考古新發(fā)現(xiàn)：人類的祖先是老鼠

As ancestors go, it might not look particularly distinguished, but this toothy rat-like creature is the forefather of us all. Remains of the little nocturnal mammal, which lived 145 million years ago, were recently discovered on the Jurassic Coast of Dorset, by paleontologists from the University of Portsmouth.

考古發(fā)現(xiàn)，上圖這種長(zhǎng)相和老鼠類似的嚙齒動(dòng)物是人類的祖先，雖然這位祖先的外貌不是很出眾。近日，樸茨茅斯大學(xué)的古生物學(xué)者們?cè)诙噘愄乜さ馁_紀(jì)海岸發(fā)現(xiàn)了這種生活在1.45億年前的小型夜行哺乳動(dòng)物的殘骸。

The animal is the earliest in a line that would eventually lead to humans, as well as branching off along the way to evolve into creatures as diverse as Blue Whales and Pigmy Shrews.

這種遠(yuǎn)古動(dòng)物最終會(huì)進(jìn)化為人類，而且在演變過程中，還會(huì)進(jìn)化成藍(lán)鯨和鼩鼱等多種不同生物。

The new species has been named ‘Durlstotherim newmani’, after keen amateur paleontologist Charlie Newman, 51, the landlord of the Square and Compass in Worth Matravers who founded his own fossil museum in the pub, and helped scientists collect the new specimens.

新發(fā)現(xiàn)的這個(gè)物種被命名為Durlstotherim newmani，得名于熱心的業(yè)余古生物學(xué)家查理•紐曼的名字。51歲的紐曼是沃斯麥特勒佛的Square and Compass酒館的老板，他在酒館里創(chuàng)辦了自己的化石博物館，幫助科學(xué)家收集到了這些新樣本。

Mr Newman, made headlines in 2015 when he built his own 12ft high ‘Stonehenge’ using 35 tonnes of timber in a field he owns in the village, although he was later ordered to tear it down by Purbeck District Council.

紐曼曾在2015年用自己農(nóng)場(chǎng)里的35噸木材建造了一個(gè)12英尺高的“巨石陣”，并因此登上了新聞?lì)^條，不過后來波倍克區(qū)議會(huì)命他將其拆除。

The new species were identified from just a handful of fossilised teeth which were found by Portsmouth University undergraduate Grant Smith earlier this year, and identified by Dr Steve Sweetman, a research fellow at the university.

今年早些時(shí)候，樸茨茅斯大學(xué)的本科生格蘭特•史密斯發(fā)現(xiàn)了一把牙齒化石，該校的研究員史蒂夫•斯威特曼博士根據(jù)這些化石識(shí)別出了這一新物種。

Dr Sweetman said: “Grant was sifting through small samples of earliest Cretaceous rocks collected on the coast of Dorset as part of his undergraduate dissertation project in the hope of finding some interesting remains.

斯威特曼博士說：“格蘭特當(dāng)時(shí)正在篩選從多賽特海岸上收集到的最早的白堊紀(jì)小塊巖石樣本，希望能找到一些有趣的遺骸用于他的本科論文項(xiàng)目。”

“Quite unexpectedly he found not one but two quite remarkable teeth of a type never before seen from rocks of this age. I was asked to look at them and give an opinion and even at first glance my jaw dropped.

“出乎意料的是，他找到了不止一塊，而是兩塊非常特別的牙齒，這種牙齒類型從未在這個(gè)年代的巖石中見過。他請(qǐng)我過去看一下，想聽聽我的意見，結(jié)果我才看了一眼就驚呆了。”

“The teeth are of a type so highly evolved that I realised straight away I was looking at remains of Early Cretaceous mammals that more closely resembled those that lived during the latest Cretaceous - some 60 million years later in geological history.

“這種牙齒的進(jìn)化程度很高，我馬上就意識(shí)到這可能是白堊紀(jì)早期哺乳動(dòng)物的遺骸，白堊紀(jì)早期哺乳動(dòng)物和6000萬(wàn)年后的白堊紀(jì)末期哺乳動(dòng)物更相似。”

“The specimen is named after a pub landlord because he is a keen amateur paleontologist and has a small museum in his pub. He helped us collect samples and was otherwise very helpful and hospitable.”

“這個(gè)標(biāo)本得名于一個(gè)酒館老板，因?yàn)樗莻€(gè)熱心的業(yè)余古生物學(xué)家，在他的酒館有個(gè)小型博物館。他幫我們收集樣本，在其他方面也非常樂于助人、熱情好客。”

Dr Sweetman believes the mammal was a small, furry creature and most likely nocturnal. A second species was also identified and named after scientist, Paul Ensom. The creatures probably lived in burrows feeding on insects, or plants.

斯威特曼博士認(rèn)為這種哺乳動(dòng)物是一種毛絨絨的小動(dòng)物，極有可能在夜間活動(dòng)。第二個(gè)標(biāo)本也已經(jīng)確認(rèn)并以科學(xué)家保羅•恩索姆的名字命名。這些動(dòng)物很可能居住在地洞中，以昆蟲或植物為食。

“The teeth are of a highly advanced type that can pierce, cut and crush food,” added Dr Sweetman.

斯威特曼博士補(bǔ)充說：“這些牙齒是高度進(jìn)化的，可以刺穿、咬斷和碾碎食物。”

“They are also very worn which suggests the animals to which they belonged lived to a good age for their species. No mean feat when you’re sharing your habitat with predatory dinosaurs.”

“這些牙齒磨損很嚴(yán)重，這意味著牙齒主人在它的種群中很長(zhǎng)壽。要知道，和食肉恐龍共存絕非易事。”

The teeth were recovered from rocks exposed in cliffs near Swanage which has given up thousands of iconic fossils.

這些牙齒是在斯沃尼奇附近的懸崖上的巖石中找到的。在斯沃尼奇一帶曾發(fā)現(xiàn)數(shù)千塊重要化石。

Dave Martill, Professor of Palaeobiology, at Portsmouth was originally shown the teeth by Mr Smith, and confirmed they were mammalian, but was puzzled as to what they were doing in such an old layer of rock.

樸茨茅斯大學(xué)的古生物學(xué)教授戴維•馬提爾最開始是從史密斯那里看到這些牙齒的，他確定這些牙齒是哺乳動(dòng)物的，但是對(duì)于這些牙齒為什么會(huì)出現(xiàn)在古老的巖層中很迷惑。

Mammal teeth evolved over time, from very simple ones that were not very efficient, to molar-like ridged teeth which could tear, chew and grind food very easily. Teeth as well-evolved as Durlstotherim newmani, have previously only been found in rock layers from, the late Cretaceous, between 86 and 66 million years ago.

隨著時(shí)間的流逝，哺乳動(dòng)物的牙齒從非常簡(jiǎn)單的效率不高的牙齒進(jìn)化成可以輕易地撕裂、咀嚼和碾碎食物的接近臼齒的脊?fàn)钛例X。像Durlstotherim newmani一樣高度進(jìn)化的牙齒，先前只在8600萬(wàn)到6600萬(wàn)年前的白堊紀(jì)晚期的巖層中找到過。

Professor Martill said: “We looked at them with a microscope but despite over 30 years’ experience these teeth looked very different. Steve made the connection immediately.

馬提爾博士說：“我們用顯微鏡觀察了這些牙齒，盡管擁有三十多年的從業(yè)經(jīng)驗(yàn)，這些牙齒在我看來仍然非常異樣。但史蒂夫馬上就想到了。”

“The Jurassic Coast is always unveiling fresh secrets and I’d like to think that similar discoveries will continue to be made right on our doorstep.”

“侏羅紀(jì)海岸總是不斷地揭開新的秘密，我期待類似的發(fā)現(xiàn)會(huì)繼續(xù)在我們眼前涌現(xiàn)。”

Dr Sweetman said the finds rewrite the history of mammal evolution.

斯威特曼博士說，這一發(fā)現(xiàn)改寫了哺乳動(dòng)物的進(jìn)化史。

“In the world of palaeontology there has been a lot of debate around a specimen found in China, which is approximately 160 million years old,” he added.

他說：“在古生物學(xué)領(lǐng)域中，學(xué)者們對(duì)于在中國(guó)發(fā)現(xiàn)的一個(gè)大約有1.6億年歷史的標(biāo)本有很多爭(zhēng)論。”

“This was originally said to be of the same type as ours but recent studies have ruled this out. That being the case, our 145 million year old teeth are undoubtedly the earliest yet known from the line of mammals that lead to our own species.”

“最初人們認(rèn)為該標(biāo)本和我們發(fā)現(xiàn)的標(biāo)本是同一種，但是最近的研究排除了這種可能性。既然如此，我們所發(fā)現(xiàn)的1.45億年歷史的牙齒主人無(wú)疑是已知最早的人類的哺乳動(dòng)物祖先。”