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Fw: Oldest Dinosaur Fossil
Palaeontologists have found what is likely to be the oldest known
dinosaur, filling in a yawning evolutionary gap.
A study in Biology Letters describes Nyasasaurus parringtoni, a new
species from 10-15 million years before the previous earliest dinosaur
It walked on two legs, measured 2-3m in length with a large tail and
weighed between 20 and 60kg.
The find suggests that many millions of years passed between dinosaurs'
first members and their dominance on land.
"It fills a gap between what we previously knew to be the oldest dinosaurs
and their other closest relatives," report co-author Paul Barrett, of the
Natural History Museum in London, told BBC News.
"There was this big gap in the fossil record where dinosaurs should've
been present and this fossil neatly fills that gap."
However, the team behind the work has stopped short of definitively
calling N parringtoni the earliest dinosaur, because the fossil skeletons
used to define it were incomplete: one upper arm bone and six vertebrae.
The early evolution of dinosaurs is difficult to unpick, as a rich variety
of reptiles were proliferating at the time - and some may even have
independently evolved characteristics that are associated with dinosaurs.
The researchers, from the University of Washington and University of
California Berkeley in the US and the Natural History Museum, re-examined
a number of bones that were first collected from what is now Lake Malawi
in southern Africa.
They saw a few features that are unambiguously those of dinosaurs -
notably what is called an "elongated deltopectoral crest" that served as
an anchor for strong pectoral muscles.
Lead author of the research Sterling Nesbitt, of the University of
Washington Seattle, led a team that in 2010 reported the finding of
dinosaurs' oldest relative, a member of a group called the silesaurs.
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It now appears that those creatures shared the southern part of the
supercontinent Pangaea - now South America, Africa, Antarctica and
Australia - with N parringtoni.
"Those animals were the earliest of this group that led up toward
dinosaurs," explained Dr Barrett. "Now this takes dinosaurs back to the
right kind of time when those two groups would have split apart from each
As it closes that evolutionary gap, it shows that dinosaurs did not start
out as dominant as they later became.
"We push the origin of dinosaurs further back in time to a time when lots
of reptile groups are evolving," Dr Barrett said.
"Dinosaurs start out as a very insignificant group of reptiles - all
relatively small animals, relatively rare in comparison with other reptile
groups - and it's only a bit later in their history that they suddenly
explode and take over as the dominant forms of life for nearly 100 million
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