譯/陳韋廷
恐龍時代可能在春天結束
The dinosaur-killing meteor hit in spring.
殺死恐龍的流星是在春天撞擊地球。
That is the conclusion of scientists who examined the bones of fish that died on that day when a 6-mile-wide asteroid collided with Earth.
這是科學家們研究一顆6英里寬小行星撞上地球當天死亡的魚骨，得出的結論。
"These fishes died in spring," said Melanie During, a graduate student at Uppsala University in Sweden and lead author of a paper published in the journal Nature. "The reign of dinosaurs ended in spring."
一篇發表於《自然》期刊論文的主作者、瑞典烏普薩拉大學研究生梅勒妮．杜林說：「這些魚在春天死亡，恐龍的統治在春天結束。」
Scientists have known when the meteor hit — just over 66 million years ago, give or take 11,000 years — and where it hit, off the Yucatán Peninsula of Mexico. That ended the Cretaceous period of Earth's geological history, but even though three-quarters or more of the species of plants and animals disappeared in the mass extinction that followed, it has been hard to pinpoint fossils of anything directly killed by the meteor.
科學家們已經知道這顆流星撞擊時間，大約在6600萬年前，誤差頂多11,000年，撞擊地點則在墨西哥猶加敦半島。這起事件結束了地球地質史的白堊紀時期，但儘管四分之三或更多動植物物種在隨後的大滅絕中消失，卻很難精確找到被流星直接殺死的化石。
But in 2019, paleontologists published the discovery in southwestern North Dakota of what appeared to be a mass graveyard of creatures that died hours or days after the impact. Although North Dakota was about 2,000 miles from where the meteor hit, the seismic waves of what was the equivalent of an earthquake with a magnitude of 10 or 11 sloshed water out of the lakes and rivers and killed the fish. Tektites — small glass beads propelled into the air by the impact — rained from the skies.
但在2019年，古生物學家公布一項在北達科他州西南部的發現，當地似乎是一個在撞擊幾小時或幾天後的生物集體墓地。雖然北達科他州離隕石撞擊地約2000英里，但相當於規模10或11的地震波，讓湖水和河水濺出，殺死了魚類。被沖擊拋至空中的小玻璃珠狀玻璃隕石從天而降。
The researchers spent years exploring the site, known as Tanis, which is in the fossil-rich Hell Creek formation that stretches across four states.
研究人員花了數年時間探索這個被稱為塔尼斯的遺址，當地位在橫跨4個州、富含化石的地獄溪地層中。
With the new science results, the fossils now provide insight into the cataclysm that was previously impossible to discern.
有了新的科學成果，這些化石如今讓我們了解到以前無法辨識出的大災難資訊。
"It's amazing that we can take an event, a single moment that happened 66 million years ago — literally a rock falling down and in an instant striking the Earth — and we can pinpoint that event to a particular time of the year," said Stephen L. Brusatte, a paleontologist at the University of Edinburgh who was not involved in the research. "I think it's a detective story of the highest caliber."
未參與研究的愛丁堡大學古生物學家布魯塞特說：「太棒了，我們可將一個發生在6600萬年前某個時刻的事件，即岩石墜落與瞬間撞擊，確認是在一年中的某個特定時間。我認為這是一部最高水準的偵探小說。」
Animals in the Northern Hemisphere — some emerging from hibernation or giving birth to young — might have been more vulnerable to extinction. "If it was spring, then it was not very likely for many organisms to be in hibernation," During said.
北半球動物有些剛從冬眠中甦醒或剛生下後代，可能更容易滅絕。杜林說：「如果是春天，那麼很多生物不太可能處於冬眠狀態。」
