The Argentine flag makes us think: What is Paleocuador?

Something strange happened to me: while I was reading an article in an important Argentine scientific publication, I came across a concept that I was not familiar with, even though it was not the main topic of the research. This is the ancient equator, a term that caught my attention and prompted me to investigate further. In this note, I share with you what I discovered.

This month, Argentine science once again captured global attention with a discovery that landed on the cover of the prestigious scientific journal Nature. The fossil discovery allowed scientists to suggest that life on Earth may have emerged from aquatic environments much earlier and in cooler climates than previously thought. Although this study has generated a lot of buzz and much has already been said about it, today I want to focus on an interesting concept that reading this post has led me to learn about: the ancient equator.

In 2024, if we find a fossil in Canada, our first reaction will be to assume that the organism lives in a cold climate. After all, when we think of Canada, we think of snow-covered landscapes and animals adapted to sub-zero temperatures. However, the reality is more complicated than it seems: millions of years ago, the geography of the planet was radically different from what it is today. In fact, the fossil discovered in the far north of Canada could belong to a species that lived in a warm, tropical region. How is this possible?

First, it's important to remember that areas closer to the Earth's equator tend to have warmer climates, while areas farther north and south have cooler climates. This is because, on average, the sun's heat reaches the equator more directly than it does the poles.

Now, about 300 million years ago, the distribution of continents was not as it is today. All of the current continents were united into a supercontinent called Pangaea. Over time, this supercontinent began to break apart, and its parts shifted towards the positions they occupy now, a process known as continental drift, driven by the movement of tectonic plates.

Before and during this slow migration, today's cold, northern Canada was very close to the equator. This means that millions of years ago, what is now Canada was much farther south than its current location, perhaps in a subtropical or even tropical climate. Thus, the species that lived in that region were adapted to warm, not cold, environments.

The concept of paleoequator specifically refers to the ancient equator of the Earth at different times in its geological history. As the continents moved, the location of this line changed. The area near the poles today would have been near the equator in the past, and had a tropical climate, and vice versa.

This phenomenon explains why fossils of tropical plants and animals are found in places that are now cold.

A recent discovery by Argentine scientists provides an excellent example of how the concept of the ancient equator is changing our understanding of Earth’s climate history. The fossil they discovered, which earned them the cover of Nature, was found in Namibia, an African country that today lies near the equator. But dating of the fossil found there showed that when the organism lived, Namibia was much further south, meaning the climate in that region was much cooler than it is today.

This discovery challenged the concept of a biological system (water release by vertebrates), but it challenged me personally in the physical system, and showed me that the climate history of our planet is more dynamic and complex than we could have imagined.