Ancient Anacondas Maintained Size Despite Warming Temperatures, Study Finds

A novel study published in the Journal of Vertebrate Paleontology reveals that ancient anacondas, despite living during a warmer period in Earth’s history, did not grow to be significantly larger than their modern counterparts. This finding challenges the expectation that warmer temperatures would have led to gigantism in these reptiles.

Unexpected Stability in Anaconda Size

Researchers expected to find evidence of anacondas reaching lengths of seven or eight meters during the Miocene epoch, a period roughly 12 million years ago when global temperatures were higher. However, analysis of fossil remains indicated that the size of anacondas has remained relatively stable since their emergence in tropical South America around 12.4 million years ago.

“This is a surprising result because we expected to find the ancient anacondas were seven or eight metres long,” said Andres Alfonso-Rojas, lead author of the study and a PhD student at the University of Cambridge. “But we don’t have any evidence of a larger snake from the Miocene when global temperatures were warmer. By measuring the fossils, we found that anacondas evolved a large body size shortly after they appeared in tropical South America around 12.4 million years ago, and their size hasn’t changed since.”

Resilience in a Changing World

The study suggests that the anaconda’s ability to maintain its size is linked to its habitat. Anacondas thrive in warm, wet environments like swamps, rivers, and marshes, which support a rich diversity of prey. These conditions are reminiscent of the broader planetary climate during the Miocene epoch.

“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,” Alfonso-Rojas noted.

Potential Threats from Climate Change

While anacondas have proven remarkably resilient, researchers caution that ongoing climate change and habitat loss could pose a threat to their survival. Alterations to their wetland habitats could disrupt the ecosystem and potentially lead to a decline in anaconda populations.