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Springing to extinction
恐龙是在哪个季节灭绝的？
Imagine a warm spring day 66 million years ago.
想象一下6600万年前一个温暖的春天。
Fish would have been swimming in the rivers in an area that’s now North Dakota in the US.
在位于现今美国北达科他州区域的河流中，鱼儿畅游着。
Seconds later, the serenity was ended by destruction.
几秒钟后，毁灭终结了这份宁静。
These could have been the very last moments of the dinosaur era when a city-sized asteroid struck Earth,
这也许是恐龙时代的最后时刻，因为一颗城市大小的小行星撞击地球，
killing off three quarters of all species on the planet.
杀死了地球上四分之三的物种。
According to a study published in Nature on Feb 23, the asteroid hit in springtime.
根据2月23日《自然》杂志上发表的一项研究，小行星撞击地球是在春季。
Scientists have long been confused over the time of year the asteroid hit,
长期以来，科学家们一直对小行星撞击地球的时间困惑不清，
and how some animals managed to survive while dinosaurs didn’t, according to USA Today.
也搞不懂一些动物是如何存活下来，而恐龙却未能活命的,据《今日美国》报道。
Researchers in 2019 discovered fossilized fishes in North Dakota that died shortly after the asteroid hit Earth.
2019年，研究人员在北达科他州发现了鱼类化石，这些鱼类在小行星撞击地球后不久死亡。
They examined the fossils with a particle accelerator and found out there was seasonal growth on the bones.
研究人员用粒子加速器检查了化石，发现鱼骨上显示出季节性生长。
All fish bone cell densities and volumes can indicate the season.
所有的鱼骨细胞密度和体积都可以表明季节。
Because the accelerator also could capture the sizes,
由于加速器还能捕捉到小行星的大小，
researchers were able to determine when in the year the asteroid hit,
研究人员因此能够确定小行星撞击地球在一年中的具体时间。
Dennis Voeten, a researcher at Uppsala University in Sweden told USA Today.
瑞典乌普萨拉大学的研究员丹尼斯·沃滕在接受《今日美国》采访时表示，
The timing of the collision, at least for the Northern Hemisphere, came at a particularly sensitive stage.
小行星撞击地球的时间，至少对于北半球来说，是一个特别敏感的阶段。
“I think spring puts a large group of the late Cretaceous biota in a very vulnerable spot because they were out and about looking for food,
“我认为春天令一大群晚白垩纪生物处在了一个非常脆弱的境地，因为它们忙着外出寻找食物，
tending to offspring and trying to build up resources after the harsh winter,”
照顾后代，在严冬后累积一些资源。”
Melanie During, the main author of the study, said at a news briefing.
这项研究的主要作者梅勒妮·杜林在一次新闻发布会上说：
In the Southern Hemisphere, it was autumn, a season when many creatures prepare for winter.
南半球正值秋天，这是许多生物准备过冬的季节。
Therefore, life in the Southern Hemisphere was a lot more prepared for this event.
因此，南半球的生命对这一事件有了更充分的准备。
It is unclear whether small animals in the Northern Hemisphere actually did worse than those in the south.
目前尚不清楚北半球的生物是否真的比南半球生物表现更糟。
There is evidence that Northern Hemisphere turtles were wiped out in the asteroid strike,
沃滕在接受《卫报》采访时表示，有证据表明，北半球的海龟在小行星撞击中灭绝了，
after which their habitats were later repopulated by turtles from the south, Voeten told The Guardian.
之后它们的栖息地又为来自南半球的海龟所重新占据。
Nothing much larger than a house cat survived the asteroid impact and many species would have been doomed whenever it hit,
体型比家猫大的动物没能在小行星撞击地球时幸存下来，无论何时，撞击一旦发生，许多物种就难逃厄运。
Daniel Field, an assistant professor at the University of Cambridge in the UK, told The Guardian.
英国剑桥大学助理教授丹尼尔·菲尔德在接受《卫报》采访时表示。
