A newly described relative ofTyrannosaurus rexis the largest known feathered animal - living or extinct.
The feathered meat-eating dinosaur lived about 125 million years ago and is estimated to have weighed a whopping 1,400kg as an adult.
The new species, known asYutyrannus, has been identified from three fossils found in north-eastern China.
The finds, detailed in Nature journal, challenge current theories about the evolution ofT.rexand its relations.
This group of dinosaurs is known as the Tyrannosauroids.
Tyrannosaurus rexand its gigantic cousins lived until around 65 million years ago - when a huge asteroid wiped out the dinosaurs - but most of their earlier relatives are thought to have been much smaller.
Fine feathered fiend
However, Xing Xu and colleagues from the Chinese Academy of Sciences in Beijing have now described three specimens ofYutyrannus, which represents an early example of the Tyrannosauroid form.
The fossils include the one-and-a-half-tonne adult and also two juvenile specimens that would have tipped the scales at about half a tonne.
The dinosaur, whose name translates as "beautiful feathered tyrant", shares some features with later tyrannosaurs likeT.rex, but has three functional fingers (where T. rex had two) and a foot typical of other early tyrannosaur relatives.
Perhaps the most notable discovery, however, is the creature's extensive plumage, which provides direct evidence for the existence of giant feathered dinosaurs.
The scientists think the long, filament-like feathers would have acted as insulation, but they cannot rule out the possibility that they were also used for display in mating or fighting rituals.