在线英语听力室_免费在线英语听力学习网站

This is Scientific American’s 60-Second Science. I’m Steve Mirsky. Got a minute？
The November 26th issue of the journal Science included a study showing that the extinction¹ of the dinosaurs² some 65 million years ago allowed puny³ mammals to get really big. But well before all that happened, another event triggered a different burst of evolutionary⁴ activity.
A new study finds that about 300 million years ago, the tropical rainforests along the equator fell apart. The familiar culprit—global warming.
Present-day Europe and North America were on the equator back then, and were covered with rainforests. But global warming made things even hotter and drier.
The expansive rainforests broke up into smaller fragments, and reptile⁵ populations became isolated⁶ from each other in the fragments. Such geographical⁷ isolation⁸ allows different populations to evolve in different directions, which led to a great increase in reptile diversity. The research appears in the journal Geology. The explosion in reptiles⁹ ultimately led to the evolution of the dinosaurs, which dominated the planet until they fell victim to the massive impact that allowed us mammals to take over. As Vonnegut would say, so it goes.
Thanks for the minute. For Scientific American’s 60-Second Science, I’m Steve Mirsky.