The Cretaceous period was coming to an end almost 66 million years ago when an asteroid as huge as Mount Everest crashed into the Earth. Landing in the Yucatan peninsula, Mexico, it created a vast crater in the ground. The crash created a chain reaction and affected the environment, leading to the disappearance of dinosaurs. But the feathered dinosaurs somehow survived.
Almost 150 million years ago, birds started to evolve from smaller dinosaurs that looked like Velociraptors. At the end of Cretaceous, they started to flourish, but the asteroid almost killed them off. Many large groups of ancient feathered birds disappeared. However, the ones surviving started to evolve and adapt.
This is how the modern birds started to appear. But which ones survived and how did they do it?
Evolving And Adapting
Daniel Field, from the University of Bath and his colleagues found new information on a subject not much discussed so far:
“A lot of people have focused quite intensively on trying to understand what went extinct. But we know very little about how or why birds managed to sneak across.”
He and his colleagues found out that most of the birds that survived the mass extinction were birds that lived on the ground, like our modern day chickens. The ones that lived in the trees had no chance to survive with everything being on fire and no place to nest.
The ancient bird that led to such a great diversity today was, according to Field’s team, “almost certainly a ground-dwelling bird.” He also explained that the ground-dwelling birds could fly, but simply chose not to – just like today’s birds in Central and South America. A short period after the asteroid hit the Earth, some of the ground-dwelling birds took to the trees, replacing the ones that didn’t survive the crash.
Pollen and Fern Spore Fossils
Looking at fossilized pollen grains and spores of ferns, and knowing that after the crash fires over fires started to spread all over the Earth, causing perpetual nights from the ash and acid rain, the team estimated that it took the forests almost 1000 years to recover and allow birds to readapt.
Zhonghe Zhou works at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), in Beijing. He suggests that Field’s hypothesis needs more fossil evidence to prove it. However, a colleague at the IVPP stated:
“It’s a great idea. But we need to get over this one-answer-for-everything way of thinking. No one factor caused the end-Cretaceous extinction and similarly no one factor caused the extinctions within [the birds]. Forest loss was only one of several factors working in combination that determined which bird lineages survived.”
Andre Blair s is the lead editor for Advocator.ca. He holds a B.A. in Psychology from the University of Toronto, and a Master of Science in Public Health (M.S.P.H.) from the School of Public Health, Department of Health Administration, at the University of North Carolina at Chapel Hill. Andre specializes in environmental health, but writes on a variety of issues.