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Science and Technology
科技
Prehistoric reptiles
史前爬行動物
A loving mother
慈母
Family life in plesiosaurs
蛇頸龍的家族生活
THE Mesozoic land was dominated by dinosaurs.
中生代時期，恐龍統治著陸地。
At sea, though, the most abundant reptiles were the ichthyosaurs and plesiosaurs.
但是在海里，最繁盛的爬行動物要屬魚龍和蛇頸龍了。
Roughly speaking, these animals filled the ecological niches now occupied by toothed cetaceans such as dolphins and killer whales.
大致上講，這些動物填補了由現代齒鯨目動物海豚和虎鯨所占據的生態龕位。
Ichthyosaurs, indeed, looked somewhat like dolphins, though plesiosaurs—with their long necks and diamond-shaped paddles—were unlike anything now alive.
魚龍看上去的確有點象海豚，但擁有長頸和菱形鰭狀前肢的蛇頸龍卻與現存的任何動物不相類似。
Ichthyosaurs also resembled cetaceans in another way: unlike most living reptiles, which lay eggs, they gave birth to live young.
魚龍與鯨類動物還有另一點相似之處：大多數現存的爬行動物靠產卵繁殖，而魚龍是通過懷胎產子的。
For years, palaeontologists have wondered if the same was true of plesiosaurs.
數年來，古生物學家一直想知道蛇頸龍是否也通過懷胎方式繁殖后代。
Now they have found out that it was—but with an interesting twist.
如今他們證實了這一點——但卻是以一種有趣的方式。
Robin O'Keefe of Marshall University in West Virginia has analysed a plesiosaur fossil found in Kansas in 1987, which palaeontologists had suspected was a pregnant female about 4.7 metres (15 feet) long, but which had not been cleaned up and studied until last year.
西弗吉尼亞州馬歇爾大學的羅賓·奧基夫對1987年在堪薩斯州發現的蛇頸龍化石進行了分析。此前，古生物學家一直懷疑它是一條身長4.7米（15英寸）雌性懷孕蛇頸龍，但直到去年才將其清理和研究完畢。
As he reports in Science, he found an array of tiny bones, apparently belonging to a small specimen of the same species, in the fossil's abdominal cavity (see above; the extra bones are highlighted).
奧基夫在《科學》雜志報告中指出，在蛇頸龍化石腹腔內（額外的骨骼被高亮顯示）發現了一些小骨骼陣列，它們顯然是屬于同類物種的小標本。
It is unlikely that these were the remains of a meal because the bones are not broken down in the way that would be expected if they were partly digested.
這些小骨骼不可能是食物的殘渣，因為如果它們是被部份消化的其它動物的骨骼，那么它們的斷裂方式應該研究人員所預想的方式相同，但結果卻不是。
Instead, Dr O'Keefe believes he has discovered evidence that plesiosaurs, too, gave birth to live young.
反過來，奧基夫博士相信他已發現了蛇頸龍同樣靠胎生繁殖的證據。
What is more, all the baby bones come from a single individual, estimated to have been 1.5 metres long.
此外，所有幼蛇頸龍的骨骼皆來自于單一的個體，身長估計有1.5米。
Ichthyosaurs and other contemporary viviparous species, by contrast, gave birth to multiple offspring.
對比之下，魚龍和其它現代胎生物種可以生育多個后代。
The fetus's level of development indicates that it was at most two-thirds mature.
從蛇頸龍幼胎的發育水平來看，它最多有三分之二的成熟度。
Had it survived to birth it would have been about 1.8 metres in length, and about one and a half times as heavy (relative to parental weight) as the offspring of other viviparous species of the time.
如真能夠成功分娩，幼蛇頸龍的身長可能為1.8米左右，體重大約是同時期其它胎生物種后代的1.5倍（相對于父母的重量）。
That it was so heavy, and also alone, is of great interest.
蛇頸龍幼胎超重且單獨的個體引起了古生物學家的極大興趣。
Georges Cuvier, an early palaeontologist, made his reputation by predicting the anatomies of newly discovered fossil species from scant evidence, such as single bones.
早期古生物學家喬治·居維葉能在實據不足的情況下（如單一的骨骼）預測出新發現的化石物種的軀干結構，這使他在業界聲名顯著。
He did so by applying to fossils the principles of comparative anatomy, asking what light the body shapes of living animals could cast on the shapes of creatures from the past.
之所以能做到這點是因為他將對比解剖學的規則應用于化石樣本并探尋現存動物的體形對古代動物的體形有什么樣的啟發借鑒作用。
Many modern palaeontologists try to do something similar, except that what they reconstruct is behaviour.
許多現代古生物學家除了重現古代動物的行為外，也在嘗試做著同樣的事情。
Dr O'Keefe has performed such an analysis on his find.
奧基夫博士已將這種分析應用于他的發現。
He starts from a fundamental observation about reproduction: you can go for quantity or quality.
他的實驗開始于對繁殖現象的基本觀察：你能選擇數量或質量。
Having one child at a time is the ultimate expression of quality.
每次只生育一胎是追求質量的最終體現。
It implies huge parental investment in the offspring since, if you lose it, you lose everything.
它意味著父母在后代身上的巨大投入，一旦失去了這個幼子也就等于失去了一切。
Often, too, it implies membership of a social group, within which favours can be traded to spread the load of parenthood.
它也常常意味著社會群體的成員身份，在這個社會群體中，幼子關愛可以通過利益交換得到以減輕父母的負擔。
Most speculatively, it might even imply a degree of intelligence—for the most intelligent mammals and birds are generally those that live in groups.
從最大程度上猜測，它甚至可能意味著動物的智商程度——生活在群體中的哺乳動物和鳥類通常是最聰明的。
All this is a lot to load on a single fossil, of course.
當然僅憑這個單一化石，古生物學家未免猜想得太多了。
But it would make sense.
但它卻能夠說明問題。
It would mean plesiosaurs not only occupied a similar ecological niche to whales, but behaved like them, too.
它將意味著蛇頸龍不僅占據著與鯨魚相似的生態龕位，其行為方式也與鯨魚相仿。
