Fossils from 50 million years ago show the last moments of a group of young fish.

This 50-million-year-old fossil collected by the Japan Museum shows 259 fish swimming in a group, which is one of the earliest known examples of coordinating group behavior. (MiuMuto et al./Journal of the Royal Society B) "KDSPS" One fish, two fish, dead fish and cold fish. "KDSP" and "KDSP" have different spaces in the newly described fossils. About 259 years ago, a school showed 50 million small fish swimming together. According to the author of a new study published in the Journal of the Royal Society B on Wednesday (May 29th), this kind of prefish may be the earliest fossil evidence of known prehistoric fish quick march. Just like today's modern fish, a research team in Arizona came across this extraordinary rock while visiting the Dashi Fossil Exhibition Hall of the Rice Field Memorial in Japan. The researchers cooperated with the museum to determine that this fish fossil may have originated from the American Green River stratum, which is a geological stratum in Colorado today. Wyoming and Utah have many fossils from 53 million to 48 million years ago.

This fish belongs to the extinct Aries. The researchers wrote that they were apparently buried together in a routine swimming, which may be interrupted by a sand avalanche under the water. Except for two tiny samples, all the other samples swam in the same direction in close formation.

In order to prove that this fish really swam in a school of fish, and not just turned into fossils by coincidence, the researchers also conducted a series of simulations to reproduce the possible movements of this group of fish. The simulation results show that these fish obviously not only swim together, but also swim according to a set of eternal behavior rules, which still exist today.

The researchers wrote in the research report: We found traces of two social rules similar to existing fish: rejecting intimate individuals and attracting neighbors. In other words, individual fish swim very close, but not close enough to bump into each other.

According to the author, the body of this ancient swimmer shows that fish (and possibly other animals) evolved coordinated group behavior at least 50 million years ago. This kind of synchronized swimming seems to have succeeded in preventing fish from being eaten by carnivores, even though it can't prevent them from becoming museum exhibits.

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