快猫短视频

40 years ago, 快猫短视频 was pondering whether the dinosaurs met a cataclysmic end

THE story might almost have begun with 鈥渙nce upon a time鈥�. 鈥淎bout 65 million years ago, at the end of the Cretaceous Period, a wayward Apollo-type asteroid ploughed into our planet and was responsible for wiping out the dinosaurs and many other forms of life on Earth,鈥� we wrote in our 10 January 1980 issue.

Our correspondent was reporting from the annual meeting of the American Association for the Advancement of Science in San Francisco. There, a team of California-based scientists led by Nobel prize-winning physicist Luis Alvarez and his geologist son Walter Alvarez first publicly proposed a truly Earth-shattering explanation for one of life鈥檚 most enigmatic episodes 鈥� a mass extinction that had apparently wiped out many of the planet鈥檚 species, including the then-dominant dinosaurs.

鈥淭he theory is supported by the discovery of large concentrations of iridium in rocks from the Gubbio Valley in Italy and near Copenhagen in Denmark,鈥� we wrote. The sheer amount of this element, rare on Earth but relatively abundant in some space environments, suggested the impact of an extraterrestrial rock 7 to 10 kilometres in diameter, the team proposed.

The 100 million megaton explosion 鈥渨ould make a 175 km diameter dent in the crust and material 100 times the object鈥檚 mass would be thrown skyward. The resulting darkness would suppress photosynthesis, and give rise to the pattern of extinctions observed in the fossil record,鈥� we wrote.

This compelling story was bolstered in the early 1990s by the discovery of the 150-kilometre-wide Chicxulub crater, found partially on Mexico鈥檚 Yucat谩n peninsula and partially under the sea to the north. Not only was the crater about the right size, but the site also proved rich in iridium, providing conclusive evidence that the clay layer on the Cretaceous鈥揚aleogene boundary represented debris from an asteroid impact.

Too good to be true? A cartoon accompanying our initial report wondered whether the whole idea had been invented by Hollywood. There are some who still nurse that suspicion, casting doubt on whether the precise timing of the impact means it can be responsible. But for most, the seemingly science-fiction tale of a space rock doing for the dinosaurs is now firmly established as science fact.