"We were able to use the snake, if you will, as a giant fossil thermometer," study author Head said.
His team found that, for Titanoboa to reach its epic proportions, mean year-round temperatures would have been about 90 degrees Fahrenheit (32 degrees Celsius)—significantly hotter than today's tropics.
This supports the idea that tropical temperatures spike as the rest of the world heats up due to global warming, the study authors say.
The competing theory is that, during bouts of warming, the tropics stay about the same average temperatures as they are today while areas north and south of the Equator heat up.
James Zachos, an expert on ancient climates at the University of California, Santa Cruz, who was not involved in the study, agreed.
As the biggest known snake, Titanoboa supports the idea of "much hotter tropics during extreme greenhouse periods," Zachos said.
Big Reptiles on the Horizon?
Study co-author Jonathan Bloch is a vertebrate paleontologist at the University of Florida's Museum of Natural History in Gainesville.
The same Colombian coal mine that contained the biggest snake also yielded massive turtles and crocodiles, he said.
"You can think about it as an ecosystem dominated by giants, I think, and these are probably giants that got large because of the warmer mean annual temperature," he said.
The findings, detailed in this week's issue of the journal Nature, paint a picture of what the future might hold if supercharged global warming takes place.
According to some models, global temperatures could approach the same levels that gave rise to the biggest snake by the end of this century.
If current greenhouse gas emissions continue apace, there's a chance snakes the size of Titanoboa could return, Bloch said.
"Or maybe snakes would go extinct in the tropics," he said. "In other words, the warming could happen so rapidly that they wouldn't have time to adapt."
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