摩洛哥出土的驚人化石改寫了演化時間線

原文網址：www.sciencedaily.com/releases/2015/07/150707213241.htm

Spectacular Moroccan fossils redefine evolutionary timelines

摩洛哥出土的驚人化石改寫了演化時間線

Some of the oldest marine animals on the planet, including armoured worm-like forms and giant, lobster like sea creatures, survived millions of years longer than previously thought, according to a spectacularly preserved fossil formation from southeastern Morocco.

位於摩洛哥東南，保存狀況驚人地良好的化石層顯示某些地球上最古老的海洋生物，包括一些覆有甲殼的蟲以及巨大、狀似龍蝦的海洋生物，存活的時間可能比之前所認為的還要長了數百萬年。

The Lower Fezouata formation has been revealing exciting discoveries about life in the Ordovician -- around 485 -- 444 million years ago -- since its discovery just five years ago.

自短短五年前發現下Fezouata層後，科學家便一直從中得到跟奧陶紀(Ordovician，4億8500年前至4億4400萬年前)生物有關的驚人發現。

'The Fezouata is extraordinarily significant' says Professor Derek Briggs of Yale University, co-author of a study published today in the Journal of the Geological Society. 'Animals typical of the Cambrian are still present in rocks 20 million years younger, which means there must be a cryptic record in between, which is not preserved.'

「Fezouata的重要性不言而喻，」耶魯大學的Derek Briggs教授說，他是本篇今日發表在《地質學會雜誌》(Journal of the Geological Society)上的論文的共同作者。「在寒武紀(Cambrian)過後2000萬年的岩石中仍能發現典型的寒武紀生物，代表說這之間一定有紀錄未被保存下來。」

Over 160 genera have already been documented from the Fezouata, with much more expected to be found. They include animals which would have looked perfectly at home during the Cambrian: armoured lobopodians -- worm like creatures with spines on their backs and short, stubby legs, and anomalocaridids -- huge segmented animals with remarkable feeding limbs, which are some of the largest marine creatures of the time.

從Fezouata出土的化石中，已經紀錄到超過160屬，未來預期還會發現更多。其中包括某些在寒武紀過得很自在的生物：有甲殼的葉足動物(lobopodian)，其背上有尖刺、足部粗短、看起來像蠕蟲；以及奇蝦(anomalocaridid)，為巨大的多節動物，擁有用來捕食的顯著前肢，其中有些種類為當時最大型的海洋生物之一。

As well as demonstrating the longevity of fauna thought to have been extinct millions of years previously, the Fezouata proves that other creatures evolved far earlier than previously thought.

Fezouata除了顯示過往認為已經消失數百萬年的動物可能更為長壽之外，也證實了某些生物較之前認為的還要早演化出來。

'Horseshoe crabs, for example, turn out to be at least 20 million years older than we thought. The formation demonstrates how important exceptionally preserved fossils are to our understanding of major evolutionary events in deep time' says Peter Van Roy, also of Yale, who first recognised the scientific importance of the Fezouata fauna and is lead author of the study, part of a project funded by the National Science Foundation.

「舉例來說，馬蹄蟹的出現時間至少比我們過去所認為的還要早了2000萬年。這個地層顯示了保存狀態格外良好的化石對我們瞭解過去的大型演化事件有多麼重要。」此篇研究的第一作者，同為耶魯大學的Peter Van Roy說，他是首先體認到Fezouata生物群在科學上的重要性的人。本研究部分由國家科學基金贊助。

The spectacular preservation, which includes detailed soft parts and organisms over 2 metres in length, is thanks to the fine grained, muddy sediments in which the organisms were preserved.

這些保存狀態良好的化石中包括某些細緻的軟組織以及超過2公尺長的生物，而這得歸功於保存這些生物的細粒泥質沉積物。

'These are special rocks' says Professor Briggs. 'Some of the organisms are enormous -- several metres in length. With such exceptional preservation, in a fully marine exposure, we can develop a reasonably full picture of what marine life looked like in the Ordovician.'

「這些岩石相當特殊，」Briggs教授說。「這些生物有些可以長到非常巨大，達數公尺這麼長。有了這些完整體現當時的海洋環境且保存相當良好的化石，我們可以合理描繪出在奧陶紀時的海洋生命的完整樣貌。」

The discoveries suggest the 'Great Ordovician Biodiversification Event' -- an explosion in diversity throughout the earlier part of the Ordovician period -- may have been a continuation of the Cambrian explosion.

這些發現顯示「奧陶紀生物大輻射」(Great Ordovician Biodiversification Event)--在奧陶紀早期時發生的生物多樣性大爆發事件—可能為寒武紀大爆發(Cambrian explosion)的接續事件。

'There is much more to learn from the Fezouata' says Professor Briggs. 'Why do we not see more assemblages like this in the Ordovician? What ecological changes happened at the Cambro-Ordovician interval? Are the Cambrian Explosion and the Great Ordovician Biodiversification Event separate, or phases of the same event?'

「我們還能從Fezouata中學到許多事物」Briggs教授說。「為什麼我們沒有在其他的奧陶系地層發現更多這種類型的生物組成？在寒武紀與奧陶紀交界時生態環境發生了什麼樣的變化？寒武紀大爆發與奧陶紀生物大輻射究竟是獨立的事件，亦或是同一事件的不同階段？」

The paper, published online today, marks the start of a themed series of 'Review focus' articles for the Journal of the Geological Society, centring on sites of exceptional fossil preservation spanning Earth's history. All papers in the series will be available for free download, and further 'Review focus' themes are planned.

此篇刊登在線上的論文，為《地質學會雜誌》上主題式「重點回顧」文章系列的開頭，此系列聚焦在地質歷史各時期中保有特別完整的化石的遺址。此系列的所有論文皆可以免費下載，而更多的主題式「重點回顧」文章系列正在規劃中。

'The purpose of these articles is to present a distilled, forward looking review of a topic', says the series editor Professor Philip Donoghue. 'We decided to start with a thematic series on fossil Lagerstätten since these deposits are fundamental archives of evolutionary history.'

「這些文章的目的在呈現對此主體的精簡未來展望。」本系列的編輯，Philip Donoghue教授說。「我們決定以關於化石庫(fossil Lagerstätten)的主題系列作為開端，這是因為這些沉積物為構築演化史的基石。」

'By making the papers freely available, it is hoped they will interest a wide range of readers, from undergraduates, to specialists in the field, to members of the public.'

「藉由讓這些文章可以被免費下載，我們希望它們能夠激起各個領域的讀者的興趣，從研究生至本領域的專家至普羅大眾。」

引用自：Geological Society of London. "Spectacular Moroccan fossils redefine evolutionary timelines." ScienceDaily. ScienceDaily, 7 July 2015. 

利用放射線定年更準確地得到地球最近一次磁極轉換的年代

原文網址：www.sciencedaily.com/releases/2015/07/150707101952.htm

An improved age for Earth's latest magnetic field reversal using radiometric dating

利用放射線定年更準確地得到地球最近一次磁極轉換的年代

Earth's magnetic field periodically reverses such that the north magnetic pole becomes the south magnetic pole. The latest reversal is called by geologists the Matuyama-Brunhes boundary (MBB), and occurred approximately 780,000 years ago. The MBB is extremely important for calibrating the ages of rocks and the timing of events that occurred in the geological past; however, the exact age of this event has been imprecise because of uncertainties in the dating methods that have been used.

地球的磁場會週期性的倒轉使得磁北極變成磁南極。地質學家稱呼最近一次的倒轉事件為松山-布容反轉界面(Matuyama-Brunhes boundary，MBB)，其發生在約78萬年前。MBB對於比對過去地質時間中的岩石與事件發生的年代都相當重要，然而受限於過去的定年方法的誤差，此事件的確切年代仍不太準確。

A team of researchers based in Japan and Canada have obtained an improved age for the MBB. The team studied volcanic ash that was deposited immediately before the MBB. This volcanic ash contains small crystals called zircons. Some of these crystals formed at the same time as the ash; thus, radiometric dating of these zircons using the uranium-lead method provided the exact age of the ash. To verify their findings, the researchers also used a different method to date sedimentary rock from the same place that was formed at the time of the MBB. The combined results demonstrate that the age of the MBB is 770.2 ± 7.3 thousand years ago. The research has been published in the journal Geology.

由加拿大與日本的科學家組成的研究團隊得到了更準確的MBB發生年代。此團隊的研究對象為剛好在MBB發生前沉積的火山灰。這層火山灰中含有稱為鋯石(zircon)的微小礦物結晶，其中有一些的形成時間與火山灰正好相同，因此火山灰的形成年代即為這些鋯石用鈾鉛定年(uranium-lead method)得出的年代。為了證實他們的發現，研究人員也利用其他的方法來定年沉積於同一個地方，時間為MBB發生時的沉積岩。這些結果組合起來顯示MBB的發生年代為770.2 ± 7.3千年前。此研究成果刊登於期刊《地質》(Geology)。

Dr. Yusuke Suganuma of the National Institute of Polar Research, Tokyo, who is the lead author on the paper, commented: "This study is the first direct comparison of radiometric dating, dating of sediments, and the geomagnetic reversal for the Matuyama-Brunhes boundary. Our work contributes calibrating the geological time scale, and will be extremely important in future studies of the events that occurred at this time."

本篇論文的第一作者，東京國立極地研究所(the National Institute of Polar Research, Tokyo)的菅沼悠介博士評論：「本研究為首篇對松山-布容反轉界面的放射性定年、沉積物定年與磁極反轉性質直接綜合比較的研究。我們的成果對地質年代表的校正助益良多，也對目標為發生在這段時期的地質事件的未來研究至關重要。」

引用自：Research Organization of Information and Systems. "An improved age for Earth's latest magnetic field reversal using radiometric dating." ScienceDaily. ScienceDaily, 7 July 2015. 

恐龍退下，魚類上場

原文網址：www.sciencedaily.com/releases/2015/06/150630100607.htm

Exit dinosaurs, enter fishes

Mass extinction event that killed the dinosaurs gave rise to modern 'age of fishes'

恐龍退下，魚類上場

毀滅恐龍的大滅絕事件造就了現今的魚類紀元

A pair of paleobiologists from Scripps Institution of Oceanography, UC San Diego have determined that the world's most numerous and diverse vertebrates ¬- ray-finned fishes -- began their ecological dominance of the oceans 66 million years ago, aided by the mass extinction event that killed off dinosaurs.

兩位來自加州大學聖地牙哥分校(UC San Diego)的斯克里普斯海洋學研究所(Scripps Institution of Oceanography)的古生物學家確認了世上數目最多且最多樣的脊椎動物—輻鰭魚(ray-finned fish)—於6600萬年前受惠於消滅恐龍的大滅絕事件而開始成為海洋生態系的主要角色。

Scripps graduate student Elizabeth Sibert and Professor Richard Norris analyzed the microscopic teeth of fishes found in sediment cores around the world and found that the abundance of ray-finned fish teeth began to explode in the aftermath of the mass die-off of species, which was triggered by an asteroid strike in the Yucatan Peninsula. Scientists refer to this episode as the Cretaceous-Paleogene (K/Pg) extinction event.

斯克里普斯的研究生Elizabeth Sibert與Richard Norris教授分析了世界各地的沉積物岩心中微小的魚類牙齒。他們發現輻鰭魚的牙齒數目在生物大滅絕後開始爆炸性的增長。此滅絕事件的成因為小行星撞擊猶加敦半島，科學家稱之為白堊紀-古第三紀(K/Pg)滅絕事件(Cretaceous-Paleogene (K/Pg) extinction event)。

Ninety-nine percent of all fish species in the world -- from goldfish to tuna and salmon -- are classified as ray-finned fishes. They are defined as species with bony skeletal structures and have teeth that are well preserved in deep ocean mud. Sharks, in contrast, have cartilaginous skeletons and are represented by both teeth and mineralized scales, also known as denticles, in marine sediments.

現今世上99%的魚類—從金魚至鮪魚及鮭魚—皆可歸類成輻鰭魚。牠們的定義為擁有硬骨質構造，而在深海底泥中可以發現牠們保存良好的牙齒。相反的，鯊魚則是擁有軟骨質構造，在海洋沉積物中可以發現牠們的牙齒與礦化的鱗片，稱作鱗突(denticle)。

"We find that the extinction event marked an ecological turning point for the pelagic marine vertebrates," write the authors in the study. "The K/Pg extinction appears to have been a major driver in the rise of ray-finned fishes and the reason that they are dominant in the open oceans today."

「我們發現這起滅絕事件標記了遠洋脊椎動物生態結構的轉捩點。」作者在此篇論文中寫道。「K/Pg滅絕事件顯然是輻鰭魚崛起的主要推手，以及牠們為何能主宰今日的開放海洋的原因。」

The breakthrough for the researchers in reaching their conclusion came through their focus on fossilized teeth and shark scales. In cores from numerous ocean basins, they found that while the numbers of sharks remained steady before and after the extinction event, the ratio of ray-finned fish teeth to shark teeth and scales gradually rose, first doubling then becoming eight times more abundant 24 million years after the extinction event. Now there are 30,000 ray-finned fish species in the ocean, making this class the most numerically diverse and ecologically dominant among all vertebrates on land or in the ocean.

研究人員之所以能夠得到此突破性的結論在於他們將焦點放在牙齒化石與鯊魚鱗片。從許多海盆鑽探出的岩心中，他們發現雖然在此次滅絕事件前後鯊魚的牙齒數目大致不變，輻鰭魚牙齒對鯊魚牙齒的數目比例卻逐漸上升。在滅絕事件後起初是兩倍，2400萬年後卻變成有八倍之多。現今的海洋中有多達30,000種的輻鰭魚，使得牠們成為陸地與海洋脊椎動物中多樣性最高，也最具有生態上的優勢的一類。

Scientists had known that the main diversification of ray-finned fishes had happened generally between 100 million and 50 million years ago.

科學家已經知道輻鰭魚的多樣化主要發生在1億至5000萬年前。

"The diversification of fish had never been tied to any particular event. What we found is that the mass extinction is actually where fish really took off in abundance and variety," said Sibert, who is the recipient of an NSF Graduate Research Fellowship. "What's neat about what we found is that when the asteroid hit, it completely flipped how the oceans worked. The extinction changed who the major players were."

「過往從未將魚類的多樣化跟任何特定事件牽上關連。而我們發現魚類實際上是從這次大滅絕事件後才開始變的多樣化且數目激增，」 Sibert說，其為美國國家科學基金會研究生獎學金的受獎者。「我們的研究精妙之處在於我們發現當小行星撞擊地球時，它同時也徹底顛覆了海洋的運作規則。這次的滅絕事件改變了誰才是擁有主導權的一方。」

Sibert and Norris believe that some key changes in the oceans might have helped ray-finned fishes along. Large marine reptiles disappeared during the mass extinction, as did the ammonites, an ancient cephalopod group similar to the chambered nautilus. Those species, the researchers believe, had been either predators of ray-finned fishes or competitors with them for resources.

Sibert與Norris認為發生在海洋的某些關鍵變化可能獨厚輻鰭魚。大型海洋爬蟲類在此次大滅絕中消失殆盡，同樣步上此命運的還有菊石，為一種類似鸚鵡螺的古代頭足鋼動物。研究人員認為這些動物在當時可能是輻鰭魚的天敵，或者會與牠們競爭資源。

"What's amazing," said Norris, "is how quickly fish double, then triple in relative abundance to sharks after the extinction, suggesting that fish were released from predation or competition by the extinction of other groups of marine life."

「迷人的是，」Norris說，「輻鰭魚的數量在此次大滅絕後迅速地增加為鯊魚的兩倍，然後是三倍之多，這顯示輻鰭魚從其他海洋生物的掠食或競爭壓力中解脫了。」

Sibert noted that before the extinction event, ray-finned fishes existed in a state of relative ecological insignificance, just like mammals on land.

Sibert發現在此次大滅絕事件之前，輻鰭魚在生態上的重要性相對而言並不高，就跟當時陸上的哺乳動物一樣。

"Mammals evolved 250 million years ago but didn't become really important until after the mass extinction. Ray-finned fishes have the same kind of story," said Sibert. "The lineage has been around for hundreds of millions of years, but without the mass extinction event 66 million years ago, it is very likely that the oceans wouldn't be dominated by the fish we see today."

「哺乳動物雖然在2500萬年前就已經演化出來，然而直到此次大滅絕發生之前牠們都不是那麼重要。而輻鰭魚的故事也有異曲同工之處。」Sibert說。「雖然牠們的血脈已流傳了數億年，但如果沒有那次發生在6600萬年前的大滅絕事件，海洋很有可能不會被我們今日所見的魚群主宰。」

引用自：University of California - San Diego. "Exit dinosaurs, enter fishes: Mass extinction event that killed the dinosaurs gave rise to modern 'age of fishes'." ScienceDaily. ScienceDaily, 30 June 2015.

新發現的環狀排列牙齒揭露了蛻皮動物的共祖樣貌

原文網址：www.sciencedaily.com/releases/2015/06/150624140239.htm

Newly found ring of teeth uncovers what common ancestor of molting animals looked like

新發現的環狀排列牙齒揭露了蛻皮動物的共祖樣貌

A new study of an otherworldly creature from half a billion years ago -- a worm-like animal with legs, spikes and a head difficult to distinguish from its tail -- has definitively identified its head for the first time, and revealed a previously unknown ring of teeth and a pair of simple eyes. The results, published today in the journal Nature, have helped scientists reconstruct what the common ancestor of everything from tiny roundworms to huge lobsters might have looked like.

一篇對一種生活在500萬年前，猶如來自異世界的生物—看起來像蟲，擁有許多腳與尖刺且首尾莫辨的動物—的新研究首次明確辨識出其頭部的樣貌，並且發現之前從未見過的環狀排列牙齒以及一對單眼。這篇刊登於本日《自然》(Nature)的新研究，重建了小至迴蟲，大至龍蝦的這些生物的共同祖先的可能模樣。

Researchers from the University of Cambridge, the Royal Ontario Museum and the University of Toronto have found that the creature, known as Hallucigenia due to its strange appearance, had a throat lined with needle-like teeth, a previously unidentified feature which could help connect the dots between it, modern velvet worms and arthropods -- the group which contains modern insects, spiders and crustaceans.

來自劍橋大學(the University of Cambridge)、皇家安大略博物館(the Royal Ontario Museum)與多倫多大學(the University of Toronto)的研究人員，發現這種稱為「怪誕蟲」(Hallucigenia，命名顯然來自於牠奇怪的外表)的生物，擁有佈滿針狀牙齒的喉嚨。這種之前未發現的特徵幫助研究人員建立起活在現代的天鵝絨蟲(velvet worm)及節肢動物(arthropod，包括現代的昆蟲、蜘蛛與甲殼類)跟這種古代生物之間的關聯。

Arthropods, velvet worms (onychophorans) and water bears (tardigrades) all belong to the massive group of animals that moult, known as ecdysozoans. Though Hallucigenia is not the common ancestor of all ecdysozoans, it is a precursor to velvet worms. Finding this mouth arrangement in Hallucigeniahelped scientists determine that velvet worms originally had the same configuration -- but it was eventually lost through evolution.

節肢動物、天鵝絨蟲(為有爪動物(onychophoran))及水熊(water bear，為緩步動物(tardigrade))皆屬於蛻皮動物(ecdysozoan)大家族的一分子，這類動物的特徵便是會蛻皮。雖然怪誕蟲並非所有蛻皮動物的共同祖先，但其為天鵝絨蟲的前驅。發現怪誕蟲的口腔形態讓科學家確認原本天鵝絨蟲的口腔也有這些特徵，但經過漫長的演化後最終失去了這些特徵。

"The early evolutionary history of this huge group is pretty much uncharted," said Dr Martin Smith, a postdoctoral researcher in Cambridge's Department of Earth Sciences, and the paper's lead author. "While we know that the animals in this group are united by the fact that they moult, we haven't been able to find many physical characteristics that unite them."

「這一大類動物的早期演化歷史大半仍隱藏在迷霧當中，」Martin Smith博士說，他是劍橋大學地質科學系的博士後研究員，也是本篇論文的第一作者。「即使我們知道這群動物的共同特徵是牠們都會蛻皮，我們卻未能發現更多的共同生理特徵。」

"It turns out that the ancestors of moulting animals were much more anatomically advanced than we ever could have imagined: ring-like, plate-bearing worms with an armoured throat and a mouth surrounded by spines," said Dr Jean-Bernard Caron, Curator of Invertebrate Palaeontology at the Royal Ontario Museum and Associate Professor in the Departments of Earth Sciences and Ecology & Evolutionary Biology at the University of Toronto. "We previously thought that neither velvet worms nor their ancestors had teeth. But Hallucigenia tells us that actually, velvet worm ancestors had them, and living forms just lost their teeth over time."

「顯然蛻皮動物的祖先的構造較我們之前認為的更加先進：牠們的環狀蟲體上覆有硬板，並擁有批甲的喉部及被尖刺環繞的嘴部。」Jean-Bernard Caron博士說，他是皇家安大略博物館無脊椎古生物部門的研究人員，同時也是多倫多大學地球科學暨生態與演化生物學系的副教授。「我們之前認為天鵝絨蟲與牠們的祖先都沒有牙齒。但怪誕蟲告訴我們天鵝絨蟲的祖先實際上是有牙齒的，而現生種不過是在演化過程中失去了它們。」

Hallucigenia was just one of the weird creatures that lived during the Cambrian Explosion, a period of rapid evolutionary development starting about half a billion years ago, when most major animal groups first emerge in the fossil record.

怪誕蟲不過是生活在寒武紀大爆發(the Cambrian Explosion)時的眾多奇特生物的其中之一，此時期發生於約5000萬年前，當時動物的演化程度大幅躍進，大多數主要的動物類別首次出現於這段時間的化石紀錄中。

At first, Hallucigenia threw palaeontologists for a bit of a loop. When it was identified in the 1970s, it was reconstructed both backwards and upside down: the spines along its back were originally thought to be legs, its legs were thought to be tentacles along its back, and its head was mistaken for its tail.

起初，怪誕蟲讓科學家有些困惑。發現於1970年代，科學家在重建牠的樣貌時卻將上下前後都顛倒了：長在背部的成排釘刺原先被認為是腳，腿被認為是長在背上的觸鬚，頭部則被誤認成尾端。

Right side up and right way round, Hallucigenia still looks pretty strange: it had pairs of lengthy spines along its back, seven pairs of legs ending in claws, and three pairs of tentacles along its neck. The animals were between 10 and 50 millimetres in length and lived on the floor of the Cambrian oceans.

即使將上下前後導正過來，怪誕蟲看起來還是相當奇異：背上有兩排長長的尖刺，七對末端帶爪的足部，頸部長有三對觸鬚。這種生物長約10至50釐米，生活在寒武紀的海床上。

More significantly, Hallucigenia's unearthly appearance has made it difficult to link it to modern animal groups and to find its home in the Tree of Life. In 2014, research from Cambridge partially solved this problem by studying the structure of Hallucigenia's claws, which helped definitively link it to modern velvet worms.

更重要的是，怪誕蟲怪異的外表讓人很難將牠跟其他的現生生物連在一起，因此難以確認牠在演化樹中的定位。在2014年，劍橋大學的科學家解決了這個難題的一部分。藉由研究怪誕蟲的爪子構造，他們認為牠與現代的天鵝絨蟲絕對有所關連。

In the new work, researchers used electron microscopy to examine fossils from the collections of the Royal Ontario Museum and the Smithsonian Institution, definitively sorting Hallucigenia's front from back, and making some surprising observations.

在本篇新研究中，研究人員利用電子顯微鏡檢視皇家安大略博物館與史密森尼學會(the Smithsonian Institution)蒐集的怪誕蟲標本，而確認了牠們的首尾方向，並且得到一些驚人的發現。

"Prior to our study there was still some uncertainty as to which end of the animal represented the head, and which the tail," said Smith. "A large balloon-like orb at one end of the specimen was originally thought to be the head, but we can now demonstrate that this actually wasn't part of the body at all, but a dark stain representing decay fluids or gut contents that oozed out as the animal was flattened during burial."

「在我們的研究之前，大家仍不太確定這種動物哪一端是頭，哪一端是尾巴，」Smith說。「位於其中一端的氣球外型球體原先被認為是頭部，但現在我們認為那根本就不是身體的任何一部份，而是液體分解後留下的暗色汙漬，或是蟲體被埋藏而壓扁時，從腸道擠出來的內容物。」

Identifying this end as the tail led Caron to revisit the fossils and dig away the sediment that was covering the head: the animals died as they were buried in a mudslide, and their floppy head often ended up pointing down into the mud. "This let us get the new images of the head," said Caron. "When we put the fossils in the electron microscope, we were initially hoping that we might find eyes, and were astonished when we also found the teeth smiling back at us!"

確認哪邊是尾部後，Caron重新檢視那些化石，並挖除覆蓋頭部的沉積物。由於這些動物被一場泥流活埋而死亡，造成牠們柔軟的頭部常常會朝下埋在泥中。「這讓我們可以看到全新的頭部影像。當我們將牠擺在電子顯微鏡下，本來我們希望可以看到牠的眼睛，而讓人驚喜的是牠竟然還對我們露齒微笑！」

The new images show an elongated head with a pair of simple eyes, which sat above a mouth with a ring of teeth. In addition, Hallucigenia's throat was lined with needle-shaped teeth. The fossils originated in the Burgess Shale of Yoho National Park in western Canada, one of the world's richest sources of fossils from the Cambrian period.

這些新的影像顯示牠們的長型頭部帶有一對單眼，位在有環狀排列牙齒的口部上方。此外，怪誕蟲的喉部有許多細小的針狀牙齒排列其中。這些化石出土於加拿大西部幽鶴國家公園(Yoho National Park)的伯吉斯頁岩(the Burgess Shale)，為世上最豐富的寒武紀化石寶庫之一。

The ring of teeth that surrounded Hallucigenia's mouth probably helped to generate suction, flexing in and out, like a valve or a plunger, in order to suck its food into its throat. The researchers speculate that the teeth in the throat worked like a ratchet, keeping food from slipping out of the mouth each time it took another 'suck' at its food.

環繞在怪誕蟲口部週遭的牙齒也許能夠幫助產生吸力。怪誕蟲將牙齒伸進伸出，達到類似活塞或活瓣的功能，以將食物吸入至牠的喉部。研究人員猜測牠喉部的牙齒可以鉤住食物，防止在另一次吸入食物時之前的食物溜出牠的嘴巴。

"These teeth resemble those we see in many early moulting animals, suggesting that a tooth-lined throat was present in a common ancestor," said Caron. "So where previously there was little reason to think that arthropod mouths had much in common with the mouths of animals such as penis worms, Hallucigenia tells us that arthropods and velvet worms did ancestrally have round-the-mouth plates and down-the-throat teeth -- they just lost or simplified them later."

「這些牙齒與許多早期的蛻皮動物十分相似，顯示牠們的共同祖先擁有佈滿牙齒的喉嚨。」Caron說。「先前幾乎沒有理由認為節肢動物與陰莖蟲(penis worm)這類生物的口部會有許多共同之處，但怪誕蟲告訴我們節肢動物與天鵝絨蟲都有環繞在口部的硬板，與深至喉嚨的的牙齒，只是之後這些特徵在後者身上失去或者退化了。」

The material for this study was collected between 1992 and 2000 and represents more than 165 additional Hallucigenia specimens -- including many rare orientations and well-preserved specimens.

此研究的對象包含了從1992年至2000年所收集的超過165個怪誕蟲樣品，包含許多呈現少見方位與保存良好的樣品。

Parks Canada, which holds jurisdiction over the Burgess Shale sites located in Yoho and Kootenay national parks, is thrilled by this discovery and eager to share this exciting new piece of the ever-unfolding Burgess Shale story with their visitors.

擁有管裡幽鶴國家公園與庫特尼國家公園(Kootenay National Park)境內的伯吉斯頁岩的加拿大公園管理局(Parks Canada)，對這些發現十分興奮並積極將這些未曾公開的伯吉斯頁岩的故事與他們的遊客分享。

The research was funded by Clare College, Cambridge, the Natural Sciences and Engineering Research Council of Canada, and the Royal Ontario Museum.

此研究由劍橋大學克萊爾學院(Clare College, Cambridge)、加拿大自然科學及工程研究委員會(the Natural Sciences and Engineering Research Council of Canada)及皇家安大略博物館(the Royal Ontario Museum)資助。

Video: https://www.youtube.com/watch?v=p5LMG0fEBb8

引用自：University of Cambridge. "Newly found ring of teeth uncovers what common ancestor of molting animals looked like." ScienceDaily. ScienceDaily, 24 June 2015. 

利用地面原子鐘監測火山

原文網址：www.sciencedaily.com/releases/2015/06/150630080156.html

Monitoring volcanoes with ground-based atomic clocks

利用地面原子鐘監測火山

An international team led by scientists from the University of Zurich finds that high-precision atomic clocks can be used to monitor volcanoes and potentially improve predictions of future eruptions. In addition, a ground-based network of atomic clocks could monitor the reaction of Earth's crust to solid Earth tides.

由蘇黎世大學(the University of Zurich)的科學家所率領的國際團隊發現高精度的原子鐘(atomic clock)可以用來監測火山，並有潛力對未來的爆發做出更精準的預測。此外，原子鐘的地面觀測網還能夠監測地殼對固體地潮的反應。

Atomic clocks measure time with unbelievable accuracy. The best atomic clocks are so precise that they would lose less than one second over a period of 10 billion years. However, they are generally only used in laboratories. Science and industry have yet to take full advantage of their unprecedented ability to measure time. An international team including Dr. Ruxandra Bondarescu, Andreas Schärer and Prof. Philippe Jetzer from the Institute of Physics from the University of Zurich discusses potential applications for atomic clocks.
原子鐘能夠以不可思議的準確度測量時間。最好的原子鐘可以精準至100億年內誤差不到一秒。然而，一般只有在實驗室內才會用到它們。科學界與產業界尚未能夠完全發揮它們前所未見的高精準計時能力。包括蘇黎世大學物理研究所的Ruxandra Bondarescu與Andreas Schärer博士及Philippe Jetzer教授的國際研究團隊對原子鐘的潛在應用面提出討論。
Their analysis shows that the slow down of time predicted by general relativity can be measured by local clocks and used to monitor volcanoes. General relativity states that clocks positioned at different distances from a massive body like Earth have different tick rates. The closer a clock is to a massive object, the slower it ticks. In a similar manner, subterranean objects influence the tick rate of local clocks that are located above Earth's surface. New lava filling a magma chamber beneath a volcano makes a clock located above that volcano tick more slowly than a clock that is located further away. Volcanoes are currently monitored using GPS receivers. The resulting data often has to be integrated over a period of several years before an estimate of the volume of new magma can be made. A network of local, highly precise atomic clocks may provide the same information within a few hours. This would make it possible to monitor processes inside volcanoes more closely and to make better predictions for future volcanic eruptions.
他們的分析顯示地面原子鐘可以測量到廣義相對論所預測的時間減速，並能夠用來監測火山活動。在廣義相對論的敘述中，當兩座時鐘跟地球這種大質量物體的距離不一樣時，它們的行走速率也會不一樣。時鐘離大質量物體越近，行走速率就會越慢。類似地，在地下的物體也會影響位於上方地表的時鐘的行走速率。當新的熔岩進入火山下方的岩漿庫時，它會造成位於火山上方的時鐘的運行速率變得比遠方的時鐘還要慢。現今我們利用GPS接收器來監測火山，這通常需要先累積數年的觀測資料才能開始預估新的岩漿體積有多少。然而，架設在當地，精準度極高的地面原子鐘觀測網卻可能可以在數個小時內提供給我們相同的資訊。這讓我們可以更詳細的觀測火山內部的活動，並且對未來的火山噴發做出更精準的預測。
Monitoring the solid Earth tides with a global network of atomic clocks
利用全球原子鐘觀測網來監測固體地潮
Atomic clocks can also be used to monitor the solid Earth tides. Tides occur because Earth moves in the gravitational field of the Sun and the Moon. It reacts to this outer field by deforming, which in turn leads to ocean tides and to the ground on the continents lifting and falling regularly. The ground can rise as much as 50 cm. A global network of atomic clocks that are connected via fiber optic cables used for internet, could provide continuous measurements of Earth tides and check existing theoretical models. It would also be possible to examine any local differences in the response of Earth's crust to Earth tides.
原子鐘也能夠用來監測固體地潮(solid Earth tide)。潮汐的發生原因是因為地球在太陽與月球的重力場之間運行。這些外在的重力場會讓地球變形，造成海洋發生潮汐，而地面也會規律的漲落，幅度可達到50 cm。利用串聯網路的光纖來建立全球原子鐘觀測網，可以持續地測量地潮並用來驗證現行的理論模型是否符合觀測結果，並且能夠用來觀察地殼對地潮的反應是否有區域性差異存在。
The researchers hope that high precision clocks could be deployed in volcanic areas in the next few years. This is, however, subject to sufficient interest and investment from industry. "We need this additional tool to monitor magma movement under volcanoes such as the Yellowstone supervolcano, which is overdue for an explosion that would alter life on Earth as we known it," explains Bondarescu.
研究人員冀望在未來的幾年內這種高精確度的時鐘便能夠實際運用在火山地區。然而，這有賴於產業界是否有充分的興趣而決定投資。「我們需要額外的工具來監測像是黃石公園這類超級火山之下的岩漿活動，據我們所知它們的噴發足以改變地球上的全體生物，且這早就應該要發生了。」Bondarescu解釋。

引用自University of Zurich. "Monitoring volcanoes with ground-based atomic clocks." ScienceDaily. ScienceDaily, 30 June 2015.