By comparing the sizes and shapes of its fossilized vertebrae to those of extant snakes, researchers estimated that the T. cerrejonensis reached a maximum length of 12 to 15 metres (40 to 50 ft), weighed about 1,135 kilograms (2,500 lb), and measured about 1 metre (40 in) in diameter at the thickest part of the body.
The largest eight of the 28 T. cerrejonensis snakes found were between 12 and 15 metres (39 and 49 ft) in length. In comparison, the largest extant snakes are the Python reticulatus, which measures about 9 metres (30 ft) long, and the anaconda, which measures about 7.5 metres (25 ft) long and is considered the heaviest snake on Earth. At the other end of the scale, the smallest extant snake is Leptotyphlops carlae with a length of about 10 centimetres (4 in).
Titanoboa, pronounced , meaning "titanic boa", was a genus of snake that lived approximately 60 to 58 million years ago, in the Paleocene epoch,a 10-million-year period immediately following the dinosaur extinction event. The only known species is the Titanoboa cerrejonensis, the largest snake ever discovered.