Sun, Jun 03, 2018 - Page 9 News List

Birds had to relearn flight after meteor wiped out dinosaurs
流星造成恐龍滅絕後 鳥禽重新學飛

Artist’s impression of a 1000km-diameter planetoid hitting a young Earth. Don Davis (work commissioned by NASA)

Photo: Wikimedia Commons

Fossil records suggest only flightless birds survived when T-rex was wiped off the Earth. Birds had to rediscover flight after the meteor strike that killed off the dinosaurs, scientists say.

The cataclysm 66 million years ago not only wiped out Tyrannosaurus rex and ground-dwelling dinosaur species, but also flying birds, a detailed survey of the fossil record suggests. As forests burned around the world, the only birds to survive were flightless emu-like species that lived on the ground.

“Looking at the fossil record, at plants and birds, there are multiple lines of evidence suggesting that the forest canopies collapsed,” said Regan Dunn, a member of the team from the Field Museum in Chicago, US. “Perching birds went extinct because there were no more perches.”

The six to nine-mile-wide meteor struck the Earth off the coast of Mexico, releasing a million times more energy than the largest atomic bomb. Hot debris raining from the sky is thought to have triggered global wildfires immediately after the impact. It took hundreds or even thousands of years for the world’s forests of palms and pines to recover.

Fossil records from New Zealand, Japan, Europe and North America, all show evidence of mass deforestation. They also reveal that birds surviving the end of the Cretaceous period had long sturdy legs made for living on the ground. They resembled emus and kiwis, said the researchers.

“The ancestors of modern tree-dwelling birds did not move into the trees until the forests had recovered from the extinction-causing asteroid,” said Daniel Field, from the University of Bath and a co-author of the paper published in Current Biology. “Today, birds are the most diverse and globally widespread group of terrestrial vertebrate animals — there are nearly 11,000 living species,” he added. “Only a handful of ancestral bird lineages succeeded in surviving the mass extinction event 66 million years ago, and all of today’s amazing living bird diversity can be traced to these ancient survivors.”


1. meteor n.

流星 (liu2 xing1)

2. wipe out phr.

抹除 (mo3 chu2);抹殺 (mo3 sha4)

3. dwell v.

居住 (ju1 zhu4);棲息 (qi xi1)

4. forest canopy phr.

林冠 (lin2 guan4)

5. extinct adj.

絕種 (jue2 zhong3)

6. ecological niche phr.

生態棲位 (sheng1 tai4 qi1 wei4)

The team are now focused on reconstructing the recovery of bird populations and how new species emerged and thrived in the ecological niche left by the extinction of dinosaurs.

(The Guardian)









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