Most four-limbed creatures, including dinosaurs but also humans, were believed to have evolved from fish. Scientists thought this whole process took place at the tropics, but a recent discovery might shift the whole history of tetrapods. Researchers discovered two new fossils in South Africa that turned this whole theory upside down.
The tetrapods were found in an interesting location
Humans, as well as most four-limbed creatures that have ever lived, belong to the group called tetrapods. The general conviction was that, one day, tetrapods moved out from the tropical waters and started walking on land. However, it turns out they don’t actually originate from the tropics.
At Waterloo Farm, an archaeological site in South Africa, researchers found pieces of tetrapod fossils. These were the oldest creatures of the species lying further away from the tropical area. Given their location, researchers concluded they had a different origin. Back when South Africa belonged to the supercontinent Gondwana, the tetrapods might have lived close to Antarctica.
The discovery changes the theory on tetrapod evolution
To find out where fossils used to live, researchers built simulations of how continents had moved over time. This way, they found out South Africa was closer to Antarctica. The area wasn’t an icy one, but it still exhibited polar nights that lasted for six months.
These early tetrapods dated back to the Devonian period. Judging from these findings, researchers could now expand the area occupied by these creatures. They were still present at the tropics and in other regions, but also within the Antarctic circle. This is a remarkable discovery, as it changes the theory on tetrapod evolution.
Since these creatures were more widespread, it’s no longer clear if they evolved at the tropics. As their fossils were more widespread, they could have originated basically anywhere. Then, they could have moved from this unknown location to all the other areas they occupied. Since these two South African fossils were older than other tetrapod remains, there’s a bigger chance of the origin being in Antarctica.
The study was published in the journal Science.
Image source: Wikimedia Commons