaur fossil has been discovered. The creature, which
has been under study for over two decades, is widely seen as the old
dinosaur ever unearthed by paleontologists.
“If the newly named Nyasasaurus parringtoni is not the earliest dinosaur,
then it is the closest relative found so far,” postdoctoral biology
researcher Sterling Nesbitt said.
Researchers at London’s Natural History Museum last examined the bones in
the 1950s and were unable to identify them, concluding that they came from a
never-before-seen creature.
“We can say, with confidence, the lineage leading to dinosaurs evolved by
the Anisian, the early part of the Middle Triassic epoch, approximately 243
million years ago,” said London’s Natural History Museum in a statement.
The creature, about the size of a Labrador dog, has officially been named
Nyasasaurus parringtoni after southern Africa’s Lake Malawi, where it was
discovered. Speaking Wednesday, researchers say additional research finally
allowed them to accurately pinpoint the age of the fossilized remains.
“It was a case of looking at the material with a fresh pair of eyes,” Paul
Barrett from the Natural History Museum, who worked on the study, said in
an interview with Reuters. “This closes a gap in the fossil record and
pushes back the existence of dinosaurs.”
London researchers say the discovery is especially amazing for the simple
fact that the fossilized bones have been held for so long. First uncovered
in Tanzania in the 1930s, the specimen was the subject of a new study that
allows scientists to date the surrounding rock in an effort to date the
fossilized creature.
“What’s really neat about this specimen is that it has a lot of history,”
Nesbitt said. “Found in the ’30s, first described in the 1950s but never
published, then its name pops up but is never validated.
The discovery, described in the Royal Society journal Biology Letters, means
the dinosaur lineage originated 10 to 15 million years before previous
fossils showed, appearing in the Middle Triassic rather than the Late
Triassic period. Scientists have long posited that dinosaurs (or creatures
similar to them) ruled the Earth at the time, but no definitive has yet been
discovered until now. Using an advanced technique, paleontologists were
able to examine the bone tissue of Nyasasaurus, saying the results are
consistent with what they would expect for an animal at this position on the
dinosaur family tree.
“For 150 years, people have been suggesting there should be Middle Triassic
dinosaurs, but all the evidence is ambiguous,” said Barrett. “The new
findings place the early evolution of dinosaurs and dinosaur like reptiles
firmly in the southern continents.”
While it is hardly uncommon for specimens to be identified long after they
are discovered, researchers say the age of the fossil made accurately
identifying it especially difficult.
“It’s definitely normal for specimens to be described years after their
discovery, but this one was found exceptionally long ago,” says Nesbitt. “
It was probably passed over because it’s not a complete fossil.”
The researchers plan further field work in Tanzania in an attempt to
discover more fossils and build a more accurate picture of the animal’s
anatomy and environment. | a***a
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