A beautifully preserved fossil from southern Germany raises questions about how feathers evolved from dinosaurs to birds, two paleontologists argue in a study published Thursday.
The 150 million-year-old fossil is a juvenile carnivorous dinosaur about 2 1/2 feet long that scientists named Juravenator, for the Jura mountains where it was found.
It would have looked similar in life to the fleet-footed predators that menaced a young girl on the beach during the opening scene of "The Lost World," the second Jurassic Park movie.
The fossil”s exceptionally well-preserved bone structure clearly puts it among feathered kin on the dinosaur family tree. Because all of its close relatives are feathered, paleontologists would expect Juravenator to follow suit.
But a small patch of skin on the creature”s tail shows no sign of feathers. And the skin also doesn”t have the follicles that are typical of feathered dinosaurs, said Luis Chiappe, director of the Dinosaur Institute at the Natural History Museum of Los Angeles County. He and Ursula B. Gohlich of the University of Munich describe the fossil in Thursday”s issue of the journal Nature. 蘇州易優(yōu)閱讀寫作精華課，（tel:181-1815-9898）有趣、有用、提分快
"It has a typical scaly dinosaurian skin," Chiappe said.
The paleontologists believe Juravenator”s closest known relative may have been a fully feathered dinosaur from China, Sinosauropterix.
There are a number of possible explanations for Juravenator”s nakedness. Feathers could have been lost on the evolutionary line leading to Juravenator after arising in an ancestor to both it and its feathered relatives. Or feathers could have evolved more than once in dinosaurs, cropping up in sister species at different times and places. It is also possible that this particular fossil of Juravenator, which appears to be a juvenile, only grew feathers as an adult or lost its feathers for part of the year.
But there is another possibility as well, said Mark Norell, curator of paleontology at the American Museum of Natural History: It is entirely possible that Juravenator did have feathers, but they simply failed to fossilize.
"Feathers are really just difficult things to preserve," Norell said.
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To support his hypothesis he pointed out that several fossils of the oldest known bird, archaeopteryx, lack feathers.
Whether or not the new specimen raises interesting questions about how feathers — and thus birds — evolved, most experts do not see it as a challenge to the widely accepted view that modern birds are descended from dinosaurs.
恐龍化石有疑問古生物學(xué)家思索羽毛進(jìn)化過程
從體形龐大的恐龍到身材嬌小的鳥類，動(dòng)物 的羽毛是如何進(jìn)化的？在德國南部發(fā)現(xiàn)的一具保存完好的恐龍化石日前引起了古生物學(xué)家們對動(dòng)物 羽毛進(jìn)化過程的思考。
古生物學(xué)家聚焦恐龍羽毛
據(jù)美聯(lián)社3月15日報(bào)道，這具有1.5億年歷史的化石是一只大約2.5英尺長的幼年食肉恐龍留下來的，因?yàn)榘l(fā)現(xiàn)化石的地點(diǎn)位于侏羅山，因此科學(xué)家們稱它為Juravenator。
這具化石保存有異常完好的骨骼結(jié)構(gòu)，因此可以將其明確地歸入到恐龍家族中長有羽毛的一類。由于它所有的近親都長著羽毛，所以考古學(xué)家認(rèn)為Juravenator也是如此
