The mass extinction event 66 million years ago that wiped out three-fourths of the life on Earth, including dinosaurs, helped pave way for the swift rise of frogs, a study has found.
Researchers found a new tree of life for frogs that helps solve longstanding riddles about relationships and sheds light on the history and pace of frog evolution.
The analyses showed three major lineages of modern frogs - about 88 per cent of living species - appeared simultaneously, evolving on the heels of the extinction event that marked the end of the Cretaceous Period and the beginning of the Paleogene 66 million years ago.
Previous research suggested a more ancient origin of many of these modern frog groups.
"Frogs have been around for well over 200 million years, but this study shows it wasn't until the extinction of the dinosaurs that we had this burst of frog diversity that resulted in the vast majority of frogs we see today," said David Blackburn, from the Florida Museum of Natural History in the US.
The speed at which frogs diversified after the asteroid or comet impact that triggered a massive die-off of most plant and animal life suggests that the survivors were probably filling up new niches on Earth, Blackburn said.
"We think there were massive alterations of ecosystems at that time, including widespread destruction of forests," he said.
"But frogs are pretty good at eking out a living in microhabitats, and as forests and tropical ecosystems rebounded, they quickly took advantage of those new ecological opportunities," he added.
Frogs rose to become one of the most diverse groups of vertebrates, with more than 6,700 described species.
However, sparse genetic data has hindered scientists from reliably tracing their evolutionary history and the links between frog families.
Researchers tackled the mystery of frog evolution with a dataset seven times larger than that used in prior research.
The team sampled a core set of 95 nuclear genes from 156 frog species, combining this with previously published genetic data on an additional 145 species to produce the strongest- supported evolutionary tree, or phylogeny, to date.
The tree represents all 55 known families of frogs and generates a new timeline of frog evolution.
The researchers then used fossil records to translate genetic differences between frog lineages into dates at which they likely diverged from one another.
The analyses pointed to a simultaneous evolution of the three major frog clades - Hyloidea, Microhylidae and Natatanura.
The close resemblance of distantly related frog species around the world, a factor of frog evolution and biology that has long confounded scientists, might be illuminated by the simultaneous evolution of major frog clades, Blackburn said.
After the extinction event decimated ecosystems and stimulated a reset, modern frogs may have faced similar evolutionary paths.
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