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第三幕——继续生存

(2011-03-08 16:35:04)
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杂谈

Act III—Staying Alive

 

As earth rips apart at the dawn of the Cretaceous, a smorgasbord of features shows us natural selection at work in the dinosaurs. But with just a handful of bones to go on, it takes a lot of detective work to determine which features spell the difference between living another day and going the way of the dodo.

伴随着白垩纪初期大地的分离,许许多多不同的特征向我们展示了自然选择对恐龙的影响。但仅凭着手头这些恐龙骨骼化石,我们还要做大量的查证工作来确定,到底是哪些特征导致有些种类的恐龙可以以不同的方式生存了下来,而有些则走向灭绝。

 

Natural history stock, peacok, giraffes, elephants, whales, etc.

博物学资料,孔雀、长颈鹿、大象及鲸鱼,等等。

 

So paleobiologist Gregory Erickson takes a different tack, by looking at what modern animals, usually distant cousins of dinosaurs, are up to today. Greg can often be found sticking strange contraptions down the mouth of large reptiles in the name of science.

所以古生物学家格雷戈里·埃里克森采取了另一种方法。他研究现代动物,通常是恐龙的远亲,在今天是如何生存的。格雷格经常凭借科学研究,通过大型爬行动物的嘴设计出一些奇怪的装置。

 

Today, it’s a gharial crocodile…because its long thin snout bears a striking resemblance to Spinosaurus, perhaps the largest terrestrial carnivore ever to walk the earth - larger than T-rex. Fifty-seven feet long and up to nine tons, Spinosaurus started poking his head around the early Cretaceous some 100 million years ago. And Erickson wants to know how and what he ate.

今天,让我们来看看这只大鳄鱼,它那长而细的嘴与棘龙有着惊人的相似。棘龙也许是曾经在地球上出现过的最大的陆地食肉动物——比霸王龙还要大。五十七英尺长、重达九吨的棘龙在早期白垩纪,大约1亿年前便行走于这个星球之上。埃里克逊想知道它如何进食,都吃哪些东西。
 

How an animal puts food on the table is an important evolutionary pressure. Beneficial mutations here will almost surely stick, and the Cretaceous had its fair share of bizarre chomps as a result. Paul Sereno’s Nigersaurus sported a head shaped like a shovel and batteries of 600 needle-shaped teeth that earn him the nickname “The Lawnmower.” And Madagascar’s Masiakasaurus had teeth sticking straight out of his mouth…just right for nabbing snakes and fish.

动物如何进食是一项很重要的进化压力。在这里,朝着有利于生存的方向发生的变化几乎是确定无疑的,而且,在白垩纪存在许多具有奇特咀嚼方式的恐龙例子。保罗·塞利诺的尼日利亚龙向大家显示了一个有铁铲形状的头颅、几排600颗尖尖的牙齿的恐龙形象。这让它有了“剪草机”这样一个绰号。在马达加斯加发现的恶龙有向前倾的牙齿,很利于其捕捉蛇和鱼。
第三幕——继续生存

As for Spinosaurus, diet was just the tip of the evolutionary iceberg when it comes to this carnivorous curiosity.  Protruding down his back is a giant row of spikes - each as tall as six feet. Just what evolutionary niche they filled is up for debate - largely because no one has seen a Spinosaurus skeleton for the last 50 years, when it got lost amid the ruins of World War II.

说到棘龙,用什么方式进食有关这只食肉动物关于进化的冰山一角。沿着它突起的后背下来,是一排巨大的刺——每根都有六英尺长。但人们为它们到底填补了哪些进化中的空白仍争论不已——主要是因为人们已有50年未见过一只棘龙的骨骼化石。而已有的骨骼化石早已遗失在二战期间的废墟中了。


 

第三幕——继续生存

But when he saw surviving photos of it, paleontologist Josh Smith quickly surmised that the massive row of spikes on Spinosaurus’s back was the support system of some huge and intricate sail, an idea not without precedent. Half a world away in South America, Amargasaurus had two big rows of tall spines running from the top of his head down to the bottom of his back, and most likely supported a similar type of sail, which may have acted as a heat regulator, a display to tempt a mate or intimidate an enemy, perhaps all three.

但当古生物学家乔希·史密斯看到有关存留下来的棘龙照片后,他很快便推想出,在棘龙背上那排厚重的刺,是其巨大复杂的脊鳍的支撑系统。这种想法也是有先例的。在距离这里很远的南美洲,阿玛加龙有两排巨大高耸的刺,从其头部最顶端,一直长到后背的最底部,很像是在支撑着背鳍一样的东西。这种东西可用来调节身体热度,吸引异性的展示,或恐吓敌人,也许是三者兼有。

 

But after looking at much more recent animal skeletons, paleontologist Jack Baily of Ohio University ventures a very different theory. He says, it’s a hump. Not a water-storing hump like in a camel…but a frame-supporting like in a buffalo.

但在看过了大量近期发现的动物骨骼后,来自俄亥俄大学的古生物学家杰克·贝利大胆地提出了一个不同的理论。他说,它是一个峰。并不是像骆驼那样用来储水的驼峰,而是像野牛那样的支撑骨架的峰。

 

We compare the skeletons of the two animals and Baily states his case – that these  spikes  aren’t spikes but strong thick bones to support the massive back muscles of a hump.

我们对这两种动物的骨骼进行比较,贝利向我们讲述他的案例,这些刺其实并不是刺,而是用来支撑带有厚重肌肉的峰的坚实粗大的骨骼。 

 

Just goes to show, when it comes to dinosaurs – how they look and how they functioned is still a bit of a mystery. All we can do is venture the most educated of guesses.

让我们回到节目中来。对于恐龙到底长什么样以及它们是如何活动的,我们仍然不是很清楚。我们能做的,只是用已掌握的现有资料,再加上科学的分析进行猜测。

 

In one popular group of dinosaurs - the ceratopsians - the debates are coming to a head, literally. Triceratops is the most famous of these herding dinosaurs but as the continents continue their slow drift apart all different species evolved…all with their own Elizabethan-type frills and horns. There’s Styracosaurus, Centrosaurus, and Chasmosaurus - to name a few.

有关角龙类这一很活跃的恐龙群体的争论已经达到了顶点。当然了,你可以只按字面意思理解。三角龙是这类群居恐龙中最著名的,但随着大陆继续缓慢的分离漂移,所有不同的物种都在进化,都有着伊丽莎白时代样式的褶皱和角。比如戟龙,尖角龙和开角龙,等等。

 

Look at any of their skulls and it’s easy to understand why scientists always surmised a singular, high-impact use for these appendages – headbutting, big-horn sheep style. Mark Goodwin of UC-Berkeley used high-tech CT scanners to see if these bones could live up to the forces.

随便拿出任何一具这类恐龙的头骨化石,人们便不难理解为什么科学家们总是推想这就是一个用来冲撞的附件,好比大角羊那种风格的用头互抵。来自美国加州大学伯克利分校的马克·古德温用高科技CT扫描仪对这种头骨进行扫描,看看它们是否真的能承受人们推测的那种冲撞所产生的撞击力。


 

第三幕——继续生存

Goodwin takes us through CT scans and compares ceratopsian and sheep skulls to show they were not designed for the type of impact we’re used to seeing. Sheep have big hollow chambers to absorb impact like a motorcycle helmet…Triceratops was flat, which means high-impact crashes would not only break bones, they would result in some serious brain damage.

古德温让我们看CT扫描结果,用羊的头骨同角龙的进行比较。显示表明,角龙的角并不是像我们之前看到过的那种用来应对很强的冲击力的角。羊角有很大的中空的腔,可以起到像摩托车头盔那样吸收冲击力的作用。而三角龙的角确是扁平的,这就意味着强有力的冲撞不但会使骨头破裂,还有可能对它们造成严重的脑损伤。

 

    So if all this gear wasn’t for bumping heads, then what? We may find the answer in an Ohio freezer.
    如果这些东西不是用来冲撞的,那是用来干什么的呢?我们可以从一台俄亥俄州的制冷器中找到答案。

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