A new study, which the journal Current Biology recently published, might have some answers to that mystery. Landing in the Yucatan peninsula, Mexico, it created a vast crater in the ground. During the initial impact, shock waves flattened trees in massive waves within a radius of almost 1,000 miles. Vapor, rich in sulfates, triggered acid rain. With soot completely blanketing the atmosphere, plants were unable to grow back. Any birds that roosted or set down in trees would've been homeless. This includes data from massive new family trees for living birds, clues from newly discovered fossil birds, and an analysis of spores and pollen from the rock layer laid down immediately following the impact.
But dinosaurs weren't the only ones that got hit hard-in a new study, scientists learned that the planet's forests were decimated, leading to the extinction of tree-dwelling birds. "It speaks to the power of collaborative science, and the importance of the fossil record for understanding the life in the modern world". No trees meant no homes for flying birds, so they all died while their non-flying cousins survived on the ground. Many small-bodied birds today eat insects, and this trait can be traced to the surviving birds 66 million years ago.
All birds are said to be from an emu-like bird which could not fly.
This seems to match with their reconstructions, which show that the birds that survived the extinction event had ground-dwelling features, such as relatively long legs.
Every bird alive today is descended from these emu-like ancestors, the scientists believe.
"The end-Cretaceous event is the fifth mass extinction - we're in the sixth", said Dunn.
The ground-dwelling birds that made it through would not have had a simple presence.
Ferns were likewise the huge survivor, rather than trees, since their small, single-celled spores distributed rapidly. That's because ferns don't sprout from seeds, but from spores, which are much smaller-just a single cell.
North, South Korean Leaders Hold Second Meeting in Demilitarized Zone
On Thursday US President Donald Trump cancelled the summit, scheduled for 12 June, but later suggested it might still go ahead. Bloomberg's Kevin Cirilli reports on Trump's latest comments about meeting North Korean leader Kim Jong Un .
Dr Regan Dunn, a member of the team from the Field Museum in Chicago, US, said: "Looking at the fossil record, at plants and birds, there are multiple lines of evidence suggesting that the forest canopies collapsed".
So the length of time would it take the ferns to prosper?
It may have taken thousands of years for mature forests to return, the researchers say, and their composition was forever changed.
'The ancestors of modern tree-dwelling birds did not move into the trees until forests had recovered from the extinction-causing asteroid'. "By a couple of millions of years after the asteroid impact, we have direct evidence of arboreal fossil birds".
Studying whole paleoecosystems shows how life on Earth has evolved through all the trials and tribulations of the past, Dunn said in an email.
" Human activity is triggering logging on an enormous scale", Field stated.
MacLeod painted a bleak picture: "Anything that's not killed by the thermal heat pulse likely had to deal with years of very little, if any, vegetation, and anything that survived that then had to survive 100,000 years of quite substantial greenhouse conditions".