Tue, Apr 26, 2011 page14

• Night-vision let dinosaurs stalk prey by dark: study 新論證：恐龍具暗夜跟蹤獵物的夜視能力

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  Ferocious, meat-eating dinosaurs were equipped with night vision that helped them stalk their prey in the dark, according to a study published on April 14 in the journal Science.

  Plant-eating dinosaurs could also see a fair bit at night, because they likely had to eat round the clock to keep their bellies satisfied, while flying dinosaurs, like birds, were active only during the day, said the study.

  Researchers at the University of California, Davis, were able to make these judgments by studying the eye area of fossilized dinosaurs.

  

  This image shows the skeleton of the nocturnal flyer Ctenochasma elegans, a pterosaur. 這張圖像是夜間飛行纖弱梳頜翼龍的骨骼標本。

  Photo: AFP / Lars Schmitz
  照片：法新社／拉爾斯‧施米茨

  By taking measurements of the bony circle called the “scleral ring” in their eye and comparing it to the eye socket size in 164 living lizards and birds as well as 33 dinosaur fossils, scientists could tell which ones saw in the dark.

  Animals that are mainly active by day have a smaller opening in the scleral ring, while nocturnal creatures had a much larger opening, said the study. Those who roamed day and night fell somewhere in between.

  Early birds and flying dinos known as pterosaurs were mostly daytime hunters, according to their eye measurements.

  Velociraptors, the type featured in the movie “Jurassic Park,” were likely night-stalkers.

  Scientists could not say the same about the massive meat-gnashing Tyrannosaurus rex however, because they didn’t have any well-preserved eye fossils of theirs to examine.

  The study counters the widely held belief that most dinosaurs hunted by day while smaller mammals roamed at night.

  “It was a surprise, but it makes sense,” said co-author Ryosuke Motani, professor of geology at UC Davis.

  (AFP)

  根據一項發表於《科學》期刊的研究，兇猛的肉食性恐龍具有夜視能力，能幫助牠們在黑暗中跟蹤獵物。

  這篇研究指出，草食性恐龍因為必須日夜不停地飲食以填飽肚子，可能在夜晚也能看得到一點東西。但像鳥類等飛行恐龍就只在白天活動。

  加州大學戴維斯分校的研究員從變成化石的恐龍眼部骨骼，作出這些判讀。

  藉由測量恐龍眼部稱為鞏膜環的環狀骨骼大小，然後與現存的一百六十四種蜥蜴、鳥類，還有三十三種恐龍化石比較後，科學家就能分辨哪一些擁有夜視能力。

  研究發現，通常活躍於白晝的動物，其鞏膜環開口較小，而夜行動物的開口則大得多。至於晝夜皆活動的動物則開口大小介在兩者之間。

  根據眼眶的量測，早期鳥類與被稱為翼龍的飛行恐龍大部分是白晝的獵獸。

  在電影「侏儸紀公園」裡出現的迅猛龍，可能是夜間獵物跟蹤者。

  科學家現在還不知道張牙舞爪的超大肉食性暴龍，是否也能在夜間覓食，因為保存下來的暴龍眼部化石都不夠完整，無法研究。

  這項說法與傳統看法相左，過去研究認為，多數恐龍在白天狩獵，小型哺乳類在夜間活動。

  此研究的合著者，同時也是加州大學戴維斯分校地質系教授Ryosuke Motani說，「這項發現雖令人驚奇，不過說得通。」

  （法新社／翻譯：林亞蒂）

  For your information

  TODAY’S WORDS 今日單字

  1. night vision n. phr. 夜視 (ye4 shi4) 例: Because humans have poor night vision, there are special kinds of glasses helping us see in the dark. (因為人類夜視能力差，坊間有特殊的眼鏡輔助我們的夜視能力。) 2. fossilize v. 變成化石 (bian4 cheng2 hua4 shi2) 例: We know a lot about dinosaurs because many of them have been fossilized, or turned into stone. (我們知道許多有關恐龍的事情，因為多數已經變成化石，或是變成石頭。) 3. night-stalker n. phr. 夜間跟蹤者 (ye4 jian1 gen1 zong1 zhe3) 例: You shouldn’t walk alone at night because if you’re not lucky, you could be attacked by a night-stalker looking for someone to rob. (你不應該在夜晚獨自行走，若你運氣不好，你可能會被伺機找人搶劫的夜間跟蹤者攻擊。)
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