Dino Devastator Also Ravaged Veggies

时间 : 2014-09-28 08:59来源 : VOA官网 收听下载次数 :
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Sixty-six million years ago, the Chicxulub meteorite, a rock over six miles wide, slammed into the Earth. And you know what happened next—the dinos disappeared. But Benjamin Blonder, a plant ecologist at the University of Arizona, says to consider the big picture for a moment.

"You have to think not only about the charismatic animals which are walking on the planet, but also all of the resources on which those animals are depending." Say, for example, vegetation. Blonder has been giving those overshadowed impact victims their due. After all, more than half the plant species in temperate North America perished along with the dinosaurs.

And the type of plants that thrived after the impact were different as well. Blonder and his colleagues studied thousands of fossil leaves from North Dakota, spanning about a million years both before and after the impact. They measured leaf mass per area, a proxy for how much energy a plant invests in its leaves, and the density of veins, which indicates how fast-growing the leaf is. Sturdy, slow-growing leaves tend to be evergreens, whereas flimsy, fast-growing leaves are a hallmark of deciduous plants.

Turns out that after the impact, the fossil record has more deciduous-looking leaves—suggesting that fast-growing, more adaptable seasonal plants beat out the competition after the big hit. The study appears in the journal PLoS Biology. [Benjamin Blonder et al, Plant Ecological Strategies Shift Across the Cretaceous–Paleogene Boundary]

And it kinda makes me wonder if we haven't overlooked another theory for why the dinos died out—maybe they just didn't care for the taste of deciduous leaves?

—Christopher Intagliata