On October 6, 2004, scientists announced the discovery a tiny, earlier cousin of Tyrannosaurus rex.   What made it unique was a partial coat of hair-like feathers.  Xu Xing of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, is the lead author of the new paper. He said his discovery is significant because it sheds light on the evolution of tyrannosaurids, which include the giant carnivore T. rex.  "With this new find, we can see a perfect evolutionary transition from typical coelurosaurians to highly specialized large tyrannosaurids and clarify a number of questions," he said.
    The description of Dilong paradoxus is based on the fossils of four specimens, including a fragmented one with evidence of protofeathers - precursors to the feathers found on modern birds. The fragmented fossil went unidentified until a more complete fossil of the same creature was studied and found to match the morphology, or form and structure, of that found in the earlier fragments. The fossils come from a geologic feature in northeastern China known as the Yixian formation, which has yielded several other feathered dinosaurs.
    Mark Norell, a curator and chair of the division of paleontology at New York's American Museum of Natural History, co-authored the paper that describes the new species, which appeared in the science journal Nature.  Norell said the discovery supports theories that dinosaurs were birdlike, warm-blooded creatures that evolved feathers to stay warm - not to fly.   "It's the kind of thing we expected, but we thought we might never find a fossil that would justifiably show it."  Xu added that even large dinosaurs like T. rex may have had feathers when they were young. "They are not likely to be completely featherless animals for [their] whole life."
    Thomas Holtz, a vertebrate paleontologist at the University of Maryland in College Park, was among the group of paleontologists to predict that early tyrannosaurids had feathers. The scientist, who was not involved in the study, said he is thrilled at the latest find.  "There is a lot of attention given to surprises in paleontology," he said. "But there is a side to it where we hope to be scientists, and part of science is based on predictions that are based on the best evidence at hand. It helps to see predictions pan out with discoveries."  The predictions Holtz and other paleontologists have made are based on skeletal data that suggest tyrannosaurids had a more recent common ancestor with birds than did Sinosauropteryx, the most primitive known feathered dinosaur. Sinosauropteryx lived 120 to 150 million years ago.
     Hans-Dieter Sues, the associate director for research and collections at the Smithsonian Institution's National Museum of Natural History in Washington, D.C., agrees. "The new small tyrannosaur definitely shows an interesting mosaic of primitive and derived features; its skull is already more like that of other, later tyrannosaurs than the rest of its skeleton," said Sues, who is a member of the National Geographic Society's Committee for Research and Exploration.

A footnote:

    Our knowledge of prehistoric life is expanding at an ever-increasing rate.  This discovery made us aware of just how rapid it is.  Only one week prior to this discovery we printed our Feathered Dinosaurs poster.  It originally contained an inset that explored the possibility that tyrannosaurs had feathers, but at the last minute, we discovered the research on brooding dinosaurs.  We felt it was more appropriate to the poster so we created an inset covering the topic and it replaced the one exploring feathered dinosaurs.  Information on Dilong will be incorporated into the next edition.