New 438-million-year-old fish fossil unveils evolutionary past from Xinjiang to Yangtze River

Chinese scientists recently found a new fish fossil while exploring the ancient layers of Lixi town, Wuning County in Jiujiang city, East China’s Jiangxi Province, a place famous for being a crucial fossil site for ancient vertebrates, said Science and Technology Daily.

The newly found armored fish fossil, named after the Lixi Western Region Fish, was estimated to be around a whopping 438 million years old, as cited by the scientists from the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Science on Friday in the newspaper.

According to the new finding, the fish species lived in the Silurian period (from 443.8 million years ago to 419.2 million years ago), a time when many biologically significant events occurred.

Scientists noted that the discovery holds great significance in deepening the understanding of the evolutionary history and diverse characteristics of armored fish, a distinctive jawless fish exclusive to China and northern Vietnam.

It also provided some clues about their early migration patterns, where scientists believed that the species’ geographical range at that time expanded from the Tarim Basin in Northwest China’s Xinjiang Uygur Autonomous Region to the southern China region where China’s Yangtze River runs through.

Researchers also observed distinctive features in the Lixi Western Region Fish, such as serrated edges on its head armor, setting it apart from the Zhang’s Western Region Fish found in Keping, Xinjiang, as early as in 2007.

“Jiujiang in Jiangxi is a crucial fossil site for ancient vertebrates during the early Silurian period in China. In Wuning County, paleontologists have discovered a diverse animal group, predominantly of which are armored fish species,” Zhang Hui, a Beijing-based archaeologist, told the Global Times on Sunday.

The Lixi Western Region Fish marks the fourth newly identified armored fish species in Jiujiang, following previous discoveries like Junqing Clearwater Fish, Hedgehog Anji Fish, and Jiujiang Jiangxia Fish. The last was just found in May by the same research team in the early Silurian layers of Wuning, Jiujiang.

In May, the team’s investigations revealed findings that the Jiujiang Jiangxia Fish and the previously discovered Houti Jiangxia Fish in Wuhan, Central China’s Hubei Province, belong to one fish genus family, making them long-lost “siblings” separated around 438 million years ago.

That groundbreaking discovery has been published in the Acta Geologica Sinica-English Edition. Lead author Shan Xianren highlighted at the time that systematic paleobiology research is like a “family reunion journey for extinct species,” especially when different species under the same genus are found.