"The largest known snake to have ever existed, Titanoboa cerrejonensis in the Paleocene rainforest. Also featuring a bothremydid turtle Puentemysmushaisaensis with the 1,5 m shell. Both were found from the Cerrejón coal mine, Colombia.”
Phylum : Chordata Class : Reptilia Order : Testudines Suborder : Pleurodira Family : Bothermydidae Genus : Puentemys Species : P. mushaisaensis
Late Paleocene (60 Ma)
2,3 m long and 1 800 kg
Every week, it seems, paleontologists discover a new plus-sized reptile that prowled the warm, wet swamps of middle Paleocene South America. The latest entry (hot on the heels of the even bigger Carbonemys) is Puentemys, a prehistoric turtle that was distinguished not only by its enormous size, but by its unusually large, round shell. Like Carbonemys, Puentemys shared its habitat with the biggest prehistoric snake yet identified, the 50-foot-long Titanoboa. (Oddly enough, all of these one- and two-ton reptiles thrived only five million years after the dinosaurs went extinct, a good argument that size alone was not the cause of the dinosaurs’ demise).
Why did Puentemys possess such a geometrically perfect shell? The most likely theory is that, being cold-blooded, Puentemys needed to fuel its ectothermic metabolism via exposure to sunshine—and a round shell was the most efficient way both to harvest light during the day, and to dissipate excess heat at night. It also didn’t hurt that Puentemys’ enormous shell would have been a difficult pill for any prehistoric snakes, birds or crocodiles to swallow, thus sparing full-grown individuals of this genus from predation.