时间:2019年10月20日 18:56:13

And fishing can be dangerous. A southern sea lion. It uses the speed of a breaking wave to catch up the gentoos. Sea lions normally eat fish. So he is used to catching stream-line swimmers. But the gentoos seem more than his match-up at sea. He must change tactics. Perhaps it would be easier in the shallows. But, no, it seems penguins are uncatchable in water. How about on land? The penguins wings are so powerful for swimming, but of no help when it comes to running. Now surely the sea lion has a chance. But on the beach both are like fish out of water. Rarely do hunter unhunted play their roles with so little skill. The outcome is anyones guess.无疑异常危险。南方的海狮用其无与伦比的速度追上了巴布亚企鹅。海狮通常吃鱼。所以他会捕捉流线型的游泳者。但是巴布亚企鹅似乎更符合其要求。他必须改变战术。也许在浅滩会比较容易。但是,不,看情况企鹅是在水里是不可能被抓住的。但在陆地上会如何呢?企鹅的翅膀看似就是天生为游泳而准备,但它在跑的时候却根本不起一点作用。现在机会降临到了这只海狮身上。但在地面上都喜欢离开水的鱼。很少有猎人不用一点点技巧打猎。结果则仁者见仁,智者见智。注:听力文本来源于普特201202/169943

Science and Technolgy科技What dinosaurs ate恐龙吃什么The belly of the beast腹中发现A chance discovery from China suggests some dinosaurs lived in trees在中国的一次偶然发现暗示着有些恐龙在树上生活WHAT dinosaurs ate is, of course, a question as interesting and illuminating as what ate dinosaurs (see article).恐龙吃什么?当然,这个问题与“什么吃恐龙?”一样有趣,一样具有启发性。In the case of one particular dinosaur,Microraptor, the matter was addressed in a presentation to the annual meeting of the Society of Vertebrate Palaeontology by Jingmai OConnor of the Institute of Vertebrate Palaeontology and Palaeoanthropology, in Beijing.但就“小盗龙吃什么”这一问题(见文章),北京中国科学院古脊椎动物和古人类研究所的Jingmai OConnor在古脊椎动物学会年会上发表了演说。Microraptor (see photograph) is one of many small, feathered dinosaurs found in what is now China that were alive during the Cretaceous period more than 66m years ago.小盗龙(见图),生活在距今六千六百多万年前的白垩纪,是现今中国境内发现的众多体型娇小、长有羽毛的恐龙之一。Being feathered, it and its kind were cousins to birds.这一种恐龙身着羽毛,是鸟类的近亲。The actual split between the two groups, though, had happened much earlier, during the Jurassic period (the first known bird is Archaeopteryx, from 150m years ago), and by the late Cretaceous there were many species of bird around.尽管,这两种物种早在侏罗纪时期(已知的最早鸟类是始祖鸟,生活在一亿五千万年前)就已分道扬镳,而且,到了白垩纪后期,已出现了许多种的鸟类。What Dr OConnor and her colleagues have found is the remains of one of those birds, of an as-yet-unidentified species, in the stomach of a specimen of Microraptor.OConnor士和她同事在小盗龙样本的胃中发现了那时期鸟类的残骸,但其种类还未得到鉴别。That is interesting. Discovering direct evidence of what a fossil animal ate, rather than having to infer it from details such as the shape of its teeth, is always valuable.比起根据其牙齿形状等细节来推测出结果,找出古生物吃什么的直接据是有价值的。But the finds true significance is a small detail of the preys anatomy: the third toe of its foot.但是,这个发现真正重要之处却是其骨骼的一个细微之处:它脚掌的第三个脚趾。那是非常有趣的。The size of the preys third toe is important because, among birds, long third toes are helpful for grasping branches and perching in trees.捕食者第三个脚趾的大小是很重要的,因为,对于鸟来说,长长的第三趾可以帮助其抓紧树枝,在树上栖息。Indeed, the trait is so useful for arboreal life that it is used by many avian palaeontologists to decide whether newly excavated species of fossil birds lived in trees or on the ground.的确,对于树栖生物这一特点是相当有用的,而许多鸟类古生物学家也利用这一特点来确定新挖掘出的鸟类化石是栖息在树上还是生活在地面上。And the last meal of this particular specimen of Microraptor did, indeed, have a long third toe.而小盗龙的最后一餐显然长有长长的第三个脚趾。That elongated toe suggests to Dr OConnor that Microraptor, too, was arboreal, and hints that its feathers may have helped it to move through an environment where hops, jumps and flaps between branches were a regular part of its daily activity.那细长的脚趾暗示着OConnor士小盗龙也是树栖的。在一个需在枝桠间跳跃、滑行的生活环境中,它的羽毛可能对它的日常活动有所帮助。Whether the first birds evolved from arboreal or terrestrial ancestors is a matter of lively debate among palaeontologists.关于第一只鸟是从树栖还是陆生的祖先进化而来,一直是古生物学家激烈争论的话题。A fossil formed so long after birds emerged does not, in truth, shed much light on that debate.事实上,一个在鸟类出现很久之后形成的化石并没有使得这一论战明朗化。But it does suggest feathers may have helped promote life in the trees, even for creatures that could not actually fly.但是,这的确说明对于居于树上、即使是那些根本不能飞的树栖生物来说,羽毛可能真的有助于它们的生活。 /201210/206472

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