Long-snout trifid fish discovered for the first time in Qujing, Yunnan 410 million years ago

Swimming "Trident": Long-snout trident (right) and Zhaotong trident (left) ecological restoration map (painted by Yang Dinghua)

Photos of the early Devonian Braggian trifid fish fossils in Qujing, Yunnan 410 million years ago (provided by Gai Zhikun)

Recently, the journal "Paleobiodiversity and Paleoenvironment" published online the latest report on the snout of trichodes from the group leader Xujiachong of the Early Devonian Prague in Qujing, Yunnan, which was completed by the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences and others.

The long-snout trifid fish is classified as a jawless armored fish subclass Trifididae.

The discovery has unique biogeographic significance

The Trifididae has always been a mysterious and unique existence among the jawless armored fishes.

Longsnout trichosaurus was originally discovered by Liu Yuhai in 1975 in the Devonian strata of Yanmenba, Longmen Mountain, Jiangyou, Sichuan.

Yunnan Zhaotong and Sichuan Jiangyou are geographically close to each other, and both belong to the northern part of the South China Plate.

However, there are thousands of kilometers of geographical separation between the north and south of the trichondrus.

The first discovery of the long-snout trichosaurus in the "Ancient Fish Kingdom" in Qujing, Yunnan, not only expanded the distribution range of the trichosanthes in the southern China plate, but also the Qujing area was located exactly between the Jiangyou area and the northern part of Vietnam.

The discovery has important morphological, taxonomic and palaeogeographic significance

The discovery of Longsnout Trichuris in Qujing has very important morphological and taxonomic significance.

Therefore, the existence of the two middle horizontal tubes can be regarded as a new common ancestral trait of the trifididae.

In addition, Sanqi fish and Dayong fish, Hanyang fish and Xiushui fish have some other similar characteristics.

The discovery of the long-snout tricuspid fish in Qujing also has very important paleogeographic significance.

About 420 million years ago (Lochkoff period), a transgression occurred in southern China, which extended from southwest to central and western Guangxi.

At this time, the appearance of ancient fish assemblages, early vascular plant assemblages, and invertebrate brachiopods Tokyo Shiyan assemblages showed a high degree of similarity in local colors, which was significantly different from the appearance of fauna in other parts of the world, such as in Australia and North America.

In 1981, Gavin Young, a well-known Australian palaeoichthys scholar, first regarded the ancient fish of the South China plate of the Early Devonian as an independent fauna and named it the "Armorfish-Yunnan fish" fauna.

The discovery has very important biostratigraphic significance

The discovery of Longsnout Trichuris in Qujing also has very important biostratigraphic significance.

In particular, the Vietnamese trichondrus of the Si Ka group in Vietnam, because of its symbiosis with the Liaojiaoshan polygill fish, the French paleontologist Philip Jeanvier has always believed that its appearance is slightly later than the era when the Chinese trichondrus appeared.

However, the paleontological fossil evidence in recent years shows that the Liaojiaoshan Polygillfish has a long continuation period, possibly from the Early Devonian Lochkoffian (about 420 million years ago) to the Early Devonian Braggian (approximately 420 million years ago).
410 million years ago).
The trichondrus is an important member of the Xujiachong assemblage.
The comprehensive comparison of 8 fish-bearing strata in South China and northern Vietnam in the Early Devonian shows that the strata of these non-marine trichonds can be compared with the Lianhua Mountain in the Liujing section of Guangxi.
The transition layer between the Nakaolin Formation and the Nakaolin Formation is contrasted, and the bottom of the Nakaolin contains the Bragg age conodont standardization stone with a clear age.

Therefore, the upper middle and upper parts of the Si Ka Formation in northern Vietnam and the upper part of the Lianhuashan Formation in Guangxi should be in the Prague age, not the Lochkoff age.
The assemblage of ancient fish fossils from the Bragg Age of the South China Plate records in detail the rapid radiative evolution of armored fishes, especially South China Fishes, in the Early Devonian.

This research was funded by the National Natural Science Foundation of China, the Key Research Program of Frontier Science of the Chinese Academy of Sciences, and the Strategic Leading Science and Technology Special Project (Category B) of the Chinese Academy of Sciences.
(Source: China Science News, Cui Xueqin)

Related paper information: https://doi.
org/10.
1007/s12549-021-00486-z