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Science & technology
科技板塊
Palaeontology
古生物學(xué)
Arctic dinosaurs
北極的恐龍
Dinosaurs once flourished near the North Pole
恐龍?jiān)?jīng)在北極附近繁盛
Most artistic impressions of dinosaurs picture them in lush forests or on vast temperate savannahs. That is fair enough. Such landscapes were common during the beasts' heydays, the Jurassic and Cretaceous periods. These pictures do, though, ignore the fact that dinosaur fossils have, for decades, been dug up in places which were at that time polar. Whether these are the remains of migrants which came for the summer, or of permanent residents, is debated. But a discovery of bone fragments and teeth from dinosaur hatchlings, just published in Current Biology by Patrick Druckenmiller of University of Alaska, Fairbanks, and his colleagues, suggests some dinosaurs did indeed make their full-time homes in the Arctic.
大多數(shù)關(guān)于恐龍的藝術(shù)印象都是在茂密的森林或廣闊的溫帶草原上。這很合理，因?yàn)檫@樣的景觀在侏羅紀(jì)和白堊紀(jì)的野獸鼎盛時(shí)期很常見(jiàn)。然而這些照片確實(shí)忽略了一個(gè)事實(shí)，即幾十年來(lái)恐龍化石都是在當(dāng)時(shí)的極地地區(qū)被挖掘出來(lái)的。不過(guò)這些遺骸究竟是夏天遷過(guò)來(lái)的移民的還是永久居民的則眾說(shuō)紛紜。而阿拉斯加大學(xué)費(fèi)爾班克斯分校的帕特里克·德魯肯米勒和他的同事們?cè)凇懂?dāng)代生物學(xué)》雜志上發(fā)表的一項(xiàng)發(fā)現(xiàn)表明，恐龍確實(shí)在北極安過(guò)家。
Modern animals that migrate to polar climes, notably birds, do often breed there. But their eggs hatch quickly and their young develop fast enough to fledge and fly to warmer places before winter arrives. Growth lines in fossilised dinosaur embryos found elsewhere suggest they needed as much as six or seven months of incubation before they were ready to hatch. Palaeontologists therefore reckon any discovery of fossilised eggs or hatchlings near the palaeo-poles would mean the species concerned must have been year-round residents rather than migrants.
遷徙到極地的現(xiàn)代動(dòng)物，特別是鳥類，通常會(huì)在那里繁殖。它們的卵孵化得很快，幼崽也發(fā)育得很快，能夠在冬天到來(lái)之前長(zhǎng)出羽毛飛到更溫暖的地方。在其他地方發(fā)現(xiàn)的恐龍胚胎化石中的生長(zhǎng)線表明它們需要6到7個(gè)月的孵化期才能孵化。因此古生物學(xué)家們認(rèn)為，任何在古極地附近發(fā)現(xiàn)的恐龍蛋或幼仔化石都意味著相關(guān)物種一定是永久居民而不是遷徙居民。
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