How modern-day dinosaurs survived the apocalypse?

Pedro_P

The mother of all birds lived on the ground.
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When the world of the dinosaurs ended, tree dwellers were at a distinct disadvantage.
Phillip M. Krzeminski

▼ When an asteroid pummeled the  earth66 million years ago, forests burned, molten rock rained over the planet, tsunamis thrashed the coasts, and the sky went dark. Most dinosaursdidn’t outlive the apocalypse that killed off three-quarters of the world’s species, but a few lucky birdssurvived. These creatures all resided on the ground, according to research published this week in Current  Biology.
Because of the near-total global deforestation, tree-dwelling birds didn’t have any place to live, according to the researchers. Only the plucky bunch that conducted their affairs beneath the canopy persisted for future generations, evolvinginto the nearly 10,000 species that exist today.
“Anytime you have a major change with vegetation, you see big changes in everything downstream,” says Regan Dunn, a paleobotanist at the Field Museum in Chicago and one of the study’s authors. Most scientists agree that the reign of dinosaurs ended with the strike of a massive meteor that affected nearly all of life on the globe. “It happened basically in one instant,” Dunn says. “Life as we know it was set.”
Dunn and her colleagues used microscopic fossils of pollenand spores to reconstruct a timeline of plants covering the earth before and after the asteroid. The researchers combined this pollen record with an evolutionary history of birds to show that only ground-dwelling species survived the extinction event.
“You can see this big spike in fern spores,” says Dunn. “That generally means that something has gone terribly wrong in the ecosystem.” The same pattern happens in disturbed habitats today. Volcanic activity in Hawaiiis a good example, says Antoine Bercovici, a pollen expert at the Smithsonian National Museum of Natural History and co-author of the paper. “You see those little fern fiddleheads that peak out of the lava flow,” he says. That’s what happened on a global scale 66 million years ago.
It’s not clear exactly how the asteroid impact annihilated the world’s forests, but there would have a “cacophony of catastrophes,” says Dunn. “It would be have been a horrible day.” (▪ ▪ ▪)

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