Photo by David Clode on Unsplash
Photo by David Clode on Unsplash

As the dinosaurs died, snake diversity exploded

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Peer-reviewed: This work was reviewed and scrutinised by relevant independent experts.

The loss of dinosaurs was good news for snakes with the population exploding in diversity following dinosaur extinction, according to international research. Previous research shows the demise of the dinosaurs triggered major diversification in mammal and bird species on the earth, and researchers created mathematical models that looked at the diets of nearly 900 modern snake species to see if this was the case for them too. The researchers say other flourishing new bird and mammal species quickly became food for snakes that had previously only ate insects, causing an evolutionary chain reaction.

Journal/conference: PLOS Biology

Link to research (DOI): 10.1371/journal.pbio.3001414

Organisation/s: University of Michigan, USA

Funder: This research was supported by a Graduate Research Fellowship (DGE 1841052) from the National Science Foundation to M.C.G. and by a fellowship from the David and Lucile Packard Foundation to D.L.R. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Media release

From: PLOS

Snakes diversified explosively after the dinosaurs were wiped out

Sudden burst of evolution 66 million years ago expanded snake diets and put vertebrates on the menu

The remarkable diversification of mammals and birds after the demise of the dinosaurs 66 million years ago is well known; but what happened to the snakes? According to a study publishing October 14th in the open-access journal PLOS Biology by Michael Grundler at the University of California, Los Angeles and Daniel Rabosky at the University of Michigan, snakes experienced a similarly spectacular burst of evolution from unassuming insectivorous ancestors to diverse lineages that included the newly available birds, fish and small mammals in their diets.

The K-Pg mass extinction event 66 million years ago – during which 75% of species, including all non-avian dinosaurs, went extinct – marked the beginning of the Cenozoic era and opened a myriad of empty niches for the surviving species to exploit. Like mammals and birds, snakes diversified rapidly during the Cenozoic era, resulting in the nearly 4,000 species that we see today.

To better understand the pace and sequence of this phenomenon, the researchers collated published data on the diets of 882 living snake species and used sophisticated mathematical models to reconstruct how the diets of their ancestors changed and diversified since the K-Pg boundary. They found that the most recent common ancestor of living snakes was insectivorous, but after the K-Pg boundary, snake diets rapidly expanded to include birds, fish, and small mammals – vertebrate groups that were also flourishing in the wake of the dinosaurs’ extinction.

The study sheds light on the explosive adaptive radiation that gave rise to modern snake diversity. Diet diversification in snakes slowed after the initial radiation, but some lineages experienced further bursts of adaptive evolution. For example, Colubroid snakes diversified when Old World ancestors colonized North and South America. These findings show that mass extinctions and new biogeographic opportunities can spur evolutionary change, the authors say.

“Much of the stunning ecological diversity in snakes seems to result from evolutionary explosions triggered by ecological opportunity,” Grundler adds. “We find a major burst of snake diet diversification after the dinosaur extinction, and we also find that, when snakes arrive in new places, they often undergo similar bursts of dietary diversification.”

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