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Fossils reveal anacondas have been giants for over 12 million years
Overview
New fossil evidence from Venezuela sheds light on the long history of giant snakes. A team studying 183 fossilised backbones attributed to anacondas, found in Falcón State, indicates these reptiles reached lengths of four to five metres. This size aligns with the largest living anacondas today, suggesting a sustained pattern of gigantism in the lineage for more than 12 million years. The work is published in the Journal of Vertebrate Paleontology and described by journalist Jacqueline Garget for the journal’s audience.
The research uses a robust dataset: 183 backbones from at least 32 snakes gathered at a single site, complemented by fossil information from additional South American locations. When combined, these data yield a consistent size estimate that places ancient anacondas squarely in the same size category as contemporary individuals. This continuity over geological timescales highlights the stability of ecological roles and body plans within the boid family of snakes in South America.
“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're super-resilient.”
Andrés Alfonso-Rojas, a PhD student and Gates Cambridge Scholar in the Department of Zoology at the University of Cambridge, lead author of the research.
Fossil Evidence and Methods
The core data consist of backbones from multiple specimens recovered from a well-documented site in Falcón State. By counting elements and applying established allometric and comparative methods used in modern boid snakes, researchers translated vertebral measurements into overall body length estimates. Cross-site comparisons with other South American fossil records strengthen the case that ancient anacondas were already comparably large, and that such gigantism persisted across millions of years.
The approach combines direct measurements with broader palaeontological context, allowing the researchers to place the Venezuelan find within a wider temporal framework. The results indicate that the evolutionary history of giant snakes in the Neotropics involved a stable maximum size that mirrors the dimensions seen in extant species today.
Implications for Evolution and Ecology
The findings contribute to a clearer picture of how large predators persisted in tropical ecosystems over extended periods. The persistence of four to five-metre anacondas implies that ecological niches supporting large snakes—such as prey availability and climate stability—were present in the region for many millions of years. This challenges assumptions that giant snakes were a more transitory feature of South American faunas and suggests a long-term ecological equilibrium for boid snakes in the neotropics.
Beyond size alone, the study informs discussions about morphological stasis and the potential drivers of gigantism in snakes. The Venezuelan fossils provide a tangible data point for refining models of snake growth, metabolism, and ecological roles during the Neogene and Pleistocene transitions.
Publication Context
The study appears in the Journal of Vertebrate Paleontology, with findings summarized for a scientific audience by journalist Jacqueline Garget. The work highlights the importance of regional fossil records in painting a broader picture of snake evolution and demonstrates how detailed vertebral analysis can yield insights into body size that resonate with today’s species.
