How frogs flourished after dinosaurs croaked, reveals study
An asteroid strike that wiped out dinosaurs, millions of years ago has created a place for frogs to colonize the Earth, a study showed today how frogs have become the richest vertebrate in the world.
It is estimated that about 10 types of frogs survived the mass extinction that is about 66 million years old, which has erased three quarters of life on Earth, according to the report in the Proceedings of the National Academy of Science.
Among these survivors, only three major types of frogs are diverse and populated the world. There are some 6,700 known species of frogs today.
Almost nine out of every 10 – 88 percent – of modern frogs can find their roots in these three cunning lines of ancestors.
“Frogs were carried out for over 200 million years but this study shows that it is only dinosaurs that we had this explosion of diversity of frogs that resulted in the vast majority of frogs we see today,” said the study Co-author David Blackburn, associate curator of amphibians and reptiles at the Florida Museum of Natural History.
“This discovery was totally unexpected.”
Until now, scientists thought that most modern frog species appeared at a steady pace between 66 million and 150 million years ago.
However, recent research shows that frogs explode on a scene as an “explosion” because small amphibians swept the habitats left vacant by other creatures.
For the study, researchers in China and the United States have compiled the largest collection of genetic data on frogs ever evaluated.
The genetic samples were collected from 156 species of frogs and combined with previously published data on 145 species.
Previous studies have examined five to 12 genes, while the current examined variations in 95 genes, providing a much more detailed examination of the relationship between different species.
The researchers also looked at the fossil record to determine when different types of frogs probably diverged from each other.
The researchers found “evidence of one but three bursts of new species of frogs on different continents, and all were concentrated after the mass death of most dinosaurs and many other species of about 66 million years,” according to the report.
Two of the three lines of survivors – Microhylidae and Natatanura – left Africa. The third Hyloidea, extended by all that today is South America.
“These frogs have been an opportunity, perhaps because they were underground or could remain underground for long periods of time,” said co-author David Wake of the University of California.
“Undoubtedly, it draws attention to the positive aspects of mass extinctions: they offer ecological opportunities for new things.”
Similar evolutionary events occurred with birds, said co-author David Hillis, a professor of integrative biology at the University of Texas at Austin.