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A 12-Meter-Long Snake
Carlos Jaramillo spends much of his time digging in the dirt. He is a paleontologist. This means he is a scientist who studies fossils. Fossils are the remains of ancient animals and plants, the traces or impressions of living things from past geologic ages, or the traces of their activities). Like all paleontologists, Jaramillo looks for fossils to tell us about past life on Earth. Fossils can also tell how life and environments on Earth have changed over time.
Jaramillo has spent years in northeastern Colombia, in a region called Cerrejón. Scientists have found many different kinds of plant and animal fossils here. One fossil is from a species of snake that was larger than a school bus. This snake lived about 60-58 million years ago. This snake has been named Titanoboa cerrejonensis. This means “titanic boa from Cerrejón.”
At first glance, Cerrejón might seem like an unusual place to dig for fossils. It is an open-pit coal mine. Energy companies dig into the ground to get coal. They then cart the coal off in huge trucks. The digging by the coal companies has exposed rock layers that hold fossilized remains.
These fossils include a variety of different plants and animals. Remember that using the layers of a rock sample can help scientists figure out the relative age of different rocks and fossils. The bottom layer is generally the oldest layer. The top layer is the most recent layer. Scientists have found a variety of different fossilized life forms here. The fossils tell of an environment very different from the one today.
Evidence of a Changing Planet
Modern-day Cerrejón is an arid, desert-like climate. It receives little rain. However, the fossil evidence shows that the region used to be a tropical rainforest. It was filled with plants and animals that would have thrived in a wet, hot climate. There are fossils of giant turtles weighing up to 136 kilograms (300 pounds). There are also fossils of lungfish that were 2 meters (7 feet) long.
The scientists digging in Cerrejón think there is a reason the fossils were so massive. They believe it is because the climate 60 million years ago was much warmer than it is today. Reptiles like snakes are cold-blooded animals. This means they cannot regulate their body temperature internally. Instead, they rely on their external environment to keep their body temperature within the right range. According to the scientists, a warmer climate would have allowed reptiles to grow much larger. There is still debate about this idea, however. Other scientists disagree with that conclusion.
Comparing Fossils with Modern Life
Finding fossils is like working on a jigsaw puzzle. This is because fossils are almost never found fully intact. Instead, paleontologists find fragments of bone. They might find parts of an animal’s vertebrae. Or they might find ribs or shoulder blades. They then try to piece together a picture of what the animal looked like, how it behaved, and what its environment was like.
One challenge facing the scientists in Cerrejón was determining the size of the ancient snakes. This is because they only found parts of its skeleton. They used a mathematical model of a snake spinal column. This model was based on modern snakes because all snakes share certain characteristics. This model allowed the scientists to predict the ancient snake’s length. They estimated it was between 13 and 15 meters (42 and 49 feet) long.
Fossils and Evolution
The scientists from Cerrejón also wanted to figure out what modern species of snake the ancient Titanoboa was most closely related to. They used the vertebrae of two different fossil snakes they found to try to answer this question.
They began by observing that the fossil bones had a lot in common with those of modern snakes including boa constrictors and anacondas. Both of these species are common in South America today. The scientists observed that the fossil bones were more similar in structure to modern boas. However, the ancient tropical environment would have been more suited to anacondas, which live in the water. They predicted that Titanoboa was more closely related to the modern-day boa because of the structural similarities in the bones.
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