Did T. Rex Sport a Down Coat?

Earth’s fiercest family of predators -- the toothy tyrannosaurs -- may have been cloaked in downy feathers like a baby bird, a new fossil discovery in China suggests.

Scientists at the American Museum of Natural History in New York and the Chinese Academy of Sciences announced this week they had unearthed unusually well-preserved fossils of the earliest known ancestor of Tyrannosaurus rex in western Liaoning province in China.

The 128-million-year-old fossils preserve clear impressions of lacy feather-like filaments from head to tail, offering the first direct fossil evidence that the skin of these predators was plumed.

Formally named Dilong paradoxus -- the surprising emperor dragon -- the slender, 4-foot-long carnivore had unusually long arms and three-fingered hands. Rows of curving, blade-like teeth lined its jaws. Its primitive feathers may have served to keep it warm, researchers said.

The discovery, detailed in the current issue of Nature, adds to an emerging mosaic of dinosaur characteristics that emphasizes their kinship with modern birds, said American Museum of Natural History paleontologist Mark A. Norell, who was studying the find in his office this week.

So many hundreds of fossils of feathered dinosaurs have come to light in recent years that it was not the existence of feathers that made the discovery so interesting to scientists, but rather its claim to be the earliest known ancestor of all the tyrannosaurs -- the last and most successful of the carnivorous dinosaurs.

“We have a lot of feathered dinosaurs now, so that was not so exciting,” said Xing Xu, a paleontologist at the Institute of Vertebrate Paleontology in Beijing, who was the lead author of the research paper.

“Then we realized we had a feathered tyrannosaur,” Xu said. “Now, that was exciting.”