PARIS: A team led by the world's most successful fossil hunter said that they have found the remains of a feathery dragon-like forerunner of the mighty Tyrannosaurus rex at a dinosaur graveyard in northeastern China.

The "surprising" creature is a tyrannosaurid that lived between 139 million and 128 million years ago, the researchers led by Xu Xing of the Institute of Vertebrate Palaeontology and Palaeoanthropology report on Thursday.

Small and slender, measuring about 5.2 feet from tip to tail, the creature had the characteristic two powerful rear feet and flesh-ripping teeth made famous by the T Rex, whose 20-million-year reign ended with the twilight of the dinosaurs some 65 million years ago.

But it had several big differences -- it had relatively long arms compared to its big descendant, as well as a long, dragon-like snout, and its scaly skin was covered with a fibrous coat.

Dinosaurs that are believed to have been the ancestors of modern birds had primitive feathery coverings like this.

But in this case, the purpose of the covering was not to provide an evolutionary step for flight but a means to keep warm, the authors suggest.

"This is the first direct fossil evidence that tyrannosaurids had protofeathers," their study, published in the weekly British scientific journal Nature says.

The discovery has been called Dilong paradoxus. The first word is a composite of the Chinese "di" (emperor) and "long" (dragon), while the second "refers to the surprising characters of this animal," the study says.