Insect bites on fossilized leaves have finally helped us solve a long-standing mystery around the meteor that wiped out the dinosaurs about 66 million years ago. For years, scientists thought that the meteor hurt North America more, making South America a refuge for the species that survived. But by analyzing insect damage, we now know that the meteor hurt both hemispheres badly — it’s just that the Southern Hemisphere recovered much more quickly.
Insect damage on leaves is one common way to learn more about the food web and the general ecosystem of an area. Generally, more diverse insect bites suggest a richer ecosystem. A team of scientists led by Michael Donovan at Pennsylvania State University decided to compare the insect damage both before and after the dinosaur-killing meteor. That meteor hit our planet in today’s Yucatan peninsula in Mexico, unleashing a global mass extinction.
To learn more about the claim that South America wasn’t affected as badly, the team focused on nearly 4,000 fossilized leaves from a region of Argentina called Patagonia. Their paper was published today in Nature Ecology & Evolution.
It turns out that the meteor likely hurt South America just as badly as North America, because no insect species from before the event survived. This suggests that it’s unlikely that the continent actually served as a refuge for any species fleeing the North.
By looking at the various insect damage on leaves after the meteor, the team also found that the full diversity of insects — and by extension, the ecosystem — was restored about 4 million years after impact. That sounds like a long time, until you realize that it took 9 million years for North America to recover. (It’s probably because South America recovered so quickly that we thought that it originally wasn’t affected so badly.)
We still don’t know exactly why South America recovered so quickly; the authors say it’s probably a combination of distance from the crater and “other, poorly understood factors.” Still, just knowing about South America’s impressive recovery is the first step to finding out why, and then further unraveling all the effects of this long-ago meteor.