“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.”
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.