February 4, 2009

Scientists Find Fossil Of World’s Largest Snake

An international team of scientists announced Wednesday the discovery in northern Colombia of fossil remains of the largest snake ever known to have lived.

The scientists named the 2,500 pound, 43 ft. long snake Titanoboa cerrejonensis ("ty-TAN-o-BO-ah sare-ah-HONE-en-siss"), meaning titanic boa from Cerrejon, the open-pit coal mine where the fossils were discovered.

"This thing weighs more than a bison and is longer than a city bus," snake expert Jack Conrad of the American Museum of Natural History told the Associated Press.

The snake, whose body was at least 3 feet wide, is believed to have lived 58 to 60 million years ago, after an asteroid hit near the Yucatan coast of Mexico wiped out dinosaurs and other creatures 65 million years ago.

At the time, the Titanoboa cerrejonensis may have been the largest non-ocean vertebrate on the planet.

"It is a mind-bogglingly big snake," paleontologist Jason Head of the University of Toronto, lead author of a report about the find, told Reuters.

"This thing is a crocodile eater, catching and eating them in the water," Head added.

"It was a bad day for the crocs."

"At its greatest width, the snake would have come up to about your hips," said geologist David Polly of Indiana University, who identified the position of the fossil vertebrae, which made an estimate possible.

"The size is pretty amazing. We went a step further and asked, how warm would the Earth have to be to support a body of this size."

Smithsonian Tropical Research Institute geologist Carlos Jaramillo and University of Florida vertebrate paleontologist Jonathan Bloch discovered the fossils in the Cerrejon Coal Mine in northern Colombia, and investigated what the snake's environment might have been like.

Head made an estimate of the Earth's temperature 58 to 60 million years ago in an area encompassed by modern-day Colombia.

"Scientists have long known of a rough correlation between a period or epoch's temperature and the size of its poikilotherms [cold-blooded creatures]," said Paul Filmer, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which co-funded the research.

"As Earth's temperature increases, so does the upper size limit on poikilotherms."

"The anatomy of a species is correlated with its environment on broad scales," Polly said.

"If we understand these correlations better, we will know more about how climate change affects species, as well as how we can infer things about past climates from species that lived then."

Head estimated that a snake the size of Titanoboa would have required an average annual temperature of 86 to 93 Fahrenheit to survive. By comparison, the average yearly temperature of today's Cartagena, a Colombian coastal city, is about 83 degrees Fahrenheit.

"Tropical ecosystems of South America were surprisingly different 60 million years ago," said Bloch.

"It was a rainforest, like today, but it was even hotter and the cold-blooded reptiles were substantially larger. The result was, among other things, the largest snakes the world has ever seen."

The tropical rainforest at Cerrejon appears to have thrived at a temperature of 32 degrees Celsius, five degrees warmer than the upper temperature limit for tropical rainforests in modern times.

"These data challenge the view that tropical vegetation lives near its climatic optimum, and has profound implications for understanding the effect of current global warming on tropical plants," said Jaramillo.

Evolution has produced a variety of gigantic animals over the last several hundred million years--dinosaurs, ancient dragonflies and today's blue whale, to name a few. Why some species' lineages produce monsters remains a matter of debate among evolutionary biologists and ecologists.

The scientists classify Titanoboa as a boine snake, a type of non-venomous constrictor that includes anacondas and boas.

Polly extrapolated the placement of Titanoboa fossil vertebrae by comparing the fossils' structure to the vertebrae of today's boine snakes.

Snake vertebrae become larger near a snake's midsection, but they are also structured differently than vertebrae closer to a snake's head or tail.

Using a computer model, Polly estimated that the fossil vertebrae originated near Titanoboa's middle. Therefore, the snake could have been even larger than it appears.

The project was co-funded by the Smithsonian Institution, Carbones del Cerrejon LLC (Colombia), Geological Society of America, Florida Museum of Natural History, University of Florida, University of London and Indiana University.

The findings were published in the journal Nature.  Along with Head, Alexander Hastings, Jason Bourque, Fabiany Herrera and Edwin Cadena of the University of Florida contributed to the report.


Image Caption: This artist's rendering of the largest snake on record shows its size. The boa likely spent much of its life in or near water. Credit: Jason Bourque, University of Florida


On the Net: