Chinese scientists have discovered a missing link in the
evolutionary path between dinosaurs and birds.
Gigantoraptor erlianensis had a small head, a beak, slim hind
legs, a massive body - the size of a Tyrannosaurus - and was
covered with feathers.
It couldn't fly, but it ran like the wind across the plains of
North China 85 million years ago.
It was 8 meters long, 5 meters tall and weighed about 1.4
tons.
Fossil specimens were unearthed in the Inner Mongolia Autonomous
Region about two years ago but the evolutionary link between the
dinosaur and the bird family is being officially released only
today, in Nature magazine.
"It is unique because the dinosaur has a bird's features, but a
much larger body than other known bird-like dinosaur species living
earlier or later," said Xu Xing, a paleontologist from the
Institute of Vertebrate Paleontology and Paleonanthropology
affiliated to the Chinese Academy of Sciences.
Gigantoraptor belonged to the Oviraptorosauria family, dinosaurs
which lived in the Late Cretaceous period (about 65 to 100 million
years ago).
Although paleontologists found no direct evidence of feathers on
the new fossil specimen, they infer that Gigantoraptor probably had
feathers on its body, at least on its arms and tail, because of its
close relationship to other feathered species such as
Caudipteryx.
Gigantoraptor's huge size also challenges old theories.
Paleontologists used to believe that the evolution of the bird's
features was related to the size of dinosaurs.
"But this new dinosaur is an exception. It's features are
different from other smaller dinosaurs of the same family, such as
longer forelimbs," Xu said.
Gigantoraptor lived in the time when Oviraptorosauria emerged
about 130 million years ago and reached its population peak about
70 million years ago.
The earliest birds emerged around 150 million years ago.
The discovery means the evolutionary path leading dinosaurs
toward birds was actually more varied than previously thought.
The research team uncovered almost 80 percent of the dinosaur in
sedimentary rocks of the Late Cretaceous period in Erlian
Basin.
Before the discovery of Gigantoraptor, the largest feathered
animal was Stirton's Thunder Bird (Dromornis stirtoni) that weighed
500 kg and lived in Australia 6 to 8 million years ago.
Inner Mongolia's Erenhot, the city where the dinosaur fossils
were discovered, is planning to build a dinosaur museum to attract
more tourists to the region.
(China Daily June 14, 2007)
