Study Finds Frogs Flourished After Dinosaur Extinction

(CN) – New research shows that the mass die-off of dinosaurs and many other species also sparked an explosion of new frog breeds – a surprising relationship that reinforces the theory that mass extinctions can lead to surges of evolutionary activity.

Reconstructing an accurate family tree for frogs has been difficult due to limited genetic data. Along with clues from the fossil record, existing evidence had suggested that most modern frog species slowly began to appear about 150 to 66 million years ago.

However, this explanation appears to be invalidated by a new study that presents the most complete frog family tree yet, which researchers developed by analyzing the genetic samples of more than 300 frog species.

The report, published this week in the journal Proceedings of the National Academy of Sciences, shows that while the mass extinction 66 million years ago wiped out most frog species – along with about 75 percent of all plant and animal species alive then – the die-off offered new ecological settings for the remaining frogs to spread into. This, in turn, fueled their rapid diversification, according to the study.

“We know that mass extinction events 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,” said study co-author David Hillis, a professor at the University of Texas at Austin. “As we look at more and more groups of life, we see the same pattern, and that turns out to be the best case for frogs as well.”

The team collected genetic samples from 156 frog species and combined them with previously published data on 145 more species. For the new samples, the scientists examined variations in 95 genes – compared to past research that used only five to 12 – to establish a more detailed understanding of how the species relate to one another.

Today, there are more than 6,700 known frog species that live in a variety of habitats, ranging from trees to underground environments.

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