As a paleontologist who works in the Southeastern United States, I have spent a great deal of time in the outdoors, and heard some truly amazing and amusing tales regarding snakes. I once had a park attendant try to convince me to sleep on top of a cement picnic table in a campground in central Alabama so the snakes couldn't "get me." Failing that, if I insisted in sleeping on the ground, he asked if I would please coil a rope in a big circle around me because snakes will not crawl over a rope. Of course, he was also concerned that if the snakes didn't eat me, the armadillos would come bite me in the middle of the night (having, what? not been able to find enough ants to eat?). I didn't loose too much sleep worrying about either the snakes or the armadillos. Other examples of snake myths include tales of the "Death Adder" that has a sting in its tail. This snake is sometimes confused with the Hoop Snake, an animal that can outrun a human by putting its own tail in its mouth and rolling like a wheel. Some variations include that Hoop Snakes once they catch you uncoil and sting you with their stinger, but informed people know these are really two completely different snakes. Then there are Milk Snakes, so called because they milk cows, the Mug-whomp Snake with its ring of fur encircling the neck, and the real life Hognose Snake (which eats toads and is completely non-venomous) that poison people with their breath. I've also been told with great veracity that the brownish foam you see sometimes floating down a stream after a rain (the result of organic compounds leached out of forest leaf litter by the rain) is "snake spit." That's a lot of spit. I don't think I want to know what they're doing to produce that much spit. Eew.
And then of course there are the impossibly large snakes always seen by the friend of a cousin's neighbor's uncle. So the other day when I heard the one about the snake that was longer than a school bus and ate crocodiles, I was understandably skeptical. Except that it's true. No, really.
Scientists have recently reported that bones of a fossil snake found in South America scale to an animal in the 42-45 foot range. Aptly named Titanoboa this animal is not just the largest snake ever discovered, it is the longest land/freshwater animal known since the extinctions 65 million years ago that took out the dinosaurs (the K/T boundary extinctions). Although, as the name suggests, it is most closely related to the modern Boa, as in Boa constrictor, due to the type of deposits it was found in it is thought to be a closer analog to the Anaconda (Eunectes). So, it appears to have lived near/in freshwater, and ate,... crocodiles? I use the term "crocodiles" here in the vernacular sense to include members of the Crocodyliformes - crocodiles, alligators, caimans, etc.
No! What? Well, I suppose a 45-foot long, 1.2 ton snake can eat whatever it wants, but before we explore that possibility let's take a step back for a moment to put this in perspective.
Sixty-five million years ago, the course of life on Earth was irrevocably side-swiped by the hammer blow of a 6 mile diameter asteroid slamming into the planet at something like 55,000 miles/hour (more or less, depending on what set of calculations are used). The energy released by this event was perhaps 1,000 times more than every nuclear weapon on Earth going off simultaneously. The resulting extinctions not only left no terrestrial animal weighing more than 50 pounds, but also hit the top of the food chain - the top predators and top herbivores - hardest. With dinosaurs gone, the newly vacant niches were filled by the survivors, and what specific type of animal ended up in those roles depended on what was available on each continent. Mammals at the time were generally small and not yet specialized into the modern groups we know today, so it took awhile for any of them to evolve into the large top predators niche.
In Europe and North America the large top predator that won out early was a bird, the 7 foot tall Diatryma (Gastornis). North and South America became isolated from one another shortly after the K/T extinctions, before the development of the placental mammal groups that gave rise to the predators we know today, such as wolves, lions, and bears. These groups developed in North America and Asia, but not until much later, when the marsupial or pouched animals like opossums branched into the role did South America get predatory mammals (yes, predatory opossums - a topic perhaps for a different blog). In South America, it appears, a giant snake became the top predator, at least in freshwater environments. With mosasaurs, the T. rexes of the oceans, gone marine snakes evolved to lengths of at least 2o feet and existed in south Alabama alongside early whales, such as Basilosaurus, the State Fossil.
Back to diet. A 45-foot, 1.2 ton snake requires a commensurate sized prey. Verifiable, documented accounts of modern Python and Anaconda indicate that their maximum size is 29.7 and 23 feet respectively. These are maximum-recorded sizes, but in the real world one almost never sees examples that large. Surveys involving a thousand or more snakes in the wild fail to turn up snakes longer than 20 feet, and yet modern Anaconda can still eat animals as large as tapirs. So did Titanoboa eat giant tapirs? Well no, since there weren't any yet. The authors of the Titanoboa paper conclude they ate crocodiles. This sounds crazy, but extant anaconda and python do occasionally eat crocodilians, and crocs also eat them. If you Google search this topic you'll find multiple videos of big snakes eating crocodiles but almost nothing for the reverse, although the only serious study I could locate documented only instances of crocodiles eating snakes. I imagine videos of big snakes eating a caiman are more interesting to most people than the reverse.
South American crocodilians of the time belong to the sebecosuchids, vertically deep skulled, long-legged animals with serrate blade-shaped teeth more like the predatory dinosaurs they partly replaced than those of extant crocs. Sebecosuchids in general may have been more terrestrial and less aquatic in their habitat preference than modern crocodilians, which might explain how they divided up the top predator niche with Titanoboa. It seems difficult to believe that Titanoboa ate only or maybe even preferentially crocs, because there are always fewer predators than herbivores, so finding a meal of top predator becomes more difficult. There are also some large lungfish known from the deposits where Titanoboa was found, and recently hints that there might also be some large herbivorous mammals as well. During the time period when Titanoboa is known to have lived, some large (1400 lbs) mammals had evolved in North America, and recently members of this group have been found in South America. Because of the spottiness of the fossil record we may just have not found any large South American mammals yet. So it may be that the discovery of a truly giant snake means that future fieldwork will turn up a previously unknown history of large mammals that formed part of their prey base. We may find that mammals got large earlier than we thought. We may also find more material of Titanoboa. Details of the skull would help solve the riddle of what it ate and inform about the animal's lifestyle.
And we might also find it had a ring of fur around its neck and a stinger on its tail.
NOTE: For everyone with giant snake stories, please see below. The Wildlife Conservation Society has, since the early 20th century, offered a cash reward (currently worth US$50,000) for live delivery of any snake of 30 feet (9.1 m) or more in length. This prize has never been claimed.
James Lamb is a native Birminghamster with a nearly life-long interest in fossils. He collected his first fossil when he was 5 years old. Friends and family members assure him he has not matured much since then. James is curator of paleontology at McWane Science Center, and would like to one day see the absolute treasure trove of Alabama's fossil heritage revealed to the public. When not at work he wishes he were in the field digging up fossils. At home he enjoys reading, jogging, woodworking, and carving. He has been informed that he is in the habit of telling atrocious puns, but this comes as a surprise to him. James describes himself as a "science nerd".