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Dinosaur discoveries wow Boston
Dinosaur discoveries wow Boston
By BBC News Online's Jonathan Amos
Sensational fossil discoveries were unveiled on Monday, including the most
primitive wishbone yet found in a dinosaur.
Also presented was an exquisite skull from a tiny crocodile that could help
provide vital new evidence on when the landmasses of Africa and South
America split to take up their current positions on the planet's surface.
The finds were described by Paul Sereno, one of the world's leading dino
hunters, at the annual meeting of the American Association for the
Advancement of Science in Boston.
Dr Sereno, from the University of Chicago, told the meeting that science
was on the cusp of a new era in dinosaur discovery. He said Africa, in
particular, would soon yield extraordinary specimens that would enable
scientists to explain more fully how these great beasts evolved.
The wishbone, or furcula, is significant because it informs the debate on
whether birds evolved from dinosaurs; until recently the V-shaped bone was
thought to be a unique feature in birds.
The fossil furcula shown off by Dr Sereno was part of the skeleton of an
11-metre-long predator known as a spinosaur. Although the
110-million-year-old wishbone is not the oldest known to science, the
creature from which it came had a very deep lineage.
"There is an allosaur furcula that is 150 million years old but this is
from the chest of an animal with a more ancient origin.
"We are trying to nail down when the wishbone as fused clavicles first
appeared in theropod (bipedal meat-eaters) evolution. So, this new furcula
is now the most primitive one ever found.
"That's not to say that spinosaurs are closely related to birds; the
wishbone, like many other adaptations, had nothing to do with flight in its
original role. Only later did it become a flexible spring between the
shoulder blades of flying birds - a totally different role."
The spinosaur was uncovered in Niger, Africa, on what Dr Sereno said was an
amazing expedition which brought away 20 tonnes of fossils and rock.
The spinosaur specimen was found within 80 kilometres of the site of the
dwarf crocodile skull also displayed at the AAAS meeting.
This fossil came from a 60-centimetre-long animal that has yet to receive a
formal classification but which has been dubbed the "duck croc" because of
its unusual jaws.
"It has a muzzle that looks like a duck," Dr Sereno said. "It's very broad
but the upper jaw hangs over the lower jaw, so viewed from the side you
don't even see the lower jaw. There's no interaction between the teeth at all."
Dr Sereno thinks this arrangement may have enabled the animal to catch
specific kinds of prey, "such as a frog or a type of fish". Other features
suggest it spent more time out of the water than it. "I think it was more
land-adapted - living on the bank, catching frogs."
Dr Sereno said the 110-million-old skull and other finds from Africa and
South America could upset current views on how the once giant
supercontinent of Gondwanaland broke apart many millions of years ago.
He said there was a big argument over whether Africa split first, meaning
South American animals and plants were more closely related to fauna in
India, Madagascar and Antarctica.
"I think we're going to overturn that now with some of the evidence we have
dug up," he said. "It's going to show that Africa and South America were
very closely related up to about 90 million years ago."
Dr Sereno said he had many more discoveries in the pipeline that would
eventually be submitted to journals for the science community to review.
These include new predatory dinosaurs from India and Africa that hail from
the Cretaceous Period (146 to 65 million years ago).
Dr Sereno said Africa was the "new frontier" in dino research. Specimens
were required from this under-researched part of the world to fill in
important gaps in our knowledge.
"To understand how plate techtonics (the movement of the continents)
affected the evolution of a major group like dinosaurs, we need Africa."