The authors of the new study looked at 183 fossilized anaconda vertebrae, thought to account for around 32 individual snakes. They then used this data to figure out how long the anacondas would\u2019ve been when they were still alive.<\/p>\n
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An example of the fossil anaconda vertebrae measured in the study.<\/p>\n
Image credit: Jason Head<\/p>\n
As the heaviest extant snake on Earth<\/a>, anacondas are big today, so it was expected that Miocene-era anacondas would\u2019ve been even larger, but the fossil bones revealed they were around 5.3 meters (17 feet) long, which is about the same size as anacondas today.\u00a0<\/p>\n “This is a surprising result because we expected to find the ancient anacondas were seven or eight metres long,” said lead author Andr\u00e9s Alfonso-Rojas, a PhD student and Gates Cambridge Scholar in the Department of Zoology at the University of Cambridge, in a statement<\/a>. “But we don\u2019t have any evidence of a larger snake from the Miocene when global temperatures were warmer.”<\/p>\n “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\u2019t changed since.”<\/p>\n That they\u2019ve maintained their gigantism for so long may come down to anacondas\u2019 chosen habitat. Today, they live in swamps, marshes, and rivers in warm and wet areas. We know they were more common in the Miocene, but across the Amazonian region, there remains enough water, warmth, and food to keep them huge.<\/p>\n Most anacondas (of which there are several species<\/a>) are around 4 to 5 meters (13.1 to 16.4 feet) long, but there have been some record-breaking specimens closer to the 7-meter (22.9-foot) mark. Titanoboa<\/a> still trumps anaconda in terms of being the largest snake ever to have lived, but anacondas\u2019 resilience has kept them super-sized for millions of years.<\/p>\n “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,” said Alfonso-Rojas. “They are super-resilient.”<\/p>\n