Scientists discovered a rock with fossils of a group of fish swimming together in the same direction. The discovery suggests that animals learned to function in groups much sooner than we initially believed.
Erismatopterus Levatus Similar to Today’s Fish
Erismatopterus levatus is an extinct fish species not larger than the size of your thumb, and they moved in groups just like today’s fish. The fossil was found in limestone that dates back to the Eocene Epoch era.
The fossil consists of around 250 small fish, all swimming in one direction. It is difficult to find out what exactly killed the fish in an instant. Although, it could have been something as simple as a collapsing sand dune. This would probably bury them in a split second and help us discover them 50 million years later. Scientists suggest that this group was probably only a small part of a much bigger one that managed to move from the sand dune.
Once they analyzed the position of the fish, the scientists managed to conclude that this ancient fish also functioned under the rule of attraction and repulsion. It means that fish travel together in a group, but they keep their distance from the closest fish near them. Which just might be the reason why the rest of the group escaped.
Nobuaki Mizimoto, a behavioral ecologist from the Arizona State University, says that this collective behavior can be seen in many different species. Insects behave the same, and so do the birds. But the scientists are still lucky to have found this fossil as they never had firm evidence whether ancient, extinct species behaved the same way. This suggests that the group traveling behavior evolved a long time ago.
The limestone originally comes from the Green River, which is a formation stretching over what is today’s Wyoming, Colorado, and Utah. Mizumoto’s field of study mostly focuses on termites and the way they build and function together. However, he was still pleasantly surprised to find this sediment in a Katsuyama Museum, Japan, in 2016.