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The dramatic, age-related shift in plumage was noted in newly described fossils of Similicaudipteryx, a feathered creature that lived in what is now China about 125 million years ago. Xu and his colleagues analyzed two well preserved specimens of Similicaudipteyrx and report their findings in the April 29 Nature.
Both fossils are thought to come from juveniles because the vertebrae aren’t completely fused, which happens as animals reach adulthood, Xu says. In the larger and presumably older of the two specimens — a creature with an upper leg bone about 12 centimeters long and a body the size of a goose — the long feathers on the forelimbs and tail look just like modern bird feathers.
But in the pigeon-sized smaller creature, feathers on the forelimb and tail look modern only near their tips, Xu says. Closer to the body, those feathers have a ribbonlike shape but no central shaft — a type of structure previously seen in the tail feathers of some other Chinese feathered dinosaurs (SN: 12/9/2000, p. 374).
Unlike today’s birds, these dinosaurs changed the basic structure of their feathers some time during adolescence, says Xu, probably due to different timing and patterns of gene activity.
Palaeobiologists say that if the team's interpretation of the fossils is correct, it would be the first time that juvenile dinosaurs have been shown to have a different type of feather from adults. "Modern birds don't make such a transition," says Mike Benton from the University of Bristol, UK. Apart from the downy feathers of newborns, all later stages of modern birds are characterized by the same flight feathers. "This paper marks the first step in attempts to disentangle the evolution of developmental sequences among birds and their ancestors."
The fossils of the juvenile (left) and adult dinosaurs.Zheng Xiaoting.But some ornithologists and developmental biologists who study feathers question whether the younger fossil shows a ribbon-like feather or is instead from the bird's moulting phase. "Feathers are complicated," says ornithologist Richard Prum from Yale University in New Haven, Connecticut. When birds regenerate their feathers, the new ones grow rolled-up in a tube sheath. Prum says that the fossilized feathers of the younger dinosaur could be interpreted as a preserved image of feathers emerging from their sheath — like modern feathers in active moult.
Originally posted by Sinter Klaas
The live one on the hand. I mean.
Well... there are stories about surviving pteradactyl
T. rex ancestors were warm and fuzzy?
Article by: AMINA KHAN , Los Angeles Times Updated: April 4, 2012 - 11:09 PM
When it comes to dino outerwear, shag might be the new scales. Fossil evidence from a trio of 125-million-year-old dinosaurs that were relatives of Tyrannosaurus rex indicate the giant creatures had a fluffier side -- that they wore primitive feathers.
The three tyrannosauroids -- one adult and two juveniles -- belong to a newly described species discovered in northeastern China. The full-grown Yutyrannus huali weighed 3,000 pounds and stretched about 30 feet from nose to tail. The younger ones were still impressive at about 1,100 and 1,300 pounds. The fossils are described in Thursday's journal Nature.
The dinosaurs are noteworthy for being such complete specimens, scientists said. But the most eye-catching part of the find might well be the patchily preserved signs of fossilized feathers around different parts of the animals' bodies.
The feathers varied in length. Some on the tail were about 6 inches long; others, hanging from the neck, measured about 8 inches.