You wouldn’t want to come across this in your backyard

Sixty million years ago a giant boa-like snake weighing more than a ton and stretching 42 feet from head to tail slithered through the rainforests of South America, searching out the crocodiles and turtles that were its prey. Excavations in an open-pit coal mine in Colombia co-organized by Carlos Jaramillo, staff scientist at the Smithsonian Tropical Research Institute in Panama and Jonathan Bloch, curator of vertebrate palaeontology at the University of Florida’s Florida Museum of Natural History, recently exposed the fossil remains of this new snake. Scientists have named it Titanoboa cerrejonensis.

Photo: Fossils from a 60-million-year-old South American snake, whose length and weight might make today’s anacondas seem like garter snakes, have been discovered in Colombia. (Artist’s rendering by Jason Bourque, Florida Museum of Natural History, courtesy of the National Science Foundation)

Titanoboa is the largest snake ever known, and was the largest non-marine vertebrate from the epoch immediately following the extinction of the dinosaurs 65 million years ago. “The discovery of Titanoboa challenges our understanding of past climates and environments, as well as the biological limitations on the evolution of giant snakes,” says Jason Head, a research associate at the Smithsonian’s Natural History Museum and lead author on the paper describing the new snake species. “This shows how much more information about the history of Earth there is to glean from a resource like the reptile fossil record.”

Compare the fossil precloacal vertebra from Titanoboa cerrejonensis at left with that of a modern Boa constrictor. The modern snake was more than 11 feet long.

Surrounded by huge trucks extracting coal from Cerrejon, one of the world’s largest open-pit mines, researchers discovered the fossilized bones of a number of enormous snakes, as well as the fossilized remains of crocodiles and turtles. A wealth of fossilized plant material from the oldest known rainforest in the Americas, which flourished at Cerrejon some 58 to 60 million years ago, also was recovered by the scientists.

Head, who is also professor of ecology and evolutionary biology at the University of Toronto Mississauga, and David Polly, associate professor of geosciences at Indiana University, used the ratio between vertebral size and the length of existing snakes to estimate that Titanoboa must have reached 13 meters (42 feet) and weighed more than a ton.

“Tropical ecosystems of South America were surprisingly different 60 million years ago,” Bloch says. “It was a rainforest, like today, but it was even hotter and the cold-blooded reptiles were substantially larger. The result was, among other things, the largest snakes the world has ever seen.”

Titanoboa’s size indicates that it lived in an environment where the average yearly temperature was 86 to 93 degrees Fahrenheit, say the researchers. This estimate coincides with paleoclimatic models predicting greenhouse conditions. “This temperature estimate is much hotter than modern temperatures in tropical rainforests anywhere in the world,” Jaramillo explains. “The fossil floras that the Smithsonian has been collecting in Cerrejon for many years indicate that the area was a tropical rainforest. That means that tropical rainforests could exist at temperatures 3 to 4 degrees Celsius hotter than modern tropical rainforests experience.”

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