早在海洋生物出现之前很久，陆地动物就开始在地球上最大的灭绝中死亡

Around a quarter of a billion years ago, the vast majority of species on land and sea were wiped out in The Great Dying, thanks to a series of volcanic eruptions spewing out noxious greenhouse gases.

大约25亿年前，由于一系列喷出有害温室气体的火山爆发，陆地和海洋上的绝大多数物种在大灭绝中灭绝。

With the discovery that land animals had a big head start in this tremendous mass extinction, researchers are now starting to suspect there might have been a lot more to the story, making the end of the Permian a truly unfortunate time to be alive.

随着发现陆生动物在这次大规模灭绝中占了很大的先机，研究人员现在开始怀疑可能还有更多的故事，使得二叠纪的结束成为一个真正不幸的生存时间。

An international team of geologists and palaeobiologists has uncovered evidence that could reset the established timeline on when life around the planet started to die out during the Permian extinction.

一个由地质学家和古生物学家组成的国际团队发现了一些证据，这些证据可能会重新设定地球上的生命在二叠纪大灭绝期间开始灭绝的既定时间。

A little over 250 million years ago, when dinosaurs were barely in the early prototype phase, Earth was going through a bit of a rough patch. There are signs that tectonic activity near what is now Siberia generated pulses of eruptions that coincided with the loss of about 90 percent of all species.

大约2亿5千万年前，当恐龙还处于早期原型阶段时，地球正经历着一段艰难的时期。有迹象表明，在现在的西伯利亚附近的构造活动产生了火山喷发的脉冲，与此同时，大约90%的物种消失了。

Evidence of the volcanic tantrums can be found in changes in the chemistry of the geological record, while hints of the mass extinction are seen in the rapid dwindling of relatively common plant fossils and animals, such as Daptocephalus, and the increase of bones of opportunist species, such as the pig-like Lystrosaurus.

火山爆发的证据可以从地质记录中的化学变化中找到，而大规模灭绝的迹象则可以从相对常见的植物化石和动物(如剑尾鱼)的迅速减少和机会主义物种(如猪状溶血龙)骨骼的增加中看到。

Previous research suggests there was no sign that something bad was about to happen, either. It was relatively clear sailing, and then - in the geological blink of an eye - all hell broke loose.

之前的研究表明，也没有迹象表明会发生什么不好的事情。这是相对清晰的航行，然后——在地质上一眨眼的功夫——一切都乱了套。

"Most people thought that the terrestrial collapse started at the same time as the marine collapse, and that it happened at the same time in the Southern Hemisphere and in the Northern Hemisphere," says palaeobotanist Cindy Looy from the University of California, Berkeley.

来自加州大学伯克利分校的古植物学家辛迪·鲁伊说：“大多数人认为，陆地塌陷与海洋塌陷同时开始，南半球和北半球也同时发生。”。

The standard for separating the tail end of the Permian from the start of the Triassic is based on a marine fossil bed near the city of Meishan in southern China. Its sediments point to a catastrophic moment 251.96 million years ago (give or take 35,000 years or so) when aquatic ecosystems collapsed and around 96 percent of all ocean species died out.

从三叠纪开始到二叠纪末的划分标准，是基于中国南方梅山市附近的一个海洋化石层。它的沉积物指出了25196万年前的一个灾难性时刻(大约35000年左右)，当时水生生态系统崩溃，约96%的海洋物种灭绝。

But it's not the only authority on the Permian-Triassic line.

但它并不是二叠纪-三叠纪界线上唯一的权威。

Looy led the team in an analysis of isotopes found in crystals of zircon embedded in a pristine sample of volcanic ash from what's known as the Karoo Basin in South Africa.

鲁伊带领研究小组，对埋在南非卡鲁盆地原始火山灰样本中的锆石晶体中发现的同位素进行了分析。

"The Karoo Basin is the poster child for the end-Permian vertebrate turnover, but until recently, it was not well-dated," says Looy.

鲁伊说：“卡鲁盆地是二叠纪末脊椎动物更替的典型代表，而直到最近，它仍旧保持着独特性。”。

Back during the Permian, the basin was part of the Gondwana landmass. It's in these Southern Hemisphere fossil records that signs of vanishing terrestrial life are clearest.

早在二叠纪，盆地是冈瓦纳大陆的一部分。正是在这些南半球的化石记录中，陆地生物消失的迹象最为明显。

Sure enough, the team failed to find pollen from significant species of land plants in the sediment immediately above the ash, confirming life on land was already beginning to fade soon after it was deposited.

果然，研究小组未能在火山灰正上方的沉积物中发现来自重要陆地植物物种的花粉，证实了陆地上的生命在沉积后不久就开始衰退。

But there was something odd about the isotope signature of the zircon itself. It suggested the volcanic material had been lying there for 252.24 million years.

但是锆石本身的同位素特征有些奇怪。它表明，这些火山物质在那里已经存在了2.524亿年。

Even taking some wiggle room into account, it seemed the ash was dropped hundreds of thousands of years before the sediment that defines the boundary near Meishan.

即使考虑到一些回旋的余地，似乎在界定眉山附近边界的沉积物形成之前，火山灰就已经落下了数十万年。

Either there was a mistake, or the Permian extinction event was much slower, with land species slipping away in the south first, followed a few hundred thousand years later by sea life throughout the north.

要么是弄错了，要么是二叠纪大灭绝的过程要慢得多，南方的陆生物种首先消失，而北方的海洋生物则在几十万年后才出现。

A similar study based on Australian geology was published earlier this year by a different team of researchers, also pointing to an earlier start to extinction on land. Thus, it's looking increasingly like The Great Dying was more staggered than we thought.

另一组研究人员今年早些时候发表了一项基于澳大利亚地质学的类似研究，也指出了陆地物种灭绝的开始时间更早。因此，看起来越来越像伟大的死亡比我们想象的更令人震惊。

This research was published in Nature Communications.

这项研究发表在《自然通讯》杂志上。