Remember the tooth

　　齒狀物所記

　　A link is made in an ancient ecosystem

　　古生態系統的一環

　　WHO ate whom in the food chains of the past is rarely clear.

　　過去的食物鏈中誰吃誰的問題很少能明確下來。盡管哪些物種是捕食者，

　　Though it is obvious which species were predators and which prey,

　　而哪些物種又是被掠食者顯而易見，

　　the subtle specialisations of feeding habit that allow many types of carnivore to co-existare rarely preserved in the fossil record.

　　但是讓多種類型的肉食性動物共存的攝食習性的微妙法門卻很少在化石記錄中保存下來。

　　Rarely, but not never.

　　很少，不等于永遠都沒有。

　　That is why the recent discovery of a Jurassic ammonite with a shark s tooth embedded inits shell has excited palaeontologists.

　　這正是最近發現的一枚外殼中嵌有鯊魚齒狀物的侏羅紀鸚鵡螺化石令古生物學家興奮的原因所在。

　　The ammonite in question, Orthaspidoceras, a species that thrived 155m years ago,

　　在1.55億年前古鸚鵡螺是非常繁盛的物種，

　　was part of the collection of an amateur who did not realise the significance of what he hadfound.

　　討論中的這枚鸚鵡螺化石是一個業余收藏家的收藏部分，這位收藏家沒有意識到它的重大意義。

　　Romain Vullo of the University of Rennes,

　　然而，雷恩大學的羅曼?武洛意識到了，

　　however, didand he has brought the discovery to the attention of the scientific world in thepages of Naturwissenschaften.

　　而且他已經借《自然科學》雜志成功地讓這個發現受到科學界的注意。

　　Ammonites were both predators and prey.

　　古鸚鵡螺既是捕食者又是被掠食者。

　　They occupied a position in the Mesozoic oceans similar to that of modern squid.

　　他們在中生代海洋中占有一席之地，類似于現代的魷魚。

　　Like squid, they were swimming tentacled molluscsa group called the cephalopods.

　　它們象魷魚一樣是游動的觸手軟體動物，這類軟體動物被稱為頭足類動物。

　　Unlike squid, though, they had protective shells.

　　不過，它們不象魷魚，它們有起保護作用的殼。

　　These shells were divided internally into gas-filled chambers.

　　這些殼的內部劃分成許多充氣室。

　　The result had neutral buoyancy, allowing the animal to move by jet propulsion.

　　結果形成中和浮力，使動物能夠借助噴氣推進移動。

　　Modern pearly nautiluses, whose relationship to ammonites is much debated, have a similararrangement.

　　現代的珍珠鸚鵡螺與古鸚鵡螺的關系備受爭議，但它也有類似的結構安排。

　　What ammonitesor, at least, some of themate became clear earlier this year when anX-ray showed a small crustacean in the jaws of a species called Baculites.

　　古鸚鵡螺以什么為食在今年早些時候終于搞清楚了，X光顯示了一個被稱為Baculites物種的下頜，證明是小甲殼類動物。

　　But what ate ammonites has never been shown in such an unambiguous manner.

　　但是，人們還從來沒有以這樣一種毫不含糊的方式證明什么動物以古鸚鵡螺為食。

　　Some ammonite fossils have tooth marks that look as though they were made by hugereptilian predators called mosasaurs.

　　有些鸚鵡螺化石上的齒痕看起來好像是由巨大的爬蟲類捕食者滄龍留下的。

　　Some appear to have been attacked by the beaks of other cephalopods.

　　有些看來像是其它頭足類動物的嘴襲擊過的痕跡。

　　And some seem to have been bitten by sharks.

　　有些似乎是被鯊魚咬傷的。

　　On top of that, coprolites, as palaeontologists politely describe fossil faeces, have turned upwith ammonite shells in them.

　　除此之外，被古生物學家委婉地形容成糞化石的糞便化石中也找到了古鸚鵡螺的殼。

　　Based on comparisons with modern evacua, these are probably from sharks.

　　根據與現代的排泄物相比較，這些化石可能都來自鯊魚。

　　But which sharks?

　　但是是哪種鯊魚呢?

　　Dr Vullo s ammonite nails one culprit.

　　武洛博士的鸚鵡螺化石鎖定了一個罪魁禍首。

　　The tooth belongs to a species called Planohybodus.

　　這顆齒狀物屬于一個被稱作Planohybodus的物種。

　　And that is a surprise.

　　這是一個驚喜。

　　Those modern sharks that eat shelled animals have robust teeth for crunching through hardexteriors.

　　以有殼動物為食的那些現代鯊魚都長著堅固耐用的牙齒，以便咬碎食物堅硬的外殼。

　　The teeth of Planohybodus, in contrast, were slender and pointedthe sort usuallyassociated with grasping and tearing at flesh.

　　相反，Planohybodus的牙齒細長而尖銳，就是通常讓人聯想到抓住并撕咬肉類的那種。

　　In a modern predator, that would indicate the habit of eating fish.

　　這可能意味著現代肉食動物有吃魚的習慣。

　　That a shark with teeth like this would try to make a meal of an ammonite is, at first sight,odd.

　　長有這種牙齒的鯊魚想吃掉古鸚鵡螺，乍一看太奇怪了。

　　But second thoughts provide a possible explanation.

　　但再三考慮就會想到一個可能的解釋。

　　Ammonites manoeuvrability would have depended crucially on their buoyancy control.

　　古鸚鵡螺的靈活性關鍵取決于其浮力控制。

　　Even a small puncture to the shell, which a pointed tooth would be well able to deliver,

　　即使在其外殼上有一個小小的穿刺，這點尖尖的牙齒駕輕就熟，

　　would let the water in and cause that control to vanish.

　　也會讓水滲入，造成浮力控制的消失。

　　Since ammonites could not withdraw entirely into their shells for self-defence,

　　由于古鸚鵡螺不能完全縮回殼內自衛，那么就剩一個問題了，

　　it would then just be a question of dragging the creature out of its chamber in order to eat it.

　　即為了吃掉它而把這種動物從殼腔內拽出來。

　　And for that, sharp, pointed teeth are ideal.

　　對于這點，銳利的尖尖牙齒就十分理想了。

　　詞語解釋

　　1.ecosystem n.生態系統

　　Water is the core of a healthy ecosystem.

　　水是維持生態系統良性循環的根本。

　　2.predator n.食肉動物;掠奪者

　　Young birds are very vulnerable to predators.

　　幼小的鳥易受食肉動物傷害。

　　3.prey n.犧牲者;被掠食者

　　She was easy prey for dishonest salesmen.

　　她很容易地讓奸商敲了竹杠。

　　4.specialisation n.專門;專業化

　　Innovation and specialisation are more important.

　　創新和專業化更為重要。

　　5.preserve v.保護;保存;保持

　　It is highly important to preserve the environment.

　　保護自然環境至關重要。

　　Remember the tooth

　　齒狀物所記

　　A link is made in an ancient ecosystem

　　古生態系統的一環

　　WHO ate whom in the food chains of the past is rarely clear.

　　過去的食物鏈中誰吃誰的問題很少能明確下來。盡管哪些物種是捕食者，

　　Though it is obvious which species were predators and which prey,

　　而哪些物種又是被掠食者顯而易見，

　　the subtle specialisations of feeding habit that allow many types of carnivore to co-existare rarely preserved in the fossil record.

　　但是讓多種類型的肉食性動物共存的攝食習性的微妙法門卻很少在化石記錄中保存下來。

　　Rarely, but not never.

　　很少，不等于永遠都沒有。

　　That is why the recent discovery of a Jurassic ammonite with a shark s tooth embedded inits shell has excited palaeontologists.

　　這正是最近發現的一枚外殼中嵌有鯊魚齒狀物的侏羅紀鸚鵡螺化石令古生物學家興奮的原因所在。

　　The ammonite in question, Orthaspidoceras, a species that thrived 155m years ago,

　　在1.55億年前古鸚鵡螺是非常繁盛的物種，

　　was part of the collection of an amateur who did not realise the significance of what he hadfound.

　　討論中的這枚鸚鵡螺化石是一個業余收藏家的收藏部分，這位收藏家沒有意識到它的重大意義。

　　Romain Vullo of the University of Rennes,

　　然而，雷恩大學的羅曼?武洛意識到了，

　　however, didand he has brought the discovery to the attention of the scientific world in thepages of Naturwissenschaften.

　　而且他已經借《自然科學》雜志成功地讓這個發現受到科學界的注意。

　　Ammonites were both predators and prey.

　　古鸚鵡螺既是捕食者又是被掠食者。

　　They occupied a position in the Mesozoic oceans similar to that of modern squid.

　　他們在中生代海洋中占有一席之地，類似于現代的魷魚。

　　Like squid, they were swimming tentacled molluscsa group called the cephalopods.

　　它們象魷魚一樣是游動的觸手軟體動物，這類軟體動物被稱為頭足類動物。

　　Unlike squid, though, they had protective shells.

　　不過，它們不象魷魚，它們有起保護作用的殼。

　　These shells were divided internally into gas-filled chambers.

　　這些殼的內部劃分成許多充氣室。

　　The result had neutral buoyancy, allowing the animal to move by jet propulsion.

　　結果形成中和浮力，使動物能夠借助噴氣推進移動。

　　Modern pearly nautiluses, whose relationship to ammonites is much debated, have a similararrangement.

　　現代的珍珠鸚鵡螺與古鸚鵡螺的關系備受爭議，但它也有類似的結構安排。

　　What ammonitesor, at least, some of themate became clear earlier this year when anX-ray showed a small crustacean in the jaws of a species called Baculites.

　　古鸚鵡螺以什么為食在今年早些時候終于搞清楚了，X光顯示了一個被稱為Baculites物種的下頜，證明是小甲殼類動物。

　　But what ate ammonites has never been shown in such an unambiguous manner.

　　但是，人們還從來沒有以這樣一種毫不含糊的方式證明什么動物以古鸚鵡螺為食。

　　Some ammonite fossils have tooth marks that look as though they were made by hugereptilian predators called mosasaurs.

　　有些鸚鵡螺化石上的齒痕看起來好像是由巨大的爬蟲類捕食者滄龍留下的。

　　Some appear to have been attacked by the beaks of other cephalopods.

　　有些看來像是其它頭足類動物的嘴襲擊過的痕跡。

　　And some seem to have been bitten by sharks.

　　有些似乎是被鯊魚咬傷的。

　　On top of that, coprolites, as palaeontologists politely describe fossil faeces, have turned upwith ammonite shells in them.

　　除此之外，被古生物學家委婉地形容成糞化石的糞便化石中也找到了古鸚鵡螺的殼。

　　Based on comparisons with modern evacua, these are probably from sharks.

　　根據與現代的排泄物相比較，這些化石可能都來自鯊魚。

　　But which sharks?

　　但是是哪種鯊魚呢?

　　Dr Vullo s ammonite nails one culprit.

　　武洛博士的鸚鵡螺化石鎖定了一個罪魁禍首。

　　The tooth belongs to a species called Planohybodus.

　　這顆齒狀物屬于一個被稱作Planohybodus的物種。

　　And that is a surprise.

　　這是一個驚喜。

　　Those modern sharks that eat shelled animals have robust teeth for crunching through hardexteriors.

　　以有殼動物為食的那些現代鯊魚都長著堅固耐用的牙齒，以便咬碎食物堅硬的外殼。

　　The teeth of Planohybodus, in contrast, were slender and pointedthe sort usuallyassociated with grasping and tearing at flesh.

　　相反，Planohybodus的牙齒細長而尖銳，就是通常讓人聯想到抓住并撕咬肉類的那種。

　　In a modern predator, that would indicate the habit of eating fish.

　　這可能意味著現代肉食動物有吃魚的習慣。

　　That a shark with teeth like this would try to make a meal of an ammonite is, at first sight,odd.

　　長有這種牙齒的鯊魚想吃掉古鸚鵡螺，乍一看太奇怪了。

　　But second thoughts provide a possible explanation.

　　但再三考慮就會想到一個可能的解釋。

　　Ammonites manoeuvrability would have depended crucially on their buoyancy control.

　　古鸚鵡螺的靈活性關鍵取決于其浮力控制。

　　Even a small puncture to the shell, which a pointed tooth would be well able to deliver,

　　即使在其外殼上有一個小小的穿刺，這點尖尖的牙齒駕輕就熟，

　　would let the water in and cause that control to vanish.

　　也會讓水滲入，造成浮力控制的消失。

　　Since ammonites could not withdraw entirely into their shells for self-defence,

　　由于古鸚鵡螺不能完全縮回殼內自衛，那么就剩一個問題了，

　　it would then just be a question of dragging the creature out of its chamber in order to eat it.

　　即為了吃掉它而把這種動物從殼腔內拽出來。

　　And for that, sharp, pointed teeth are ideal.

　　對于這點，銳利的尖尖牙齒就十分理想了。

　　詞語解釋

　　1.ecosystem n.生態系統

　　Water is the core of a healthy ecosystem.

　　水是維持生態系統良性循環的根本。

　　2.predator n.食肉動物;掠奪者

　　Young birds are very vulnerable to predators.

　　幼小的鳥易受食肉動物傷害。

　　3.prey n.犧牲者;被掠食者

　　She was easy prey for dishonest salesmen.

　　她很容易地讓奸商敲了竹杠。

　　4.specialisation n.專門;專業化

　　Innovation and specialisation are more important.

　　創新和專業化更為重要。

　　5.preserve v.保護;保存;保持

　　It is highly important to preserve the environment.

　　保護自然環境至關重要。