. .

Science & Technology
Feathered dinosaurs

No complete remains of a feathered dinosaur has ever been found

 May 07 - 13, 2001

Scientists have long argued the theory of where and who our present day birds evolved. Some believe it is from dinosaurs and some believe it was reptiles. Until now, no complete remains of a feathered dinosaur has ever been found. That fact has kept the argument alive. The recent discovery of a 130-million-year-old fossil of a feathered dinosaur has provided evidence that birds evolved from the ancient reptiles, according to new research published recently. Paleontologists at the American Museum of Natural History in New York, where the fossil on loan from China has gone on display, believe the skeleton of a young dinosaur covered with primitive fluff is proof that the creatures developed feathers for warmth, not flight, and that birds evolved from dinosaurs. Dr. Mark Norell, chairman of the division of paleontology, said that the fossil was about the size of a duck with a long tail. "It shows us that these creatures looked more like weird birds than giant lizards,'' he said. The fossil is 2.5 long and was found by farmers in layers of volcanic and sedimentary rock of the Yixian Formation in China's northeastern Liaoning Province. It is called a dromaeosaur which is a small, fast-running carnivorous dinosaur with a sickle-like claw on its middle toe. It is also said to be related to the tyrannosaurus rex, belonging to a group of dinosaurs called theropods. These are two legged predators with very sharp teeth. Norell said the most reasonable explanation for the feathers was not flight but warmth. "It's conceivable that smaller dinosaurs like this one and even the young of larger species like Tyrannosaurus rex may have needed feathers to keep warm,'' he said.

Feathered dinosaur fossils were first discovered in 1995 by Ji Qiang, of the Chinese Academy of Geological Science which lent the fossil to the New York museum, said the discovery was particularly important because it showed the feathers were attached to the dinosaur's body. "This is the specimen we've been waiting for. It makes it indisputable that a body covering similar to feathers was present in non-avian dinosaurs,'' he said in a statement. Theropod dinosaurs and birds share about 100 anatomical features, including a wishbone, swiveling wrists and three forward-pointing toes. Norell said dromaeosaurs were theropod dinosaurs thought to be most closely related to birds. Entombed in fine-grained rock, the dinosaur's unusually well-preserved skeleton resembles that of a duck with a reptilian tail, altogether about three feet in length. Its head and tail are edged with the imprint of downy fibers. The rest of the body, except for bare lower legs, shows distinct traces of tufts and filaments that appear to have been primitive feathers. On the backs of its short forelimbs are patterns of what look like modern bird feathers. This dinosaur's forelimbs were too short to have supported wings, Dr. Norell said in an interview, and so it was flightless. But some of its bone structure, notably the furcula, or wishbone, and the three forward-pointing toes, bears similarities to those of birds. Other recent discoveries of birdlike dinosaurs and dinosaurlike birds have encouraged support of the theory of a dinosaur-bird ancestral link.

A scientist who examined it last year in Beijing said he saw no evidence of feathers. "To me it's the best specimen yet showing that these structures are not feathers,'' said Storrs Olson, curator of birds at the National Museum of Natural History at the Smithsonian Institution."There's nothing there that has a structure like a feather.'' Olson said the feather-like covering could be many things, including impressions of decaying skin or feathery mineral crystals common to many fossils. He also questioned Norell's contention that the fossil supports the case that theropods pioneered feathers before ancient birds. Olson notes that finds of feathered theropods all appear younger than the earliest known bird, Archaeopteryx, which had highly advanced feathers.