CLEVELAND — Rocks beneath a coal mine in Colombia have yielded fossils of what could be the world’s largest snake, a relative of today’s boa constrictor that was12.8 meters long and weighed more than a ton.

Few of today’s snakes exceed 9 meters in length, says Jonathan Bloch, a vertebrate paleontologist at the Florida Museum of Natural History at the University of Florida in Gainesville. Some of the snakes that lived about 60 million years ago, however, would have dwarfed their modern kin, he reported Wednesday in Cleveland at the annual meeting of the Society of Vertebrate Paleontology.

At a site in northern Colombia, Bloch and his colleagues unearthed the partial remains of an ancient snake. Each of the dozen or so vertebrae in that body segment measured about 10 centimeters across. That’s about twice the width of the largest vertebra taken from a 6-meter–long, modern-day anaconda, another modern relative, Bloch notes.

None of the ribs included in the fossil are complete, but the size and curvature of the fragments that remain indicate that the snake “would have had trouble fitting though the door into your office,” he adds. The gargantuan fossils represent an as yet unnamed species.

Estimating a snake’s length from fragmentary remains is difficult because most of the creature’s vertebrae differ only in their size, not in their proportions. Bloch and his colleagues can’t readily determine whether the segment that they unearthed came from the thickest portion of the snake, so their estimates of the snake’s size and weight are minimum values. The researchers contend that the ancient snake they discovered would have stretched at least 12.8 meters and weighed at least 1.27 metric tons.

Even one complete vertebra can enable scientists to make good estimates of a snake’s minimum length, says S. Blair Hedges, an evolutionary biologist at Penn State University in University Park. “This [snake] is definitely bigger than any modern-day snake,” he notes. The record length for a living species belongs to a reticulated python that measured 10 meters long.

The rocks that once entombed the snake remains had been laid down as clay-rich sediments on floodplains near a coastline about 60 million years ago, Bloch says. Other fossils excavated from the same layers include an aquatic turtle whose shell was 2 meters across and whose skull was the size of a dinner plate. So far, the paleontologists haven’t unearthed any mammal fossils at the site, so it’s a mystery as to what these creatures preyed upon.

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