- Chinese palaeontologists have uncovered the most complete
fossil yet of an ancestral tyrannosaur, and found that filamentary
protofeathers
covered its body. Feathers and protofeathers had been found on related
dinosaurs, but not on an early tyrannosauroid.
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- The new animal, named Dilong - from the Chinese words
for "emperor dragon" - was lightly built and about 1.5 metres
long. It lived between 128 and 139 million years ago, predating
Tyrannosaurus
rex by 60 to 70 million years.
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- Xing Xu and colleagues from the Institute for Vertebrate
Paleontology and Paleoanthropology, Beijing, found a partly articulated
skeleton with a nearly complete skull, plus two other skulls and additional
bones.
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- The skulls show some traits which became magnified in
later and larger tyrannosaurs, but the body is barely more specialised
than the most primitive of the feathered dinosaurs, Sinosauropteryx.
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- Skin imprints
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- The protofeathers appear on the tail and jaw of one of
the Dilong fossils. The filaments on the tail are branched and up to 2
centimetres long, spreading at an angle of 30 to 45 from the tail
vertebrae.
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- Xu and colleagues note that Dilong's feathers are
probably
a series of filaments joined at their bases to a central filament, like
those which covered the body of Sinosauropteryx.
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- The only known skin imprints from Tyrannosaurus rex show
scales, but Xu suggests the giants may have lost their feathers because
they no longer needed them to keep warm - just as modern elephants have
lost their hair.
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- Closely related dinosaurs had already been found with
feathers, so palaeontologists had expected them on early tyrannosauroids,
but the discovery was still gratifying, Tom Holtz of the University of
Maryland told New Scientist, "It's nice to have a fossil that is a
confirmation, rather than a total surprise."
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- Journal reference: Nature (vol 431, p 680)
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- http://www.newscientist.com/news/news.jsp?id=ns99996500
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