Evolution: Snake diversity increased following Cretaceous-Paleogene mass extinction

The Cretaceous-Paleogene mass extinction event 66 million years ago may have facilitated a rapid increase in the diversity of snake species, suggests a study published in Nature Communications.

Although the Cretaceous-Paleogene mass extinction event led to the loss of an estimated 76% of species on Earth, the diversity of species within some vertebrate groups increased afterwards. However, the impact of the event on snake evolution has been unclear.

Nicholas Longrich, Catherine Klein and colleagues reconstructed the evolutionary history of snakes by combining data on the evolutionary relationships between 115 non-extinct snake groups, the rate of mutation occurrence within DNA, and the geographical distribution of fossilized and non-extinct snakes. The authors found that as few as six snake lineages survived the mass extinction event and that the diversity of snake species increased around the time of the event. Additionally, the range of snake body shapes and sizes was found to have increased after the mass extinction event, and included the evolution of the giant snakes Gigantophis and Titanoboa. The authors indicate that around the time of the mass extinction event, the snake group containing boas and vipers originated in Asia, and groups containing today’s false coral snakes, thread snakes and blind snakes also evolved.

The authors conclude that the ability of snakes to feed infrequently, and the extinction of competitors and predators after the mass extinction event, may have allowed snakes to survive and subsequently diversify.