How Did Dino-Era Birds Survive the Asteroid 'Apocalypse'?


On a very bad day 66 million years ago, a mountain-sized object from space slammed into Earth, initiating a cascade of calamities that eradicated three-fourths of the species on the planet, including the non-avian dinosaurs. The event was called the Cretaceous-Paleogenic Extinction Event and only after the discovery of the Chicxulub Crater in 1978 scientists started to research. Any birds that roosted or perched in trees would've been homeless. "We concluded that the temporary elimination of forests in the aftermath of the asteroid impact explains why arboreal birds failed to survive across this extinction event".

A team of scientists found this by examining fossil plant remains and the ecological makeup of ancient and modern birds and they think it is due to the impact of the asteroid that decimated the forests all over the world that lasted hundreds and even thousands of years to be restored. "By a couple of millions of years after the asteroid impact, we have direct evidence of arboreal fossil birds".

Field and his coauthors compiled a mass of evidence from disparate sources to help support their argument.

"The study came together bit by bit", says Field. They then tracked the evolutionary relationship of birds and how bird ecology changed over their existence.

"Today, birds are the most diverse and globally widespread group of terrestrial vertebrate animals-there are almost 11,000 living species", says Field. The ground-dwelling birds basically got over and the rest of the birds of today evolved from them. The aftereffects of the Chicxulub impact remain debated, with some scientists advocating that soot within the atmosphere blocked out the sun sufficiently to drive global cooling; others suggest that carbon released from the Earth's crust into the atmosphere upon the asteroid's impact, as well as carbon from wildfires, had a warming effect.

Additional co-authors of the study are Antoine Bercovici of the Smithsonian Institution, Jacob Berv of the Cornell Lab of Ornithology, Regan Dunn of the Field Museum of Natural History, Tyler Lyson of the Denver Museum of Nature and Science, David Fastovsky of the University of Rhode Island, and Vivi Vajda of the Swedish Museum of Natural History.

And even though the asteroid collided with Earth around 66million years ago, the sudden global warming that followed is relevant to what's happening today, experts said.

With no more trees, the tree-dwelling birds went extinct. None of these birds survived, which the authors surmise was because their habitat had entirely vanished.

During this period, this had a large impact on the evolution of birds and the ancestors of the current species of birds.

"These observations are consistent with the idea that ground-dwelling lineages survived across the end-Cretaceous boundary, and then repeatedly took to the trees once global forests had rebounded", Field says.

MacLeod's team now want to look at fossil samples from other parts of the world and check for similar patterns. "We understand that the variety of bird neighborhoods is affected by the schedule of forests- when forests are lowered in favor of, for instance, palm oil monoculture, bird variety is slashed".

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