Were all dinosaurs beasts of a feather?
Feathered dinosaurs may have been the rule, not the exception. A stunning new fossil from China reveals primitive filamentary feathers on a dinosaur only distantly related to birds, indicating that all dinosaurs share a feathery ancestry.
All of the feathered dinosaurs found since Sinosauropteryx startled the world in 1996 come from a group of two-legged predators called theropods, which gave rise to birds. Now Hai-Lu You of the Institute of Geology in Beijing, China, along with three colleagues, has found feather-like filaments on a fossil named Tianyulong confuciusi (Nature, vol 458, p 333).
About 70 centimetres long, the plant-eating Tianyulong lived from about 140 to 100 million years ago. The fossil is a member of the ornithischian group of dinosaurs that diverged about 220 million years ago from the other main branch of the dinosaurs, which contained the theropods. The presence of feathers on both branches of the evolutionary tree suggests they were present in the ancestor of all the dinosaurs.
If the ancestral form had such filaments, then they might be present in many or most dinosaurs - although skin impressions left by large dinosaurs lack feathers, suggesting that the trait died out in larger species.
Feathers might even stretch back to the pterosaurs, which split from the ancestors of dinosaurs shortly before the dinosaur groups emerged. A few pterosaur fossils possess hair-like stubble.
While modern flight feathers are elaborately branched, the new fossil's feathers are hollow single filaments - "the most primitive basic feather structure", says ornithologist Alan Brush at the University of Connecticut at Storrs. Similar feathers still exist on the tail of the 12-wired bird of paradise and in the "beards" of wild turkeys.
credited to newscientist.com
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