科学美国人60秒 SSS 2014-09-22

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  You  have to think not only about the charismatic animals which are walking on the planet but also all the resources on which those animals are depending.

  Say, for example, vegetation. Blunder has been giving those overshadowed impact victims their due. After all, more than half  the planet's species in temporary North America periched along with the dinosours. And the type of plants that thrived after the impact were different as well. Blunder and his colleagues studied thousands of fossile leaves from North Dokotar, spanning about a million years both before and after the impact. They measured the leaf mass per area, a proxy² for how much energy a plant invests in its leaves, and density³ vein⁴ s, which indicates how fast growing the leaf is. Sturdy, slow-growing leaves tend to  be ever-greens, whereas the flimsy, fast-growing leaves are hall marks of decidous plants. Turns out that after the impact the fossile records have more deciduously looking leaves, suggesting that fast-growing, more adaptable⁶ seasonal⁷ plants beat out the competition after the big hit. The study appears in the journal" Plus Biology". And it kind of made me wonder if we have overlooked another theory for why the dions died out. Maybe they just didn't care for the taste of the deciduous⁵ leaves.

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