The asteroid that killed the dinosaurs also shaped the evolution of birds

Scientists who study plant life around the extinction event that killed the dinosaurs have made a surprising discovery: of all the birds that lived at that time, only the species that inhabit the soil survived.

The finding, described in the journal Current Biology, reveals how poultry winners and losers in the wake of the Cretaceous-Paleogene extinction event formed the evolution of all the birds we see today.

The asteroid that hit the Earth 66 million years ago was 93 miles wide The killer rock crashed into the Yucatan Peninsula with such force that it razed the trees within a radius of 930 miles and radiated so much heat that it probably ignited forest fires around the world, said the study authors. Not to mention the acid rain and the release of so much soot that turned off the sunlight, starving the photons they needed to make food and causing a significant cooling of the climate.

"This phase of repressed sunlight, notoriously difficult to reconstruct, is supported by the proliferation of saprotrophs that thrive in the decomposition of organic matter," the study authors wrote.

The dinosaurs were completely exterminated, except for their descendants, the birds, who recovered and diversified. Tiny floating hummingbirds, huge albatrosses, ostriches that live on the ground, marine penguins and all the feathered creatures in the middle owe their existence to the birds that survived that extinction event.

Scientists have wondered if some birds were successful while others succumbed and what gave them advantage to those particular survivors. Some have suggested that those with toothless peaks were better at eating seeds and grains, which would have survived more easily in the apocalyptic landscape than the plants that created them. But previous work has shown that animals with jagged bills were also able to eat seeds. Others have pointed out that a post-asteroid world probably favored smaller birds over larger ones, partly because they would need less food to survive. Such factors may have played a role, but they do not offer a full explanation, the researchers said.

For this document, an international team of scientists used statistical methods to reconstruct the ancient ancestors of live bird groups. They combined it with a study of the fossil plant and the spore record, in an effort to see what survived the asteroid and what did not.

  Bird after the asteroid "title =" Bird after the asteroid "/> 
<figcaption> The birds that survived after an asteroid killed the dinosaurs had several features in common.As shown in this illustration, they were small and They lived mainly on the ground. <span clbad= Phillip M. Krzeminski

Scientists discovered that there was an increase in the number of fern spores after the asteroid hit.It is a revealing discovery because ferns tend to take control when It has leveled a forest canopy.

"Ferns are pioneering colonizers of devastated landscapes, and their proliferation represents a clbadic example of a 'flora of disaster & # 39; composed of taxa capable of germinating rapidly from spores and rhizomes and / or roots, "wrote the authors of the study.

The trees, then, must have been lost, any bird that had to live exclusively in those trees, the they say, they would have died out too.

This seems to coincide with their reconstructions, which show that the birds that survived the extinction event had soil characteristics, such as relatively long legs, only after the forests began to resurface. birds could begin to fill "arboreal" niches once more.

"The numerous independent transitions towards arboreality through the tree of life neomalithin – including ancient transitions within larger clades such as Strisores (hummingbirds, nightjars, and relatives) , Otidimorphae, Columbimorphae (pigeons and relatives) and Inopinaves – occurred after the K-Pg transition, presumably after is that the global forests had recovered from their devastation after the impact of the asteroid, "wrote the authors of the study. [19659002Scientistspointedoutthatthefindingsmayhelpresearcherstobetterunderstandtheevolutionofbirdsandreducethecurrentinaccuratestatusofbirdswhosepopulationshavebeenthreatenedbyhumanactivity

"Today, the diversity of the avian community is negatively influenced by loss of plant diversity and habitat due to human activity, including monospecific agriculture and land-use patterns," they wrote, "and the floral phase of low diversity arly-Paleocene may have affected similarly to the poultry communities at that time. "

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