These were the only birds that survived the dinosaur-killing asteroid

When the asteroid that struck the Earth in Chicxulub, Mexico, slammed into the surface some 66 million years ago it made life incredibly difficult for just about every living creature on the planet. It caused massive swings in temperature, and shrouded the Earth in a cloud of darkness which killed off plant life on a massive scale. Now, a new study into the effect the asteroid impact had on bird life is suggesting that the only birds to survive the ordeal were actually ground-dwelling species, but why was that the case?

According to the study, which was published in Current Biology, the diversity of the bird species that survived the impact and immediate aftermath was quite narrow. By studying bird fossils from the period prior to the impact and contrasting that with post-impact fossils, the researchers determined that ground-dwelling birds were the only ones who managed to tough it out, and they think they know why.

Thanks to foliage fossils from the time, scientists know that the asteroid sparked massive fires that wiped out huge sections of forest. The deforestation was so dramatic that it prevented birds from nesting as they normally would. In the centuries following the impact, ferns dominated North America, and tree-dwelling bird species simply couldn’t adjust in time. Ground-dwelling, quail-like birds on the other hand were better equipped to deal with this new landscape.

The researchers say that only a handful of modern bird types were actually around prior to the asteroid’s arrival, including the ancient ancestors of chickens and ducks. Gathering their food from the ground rather than finding it by air, these primitive birds were able to hang on against all odds.

However, as Science magazine points out, some researchers aren’t so ready to accept these dramatic findings. Some have suggested that the scientists behind the work are trying to draw broad conclusions from a smattering of evidence. “It’s a debate that’s been going on for decades,” Joel Cracraft of the American Museum of Natural History in New York City notes. “I don’t think it’s going to end any time soon.”