Andrés Alfonso-Rojas, University of Cambridge on how giant anacondas have survived: “They are super-resilient”

A new study has challenged previous knowledge on anaconda, the giant snakes that haunt people nightmares.

Researchers from the University of Cambridge, led by Andrés Alfonso-Rojas, examined fossilised remains unearthed in Venezuela’s Falcón State to piece together the evolutionary history of the giant South American snake. They measured 183 fossilised vertebrae, representing at least 32 individual snakes, to estimate the body lengths of ancient anacondas living during the Miocene epoch. What they found challenges some long-held assumptions about how reptile size responded to past climate change.

During the Miocene, roughly 12.4 to 5.3 million years ago, global temperatures were higher and wetlands more widespread. Many animal species that thrived in those conditions grew to immense sizes. Giant crocodiles and enormous freshwater turtles, for example, dominated the region’s waterways before eventually disappearing.

“The giant anacondas have survived, they are super-resilient”

“Other species like giant crocodiles and giant turtles have gone extinct since the Miocene, probably due to cooling global temperatures and shrinking habitats, but the giant anacondas have survived, they are super-resilient,” he explained.

Snakes, especially anacondas, seem to have followed a different path. Instead of growing ever larger, these snakes reached their substantial size early in their history and have remained within much the same range ever since.

“This is a surprising result because we expected to find the ancient anacondas were 7 or 8 m long,” he said. “But we don’t have any evidence of a larger snake from the Miocene when global temperatures were warmer.”

Modern green anacondas, members of the Eunectes genus, frequently measure between four to five metres in length, and in rare cases individuals can approach seven metres. The fossil data suggests ancient anacondas were very similar in size to these modern giants. This stability contradicts the expectation that warmer climates in the distant past would have led to even larger individuals, given reptiles’ sensitivity to temperature.

So, the question remains: just why have anacondas held onto their size when other prehistoric giants vanished? It seem that the answer may lie in their habitat and lifestyle. Anacondas favour the warm, wet environments of South American rivers, marshes and swamps, a setting not entirely unlike the expansive Miocene wetlands where their ancestors thrived.

These ecosystems continue to support abundant prey such as capybaras, fish and other mammals, providing the ecological conditions that enable large body size to be advantageous.

Get your game on! Whether you’re into NFL touchdowns, NBA buzzer-beaters, world-class soccer goals, or MLB home runs, our app has it all. Dive into live coverage, expert insights, breaking news, exclusive videos, and more – plus, stay updated on the latest in current affairs and entertainment. Download now for all-access coverage, right at your fingertips – anytime, anywhere.