考古新发现：人类的祖先是老鼠

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.

考古发现，上图这种长相和老鼠类似的啮齿动物是人类的祖先，虽然这位祖先的外貌不是很出众。近日，朴茨茅斯大学的古生物学者们在多赛特郡的侏罗纪海岸发现了这种生活在1.45亿年前的小型夜行哺乳动物的残骸。

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.

这种远古动物最终会进化为人类，而且在演变过程中，还会进化成蓝鲸和鼩鼱等多种不同生物。

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.

新发现的这个物种被命名为Durlstotherim newmani，得名于热心的业余古生物学家查理•纽曼的名字。51岁的纽曼是沃斯麦特勒佛的Square and Compass酒馆的老板，他在酒馆里创办了自己的化石博物馆，帮助科学家收集到了这些新样本。

Mr Newman, made headlines in 2017 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.

纽曼曾在2017年用自己农场里的35吨木材建造了一个12英尺高的“巨石阵”，并因此登上了资讯头条，不过后来波倍克区议会命他将其拆除。

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.

今年早些时候，朴茨茅斯大学的本科生格兰特•史密斯发现了一把牙齿化石，该校的研究员史蒂夫•斯威特曼博士根据这些化石识别出了这一新物种。

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.

斯威特曼博士说：“格兰特当时正在筛选从多赛特海岸上收集到的最早的白垩纪小块岩石样本，希望能找到一些有趣的遗骸用于他的本科论文项目。”

“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，他找到了不止一块，而是两块非常特别的牙齿，这种牙齿类型从未在这个年代的岩石中见过。他请我过去看一下，想听听我的意见，结果我才看了一眼就惊呆了。”

“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.

“这种牙齿的进化程度很高，我马上就意识到这可能是白垩纪早期哺乳动物的遗骸，白垩纪早期哺乳动物和6000万年后的白垩纪末期哺乳动物更相似。”

“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.”

“这个标本得名于一个酒馆老板，因为他是个热心的业余古生物学家，在他的酒馆有个小型博物馆。他帮我们收集样本，在其他方面也非常乐于助人、热情好客。”

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.

斯威特曼博士认为这种哺乳动物是一种毛绒绒的小动物，极有可能在夜间活动。第二个标本也已经确认并以科学家保罗•恩索姆的名字命名。这些动物很可能居住在地洞中，以昆虫或植物为食。

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

斯威特曼博士补充说：“这些牙齿是高度进化的，可以刺穿、咬断和碾碎食物。”

“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.”

“这些牙齿磨损很严重，这意味着牙齿主人在它的种群中很长寿。要知道，和食肉恐龙共存绝非易事。”

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

这些牙齿是在斯沃尼奇附近的悬崖上的岩石中找到的。在斯沃尼奇一带曾发现数千块重要化石。

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.

朴茨茅斯大学的古生物学教授戴维•马提尔最开始是从史密斯那里看到这些牙齿的，他确定这些牙齿是哺乳动物的，但是对于这些牙齿为什么会出现在古老的岩层中很迷惑。

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.

随着时间的流逝，哺乳动物的牙齿从非常简单的效率不高的牙齿进化成可以轻易地撕裂、咀嚼和碾碎食物的接近臼齿的脊状牙齿。像Durlstotherim newmani一样高度进化的牙齿，先前只在8600万到6600万年前的白垩纪晚期的岩层中找到过。

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.

马提尔博士说：“我们用显微镜观察了这些牙齿，尽管拥有三十多年的从业经验，这些牙齿在我看来仍然非常异样。但史蒂夫马上就想到了。”

“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.”

“侏罗纪海岸总是不断地揭开新的秘密，我期待类似的发现会继续在我们眼前涌现。”

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

斯威特曼博士说，这一发现改写了哺乳动物的进化史。

“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.

他说：“在古生物学领域中，学者们对于在中国发现的一个大约有1.6亿年历史的标本有很多争论。”

“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.”

“最初人们认为该标本和我们发现的标本是同一种，但是最近的研究排除了这种可能性。既然如此，我们所发现的1.45亿年历史的牙齿主人无疑是已知最早的人类的哺乳动物祖先。”