Fossils of 50 million years of the ancient fish herd nearly 300 children

Fish fossils of hundreds of fish were discovered on high mountains in the US, helping the team better understand the behavior of ancient fish.

The researchers found the fossil of an ancient fish colony at the Green River Formation, a hydro-geological system 50 million years ago, storing sediments of the Rocky Mountains' lake cliffs running through the state of Colorado. , Utah, and Wyoming today. The specimen is 57cm long, 37cm wide, contains fossils of at least 259 fish that swim close together and face the same side, indicating they move in flocks.

Fossil specimens of ancient fishes in the Tan Tan.(Photo: IFL Science).

According to a report in the journal Proceedings of the Royal Society B, the University of Arizona team looked closely at the location of the fish in the herd and simulated to estimate how the fish and individual fish moved.The collective behavior of the fish is a balance between sucking and pushing. Each fish has just been pushed out of the nearby swimming pool to avoid hitting each other, and being attracted to swim in line towards the remote ones, so they don't get lost.

Like today's fish, the shape of an ancient fish herd contributes to reducing the risk of being eaten and confused by predators. It seems that fish density is higher in the central region safer, and lower at the edge of the herd, where predators easily attack. It is likely that larvae and immature fish hide in the middle of the herd while healthy adult fish spread out.

Researchers are not sure how the fish structure is preserved as fossils. However, it is found that fish swim in groups by combining a range of behavioral rules at least from Tan Tan.