Studies have found that grass carp may originate in western China and was once widely distributed

Beijing, November 2 (Xinhua) -- A reporter learned from the Chinese Academy of Sciences on the 1st that through the study of about 3,000 grass carp and grass carp pharyngeal tooth fossils, researchers have found that grass carp may have originated in the early Oligocene in western China, and its distribution range was once wider than it is now. The results have been published as cover articles in the academic journal Science in China: Earth Sciences.

Grass carp is one of the "four big fishes" in China, mainly distributed in the big rivers in the east of China, including the middle and lower reaches of the Yellow River, the middle and lower reaches of the Yangtze River, the Huai River and the Hai River Basin. Grass carp uses comb-shaped pharyngeal teeth to feed on large plants in the water, and is currently the only carp in the world with comb-shaped pharyngeal teeth, and the pharyngeal teeth buried by the formation after wear and tear are also valuable materials for scientists to study the evolution of grass carp.

Su Ruifeng, an associate researcher at the Beijing Institute of Life Sciences of the Chinese Academy of Sciences, introduced that this study analyzed the fossil pharyngeal teeth of grass carp and grass carp excavated from 22 fossil sites in China and found that comb pharyngeal teeth with ridges and grooves before and after the crown of teeth have appeared in the early Oligocene about 33 million years ago. "Based on the fossils of pharyngeal teeth unearthed in Inner Mongolia, we have newly established an extinct genus species, Sansheng Gongde-made fish, which is the earliest grass carp found so far, and may be the carnivorous ancestor of grass carp."

Studies speculate that grass carp originated from a carnivorous fish in western China in the early Oligocene, where the temperate grassland environment was different from the habitat of grass carp today. Between about 33 million and 9 million years ago, grass carp spread eastward and migrated, and their distribution range spread throughout the western, eastern and northern parts of China. Around 5 million to 2.5 million years ago, with the strengthening of the uplift of the Qinghai-Tibet Plateau, large rivers flowing eastward into the Pacific Ocean in East Asia formed, and under the influence of the strengthening of Asian summer winds, grass carp gradually evolved into a living species and formed its current distribution range and reproductive habits.

This study also answers an interesting question: There are grass carp distribution in the Heilongjiang and Yellow River systems in China, why is there no record of grass carp in the Liaohe River system between the two major rivers? The researchers speculate that grass carp were probably also distributed in the Liao River, when the Nen River was still upstream of the Liao River. However, since the Quaternary Period, as the upper reaches of the Gunen-Liao River basin have been raided by the Songhua River, a large tributary of the Heilongjiang River, many fish, including grass carp, have been brought to the heilongjiang River in the north, and the amount and length of the Liao River can no longer meet the survival and reproduction of grass carp.

The research was jointly completed by the Beijing Institute of Life Sciences of the Chinese Academy of Sciences, the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and the Guangxi Museum of Natural History.

Source: Xinhua Net