早在海洋生物出現(xiàn)之前很久，陸地動物就開始在地球上最大的滅絕中死亡

早在海洋生物出現(xiàn)之前很久，陸地動物就開始在地球上最大的滅絕中死亡

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.

大約25億年前，由于一系列噴出有害溫室氣體的火山爆發(fā)，陸地和海洋上的絕大多數(shù)物種在大滅絕中滅絕。

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.

隨著發(fā)現(xiàn)陸生動物在這次大規(guī)模滅絕中占了很大的先機(jī)，研究人員現(xiàn)在開始懷疑可能還有更多的故事，使得二疊紀(jì)的結(jié)束成為一個真正不幸的生存時間。

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.

一個由地質(zhì)學(xué)家和古生物學(xué)家組成的國際團(tuán)隊發(fā)現(xiàn)了一些證據(jù)，這些證據(jù)可能會重新設(shè)定地球上的生命在二疊紀(jì)大滅絕期間開始滅絕的既定時間。

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.

大約2億5千萬年前，當(dāng)恐龍還處于早期原型階段時，地球正經(jīng)歷著一段艱難的時期。有跡象表明，在現(xiàn)在的西伯利亞附近的構(gòu)造活動產(chǎn)生了火山噴發(fā)的脈沖，與此同時，大約90%的物種消失了。

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.

火山爆發(fā)的證據(jù)可以從地質(zhì)記錄中的化學(xué)變化中找到，而大規(guī)模滅絕的跡象則可以從相對常見的植物化石和動物(如劍尾魚)的迅速減少和機(jī)會主義物種(如豬狀溶血龍)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，也沒有跡象表明會發(fā)生什么不好的事情。這是相對清晰的航行，然后——在地質(zhì)上一眨眼的功夫——一切都亂了套。

"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.

來自加州大學(xué)伯克利分校的古植物學(xué)家辛迪·魯伊說：“大多數(shù)人認(rèn)為，陸地塌陷與海洋塌陷同時開始，南半球和北半球也同時發(fā)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.

從三疊紀(jì)開始到二疊紀(jì)末的劃分標(biāo)準(zhǔn)，是基于中國南方梅山市附近的一個海洋化石層。它的沉積物指出了25196萬年前的一個災(zāi)難性時刻(大約35000年左右)，當(dāng)時水生生態(tài)系統(tǒng)崩潰，約96%的海洋物種滅絕。

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

但它并不是二疊紀(jì)-三疊紀(jì)界線上唯一的權(quán)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.

魯伊帶領(lǐng)研究小組，對埋在南非卡魯盆地原始火山灰樣本中的鋯石晶體中發(fā)現(xiàn)的同位素進(jìn)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.

魯伊說：“卡魯盆地是二疊紀(jì)末脊椎動物更替的典型代表，而直到最近，它仍舊保持著獨(dú)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.

早在二疊紀(jì)，盆地是岡瓦納大陸的一部分。正是在這些南半球的化石記錄中，陸地生物消失的跡象最為明顯。

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，研究小組未能在火山灰正上方的沉積物中發(fā)現(xiàn)來自重要陸地植物物種的花粉，證實了陸地上的生命在沉積后不久就開始衰退。

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.

但是鋯石本身的同位素特征有些奇怪。它表明，這些火山物質(zhì)在那里已經(jīng)存在了2.524億年。

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.

即使考慮到一些回旋的余地，似乎在界定眉山附近邊界的沉積物形成之前，火山灰就已經(jīng)落下了數(shù)十萬年。

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.

要么是弄錯了，要么是二疊紀(jì)大滅絕的過程要慢得多，南方的陸生物種首先消失，而北方的海洋生物則在幾十萬年后才出現(xiàn)。

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.

另一組研究人員今年早些時候發(fā)表了一項基于澳大利亞地質(zhì)學(xué)的類似研究，也指出了陸地物種滅絕的開始時間更早。因此，看起來越來越像偉大的死亡比我們想象的更令人震驚。

This research was published in Nature Communications.

這項研究發(fā)表在《自然通訊》雜志上。