animal kingdom

How the mass extinction event that killed dinosaurs gave us the majority of frogs alive today

Nearly 90% of the short-bodied, tailless amphibians roaming our planet right now first appeared in the years following the cataclysmic event.

There are three orders in the class Amphibia, collectively comprising nearly 7,700 species. Of those three, the order Anura, which includes frogs and toads, represents 6,787 of the world’s known amphibian species, spread across 55 families.

It’s believed that frogs diverged from the other orders of amphibians – Caudata, or salamanders, and Gymnophiona, or caecilians (snake-like amphibians with no limbs who live mostly underground, which is why most people haven’t heard of them) – some time during the Palaeozoic Era or early Mesozoic Era, before the super-continent Pangaea broke up into the major land masses we are familiar with today.

Based on fossil records and the available genetic data, scientists have generally estimated that modern frog species first began to appear at a steady pace between 150 million and 66 million years ago. But new research published in the Proceedings of the National Academy of Sciences suggests that the timeframe was actually much tighter than that.

The mass extinction event that occurred 66 million years ago, during the Cretaceous Period at the end of the Mesozoic – when the dinosaurs were wiped out by an asteroid that collided with Earth – actually spurred something of an explosion of new frog species. Nearly 90% of the short-bodied, tailless amphibians roaming our planet right now first appeared in the years following the cataclysmic event that caused all dinosaurs but birds to go extinct, according to the study.

An international team of scientists with The University of Texas at Austin, the University of California, Berkeley, the Florida Museum of Natural History, and China’s Sun Yat-Sen University analysed genetic samples that they gathered from 156 frog species together with previously published data on 145 others. The team studied variations in 95 genes, whereas most studies look at just a dozen or less, in order to construct the most complete frog family ever created.

Population boom

The researchers say they found evidence that there were three separate booms of new frog species that occurred on three different continents following the mass die-off of the dinosaurs. While most frogs alive at the time were also wiped out, the researchers theorise that, with so many other species having disappeared, there were suddenly an abundance of new ecological niches that the surviving frogs could fill. Moving into all of those different habitats essentially jump-started the evolutionary process and allowed for rapid frog diversification.

“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,” David Hillis, a professor of integrative biology at UT Austin and a co-author of the Proceedings of the National Academy of Sciences study, said in a statement. “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.”

Hillis and team determined that three clades in particular – Hyloidea, Microhylidae, and Natatanura, which collectively comprise 88 percent of Anura species – underwent rapid diversification during a period known as the Cretaceous-Paleogene boundary, which marks the end of the Cretaceous Period and the start of the Paleogene Period, the first period of the Cenozoic Era. The researchers also discovered that frog families and subfamilies containing arboreal species originated “near or after” the Cretaceous-Paleogene boundary.

“These results suggest that the [Cretaceous-Paleogene] mass extinction may have triggered explosive radiations of frogs by creating new ecological opportunities,” they write in the Proceedings of the National Academy of Sciences study.

The team’s findings bolster those of a 2015 study by another team of scientists at UT Austin who used computer simulations to show that mass extinctions can accelerate evolution as animals spread into and adapt to new habitats. “Even destruction can be leveraged for evolutionary creativity,” Joel Lehman, a co-author of that study, said in a statement.

A tree frog (genus Boophis) found on Madagascar and Mayotte Island, off the Southeast coast of Africa. Photo credit: Brian Freiermuth/Univ. of Florida.
A tree frog (genus Boophis) found on Madagascar and Mayotte Island, off the Southeast coast of Africa. Photo credit: Brian Freiermuth/Univ. of Florida.

This article first appeared on Mongabay

Support our journalism by subscribing to Scroll+ here. We welcome your comments at letters@scroll.in.
Sponsored Content BY 

Can a colour encourage creativity and innovation?

The story behind the universally favoured colour - blue.

It was sought after by many artists. It was searched for in the skies and deep oceans. It was the colour blue. Found rarely as a pigment in nature, it was once more precious than gold. It was only after the discovery of a semi-precious rock, lapis lazuli, that Egyptians could extract this rare pigment.

For centuries, lapis lazuli was the only source of Ultramarine, a colour whose name translated to ‘beyond the sea’. The challenges associated with importing the stone made it exclusive to the Egyptian kingdom. The colour became commonly available only after the invention of a synthetic alternative known as ‘French Ultramarine’.

It’s no surprise that this rare colour that inspired artists in the 1900s, is still regarded as the as the colour of innovation in the 21st century. The story of discovery and creation of blue symbolizes attaining the unattainable.

It took scientists decades of trying to create the elusive ‘Blue Rose’. And the fascination with blue didn’t end there. When Sir John Herschel, the famous scientist and astronomer, tried to create copies of his notes; he discovered ‘Cyanotype’ or ‘Blueprints’, an invention that revolutionized architecture. The story of how a rugged, indigo fabric called ‘Denim’ became the choice for workmen in newly formed America and then a fashion sensation, is known to all. In each of these instances of breakthrough and innovation, the colour blue has had a significant influence.

In 2009, the University of British Columbia, conducted tests with 600 participants to see how cognitive performance varies when people see red or blue. While the red groups did better on recall and attention to detail, blue groups did better on tests requiring invention and imagination. The study proved that the colour blue boosts our ability to think creatively; reaffirming the notion that blue is the colour of innovation.

When we talk about innovation and exclusivity, the brand that takes us by surprise is NEXA. Since its inception, the brand has left no stone unturned to create excusive experiences for its audience. In the search for a colour that represents its spirit of innovation and communicates its determination to constantly evolve, NEXA created its own signature blue: NEXA Blue. The creation of a signature color was an endeavor to bring something exclusive and innovative to NEXA customers. This is the story of the creation, inspiration and passion behind NEXA:

Play

To know more about NEXA, see here.

This article was produced by the Scroll marketing team on behalf of NEXA and not by the Scroll editorial team.