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Permian Period 二叠纪

译者: aquarius

299 Million to 251 Million Years Ago2.99亿年到2.51亿年以前
The Permian period, which ended in the largest mass extinction the Earth has ever known, began about 299 million years ago. The emerging supercontinent of Pangaea presented severe extremes of climate and environment due to its vast size. The south was cold and arid, with much of the region frozen under ice caps. Northern areas suffered increasingly from intense heat and great seasonal fluctuations between wet and dry conditions. The lush swamp forests of the Carboniferous were gradually replaced by conifers, seed ferns, and other drought-resistant plants.
二叠纪开始于2.99亿年前,并以地球上最大规模的物种灭绝而结束。那时,正在形成中的超级盘古大陆由于其巨大的面积给地球带来了气候剧变。南方干冷,大部分被冰冰盖笼罩。而北方经受着日益变暖而带来的气候变化,在旱季和雨季之间徘徊。石炭纪的葱翠的沼泽地正在慢慢被针叶林、种子蕨类以及其他抗干旱植物所代替。

Early reptiles were well placed to capitalize on the new environment. Shielded by their thicker, moisture-retaining skins, they moved in where amphibians had previously held sway. Over time, they became ideally suited to the desert-type habitats in which they thrive today.
早期的爬行动物非常适应这种新环境。它们厚厚的能保持水分的皮肤,使它们能取代以前这里的霸主两栖类动物。随着时间的推移,它们成了今天在沙漠地区最合适的居民。


Being cold-blooded, reptiles had to find ways to deal with big daily variations in temperature, from below freezing at night to over 100 degrees Fahrenheit (38 degrees Celsius) during the day. Some of the primitive pelycosaurs, which measured up to ten feet (three meters) long, had sail-like structures on their backs that are thought to have acted as heat exchangers, catching the sun in the morning to help warm the sluggish creatures.
由于是冷血动物,爬行类动物必须找到一个方法来对付这巨大的温差变化,这里的气温白天达30摄氏度以上,而晚上只有0度。原始盘龙类,大概有3米长,背上有长长的背鳍,这是它们的热交换器,可以在早上的时候从阳光获得能量来温暖它们自己。


Later, other mammal-like reptiles known as therapsids found an internal solution to keeping warm-scientists suspect they eventually became warm-blooded, conserving heat generated through the breakdown of food. These more metabolically active reptiles, which could survive the harsh interior regions of Pangaea, became the dominant land animals of the late Permian.
后来,类似于哺乳动物的兽孔类找到了一个通过自身来解决取暖的方法,就是通过消化食物来获得热能,科学家相信它们最后变成了热血动物。这些新陈代谢更活跃的爬行类,能够熬过盘古大陆上的恶劣环境并成了后期二叠纪上的霸主。


The therapsids flourished during the Permian, rapidly evolving many different forms, ranging from dinosaur-like fanged flesh-eaters to plodding herbivores. Some species reached a huge size, weighing in at over a ton. In the latter part of the Permian, smaller varieties emerged, likely warm-blooded and covered in insulating hair. From them, mammals would arise.
兽孔类在盘古大陆上日益兴盛,很快它们就发展成了各种形态,从类恐龙的食肉者到笨重的草食者。有一些个头很大,达到了一吨以上。在二叠纪后期,个头小热血的有皮毛的爬行类出现了,这其中就有以后的哺乳类。


The Permian seas came to be dominated by bony fishes with fan-shaped fins and thick, heavy scales. There were large reef communities that harbored squidlike nautiloids. Ammonoids, with their tightly coiled, spiral shells, are also widespread in the Permian fossil record.
二叠纪的海洋被硬骨鱼类统治着,它们有着扇子一样的鳍和厚厚的鳞片。海中还有大量像乌贼一样躲在礁石下软体动物。鹦鹉螺化石,这些螺旋状的贝壳,经常分布在二叠纪的化石群中。


Massive Loss of Life大灭绝


The Permian, however, represented the last gasp for much early prehistoric life. The period, and the Paleozoic era, came to a calamitous close 251 million years ago, marking a biological dividing line that few animals crossed. The Permian extinction-the worst extinction event in the planet's history-is estimated to have wiped out more than 90 percent of all marine species and 70 percent of land animals.
二叠纪代表了古生代的最后一个时期,在2.51亿年前走到了尽头,是当时绝大数生命的生死线,只有少数生命过了这道坎。二叠纪的生命大灭绝,是我们这个星球上最可怕的一次物种灭绝,海洋的90%的生命以及陆地上70%的生命都消失了。


Various theories seek to explain this mass extinction. Some scientists think a series of volcanic eruptions pumped so much debris into the atmosphere that the sun was blocked out, causing a significant drop in temperature and preventing plant photosynthesis, which in turn caused food chains to collapse.
对于这次大灭绝,有很多种解释。有的科学家认为是由于一系列的火山爆发导致火山灰进入大气层遮挡了太阳,气温急剧下降,植物无法进行光合作用,最终食物链崩塌的原因。


Other scientists point to global climate change, citing evidence for a period of sudden warming and cooling. These rapid extremes of conditions may have meant species were unable to adjust. Other theories include a catastrophic release of methane gas stored under the seabed, triggered by earthquakes or global warming, or a massive asteroid impact.
Perhaps a combination of factors was to blame. But whatever the cause, new animals and plants would evolve to fill the void. Not least among them: the dinosaurs.
也许是一大堆的原因导致了这次灭绝。但不管怎样,新的动物和植物会进化,而这其中,就有恐龙。

 

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