Titanoboa

Titanoboa, 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.

Size
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),[4] weighed about 1,135 kilograms (2,500 lb),[1] and measured about 1 metre (40 in) in diameter at the thickest part of the body.

Location
In 2009, the fossils of 28 individual T. cerrejonensis were announced to have been found in the coal mines of Cerrejón, La Guajira, Colombia. Prior to this discovery, few fossils of Paleocene-epoch vertebrates had been found in ancient tropical environments of South America. The snake was discovered on an expedition by a team of international scientists led by Jonathan Bloch, a University of Florida vertebrate paleontologist, and Carlos Jaramillo, a paleobotanist from the Smithsonian Tropical Research Institute in Panama.