IN DAYS gone by, many palaeontologists thought the reason the dinosaurs became extinct was that the big, lumbering reptiles were outcompeted by small, nippy mammals who ate their eggs and generally ran rings around them. This quasi-anthropocentric view, of the inevitable rise of humanity’s ancestors, took a knock when closer examination showed that dinosaurs, too, were often nimble and warm-blooded. Then it was found that the extermination was an accident, caused when an asteroid hit the Earth. Until that moment, the dinosaurs had reigned supreme and mammals were just an afterthought.

过去,许多古生物学家认为恐龙灭绝的原因是,这种大型笨重的爬行动物被小巧的哺乳动物取代了,小巧的哺乳动物吃恐龙的蛋,一般绕着恐龙打转。这种准人类中心的观点,即人类祖先必然崛起的观点发生了动摇,最近的考察显示恐龙也很灵巧并且是恒温动物。然后人们发现灭绝是偶然的,是由小行星撞击地球引起的。直到灭绝的一刻,恐龙都有着至高无上的统治地位,哺乳动物只是后来的主宰。

Just how supreme is suggested by work carried out by Edward Simpson of Kutztown University in Pennsylvania and his colleagues. Dr Simpson’s analysis indicates that the relationship between dinosaurs and mammals was actually that of a diner to his lunch.

宾夕法尼亚库茨敦大学爱德华•辛普森和他的同事做的工作表明了(恐龙)到底有多么至高无上。辛普森博士的分析指出恐龙和哺乳动物之间的关系实际上就是用餐者和午餐的关系。

His study, just published in Geology, is of two burrows fossilised in sandstone near Escalante, Utah. The rock in question is 75m-80m years old: 10m-15m years older than the cataclysm that did for the dinosaurs. One burrow is 22cm (9 inches) long, 5cm wide and includes a 15cm-wide chamber. The other has a funnel-shaped opening that tapers down to a width of 5cm and runs towards what must once have been another opening. If these burrows had been made recently, they would instantly be recognisable as the work of small mammals. And that is exactly what Dr Simpson thinks they are.

他的研究刚发表在《地质学》上,是关于犹他州艾斯卡兰特附近的砂岩中两个石化的洞穴的。文中讨论的岩石石龄为7500-8000万年,比当时恐龙的大灾难时期早了1000-1500万年。一个洞穴22cm(9英寸)长,5cm宽,包括一个15cm宽的小室。另一个洞穴有个漏斗型开口,锥形向下至5cm的宽度,朝向曾经必是的另一个开口。如果这些洞穴是最近形成的,那么它们就会立刻被当作是小型哺乳动物的杰作。而辛普森博士认为这两个洞穴确实如此。

Which is interesting, but not extraordinary. Fossil teeth, and the occasional skeleton, show that small mammals were common at this time. That they should have lived in burrows is no surprise. But animals dig burrows for protection. The question is, from what was this protection sought?

这点令人感到有趣,但不特别。化石牙齿和偶尔发现的骨架显示小型哺乳动物在当时很普遍。它们应该住在洞穴中也不奇怪。但是动物掘洞是为了寻求保护。问题是,这种保护防的是谁?

The clue which Dr Simpson thinks answers this question is signs of digging near the burrows. When he and his colleagues analysed these scrapings they realised that their shape suggested they had been made by the claws of predatory, feathered dinosaurs related to a well-known species called Velociraptor. The claws of Velociraptor and its kin had hitherto been regarded as weapons to be deployed against beasts of the aggressor’s own size—either other Velociraptors, in fights over territory or mates, or. Dr Simpson’s work suggests the predators were not above going after small prey, too, just as coyotes will dig for prairie dogs.

辛普森博士认为回答这个问题的线索就是洞穴附近的挖掘迹象。在他和他的同事分析这些被刮削下的碎屑时,他们意思到抓痕的形状让人想到这些抓痕是由有羽毛的食肉恐龙的爪子造成的,这种有羽毛的食肉恐龙与众所周知的物种速龙有关。速龙及其亲属的爪子迄今仍被看作是撕裂侵略者自身大小的兽类的武器——也包括在争夺地盘和配偶或其它东西时撕裂其它速龙。辛普森博士的工作表明食肉动物也不是跟在小猎物之后追捕,而是象山狗挖洞找土拨鼠那样。

Dr Simpson and his colleagues reject alternative explanations—that the diggings might have been scrapes created by dinosaurs seeking to mark their territories, or perhaps to give themselves dust baths to help clean their feathers, as their relatives the birds do to this day. The digging, they think, is too deep for either of those explanations to make sense. It is possible that the dinosaurs’ intentions were to build nests for their eggs, but the researchers argue that this is unlikely because known nests are of a consistent size that does not match that of these diggings. What is left, then, is the likelihood that the dinosaurs were digging up snacks—hard as that thought may be for those snacks’ human descendants to digest.

辛普森博士和他的同事否决了另外的解释——发掘出的洞穴可能是恐龙企图标记自己的地盘制造的抓痕,或许是为了给自己来个尘浴清洁羽毛,正如它们的鸟类亲戚今天所做的。在他们看来,发掘出的洞穴太深了,那些解释的任何一种都说不通。也有可能是恐龙打算筑巢产恐龙蛋,但是研究人员辩解说,不象这回事,因为已知的蛋巢都大小恒定,跟这些发掘出的洞穴不相配。那么剩下的就是恐龙正在挖掘点心这种可能性了——尽管这个想法对那些点心的人类后裔来说可能难以消化。 更多信息请访问:http://www.24en.com/