Chinese scientists recently found a shark tooth fossil of the Late Triassic period dating from 220 million years ago in a scientific expedition of Mount Cho Oyu, the world's sixth-highest peak, on the Qinghai-Xizang Plateau, filling in missing information about marine ecosystems during this period.

The scientific expedition, launched in late September this year, aims to better understand the ecology of the high-altitude region and help achieve its sustainable development. More than 120 scientists work in teams to conduct research on water, ecology and human activities around the mountain.

During the expedition, other fossils were also found by a team composed of the Institute of Vertebrate Paleontology and Paleoanthropology under the Chinese Academy of Sciences and the Xishuangbanna Tropical Botanical Garden.

The discovery of a heteromorphic ammonite fossil from the end of the Cretaceous period, 70 million years ago, indicates that some organisms were genetically disturbed before the fifth mass extinction. Ammonites are extinct marine mollusc animals and lived during the periods of history known as the Jurassic and Cretaceous periods. They are excellent index fossils, and linking the rock layer in which a particular species or genus is found to specific geologic time periods is often possible.

The team also found berberis, cotoneaster, spruce and other plant fossils from the early Pliocene period, five million years ago, at altitudes of more than 4,800 meters.

The 2023 Mount Cho Oyu research mission is part of the second comprehensive scientific expedition on the Qinghai-Xizang Plateau initiated in 2017. In 2022 and 2023, Chinese scientists carried out Mount Qomolangma expeditions for two consecutive years.

Similar to the Mount Qomolangma missions, the Mount Cho Oyu expedition is an interdisciplinary comprehensive scientific research effort at extremely high altitudes.

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