Frogs survive what sent dinosaurs into extinction

The global catastrophe that killed off dinosaurs was good news for frogs, scientists have discovered.

According to new research, 88% of frog species living today owe their existence to the meteor impact that wiped out most terrestrial life 66 million years ago.

Almost nine out of 10 of the amphibian species descended from just three lineages that survived the mass extinction.

They each jumped forward precisely at the junction of the Cretaceous and Paleogene periods – formerly known as the KT boundary – when the disaster happened.

Scientists believe the first survivors may have escaped the meteor strike by burrowing underground.

Research had previously suggested that the evolution of frogs started 35 million years earlier and had nothing to do with the dinosaur apocalypse.

Study co-author Professor David Hillis, from the University of Texas at Austin, US, said: “We know that the mass extinction event wiped out most of the dinosaurs, except for a few bird species, which then exploded in diversity and became one of the dominant groups of land animals.

“As we look at more and more groups of life, we see the same pattern, and that turns out to be the case for frogs as well.”

Professor David Wake, from the University of California at Berkeley, said a major factor in early frog evolution was the way the creatures adapted to living in trees as flowering plants spread across the planet.
Many species of frog are under threat
He said: “Frogs started becoming arboreal. It was the arboreality that led to the great radiation in South America in particular.”

In their report published in the Proceedings of the National Academy of Sciences publication, the researchers said trees are an ideal habitat for frogs not only because they provide a refuge from terrestrial predators, but also leaf cover on the ground, and abundant insects for food.

The scientists, from America and China, made the discovery after analysing genetic data from frogs within 44 living families.

There are more than 6,700 known frog species but they are threatened by habitat destruction, increasing human population and climate change.

Prof Wake added: “These frogs made it through on luck, perhaps because they were either underground or could stay underground for long periods of time.

“This certainly draws renewed attention to the positive aspects of mass extinctions: they provide ecological opportunity for new things.

“Just wait for the next grand extinction and life will take off again. In which direction it will take off, you don’t know.”

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