Home > News content

Discovery of the Cambrian "Fossil Treasure" by Chinese Scientists in the Qingjiang Biota

via:CnBeta     time:2019/4/15 13:07:35     readed:161

Zhang Xingliang and Fu Dongjing, the early life and environment innovation research teams of Northwestern University, China, for the first time, published the 588 million-year-old Cambrian-specific burial soft body fossils discovered in the Changyang area of ​​Yichang, Hubei Province, the “Qingjiang Biota”.

In the introduction to the media, Science magazine said, "The new treasure that reveals the secret of the Cambrian is unearthed."

The British "Nature" magazine said in the report: "The Qingjiang biota has opened another window to observe the spectacular Cambrian, and various new biological groups have never been seen before."

In 2014, the teachers and students of the Department of Geology of Northwest University conducted the “Qingjiang Biota” fossil excavation in Danshui River, Yichang City, Hubei Province. Xinhua News Agency (Photo courtesy of Northwest University)

What kind of "new treasure" has this breakthrough discovery that triggered the evaluation of the praise of the international scientific community? How did Chinese scientists open and explore this treasure?

In 2018, the teachers and students of the Department of Geology of Northwest University conducted the “Qingjiang Biota” fossil excavation in Danshui River, Yichang City, Hubei Province. Xinhua News Agency (Photo courtesy of Northwest University)

518 million years and 12 years: the Cambrian "fossil treasure house" gradually revealed

In the summer of 2007, Zhang Xingliang, a professor of geology at Northwestern University, took several graduate students, such as Fu Dongjing, to conduct field surveys in Changyang, Yichang, Hubei.

Here, surrounded by mountains, the Qingjiang River flows quietly in the mountains. One evening, as they walked along the river, a stone caught the attention of Zhang Xingliang. So they took out the geological hammer and began to knock it up. I didn't expect to find a half-worm fossil with a long thumb in the stone. This "shrimp"-like arthropod is a representative Lin Qiaoli of the Burgis shale fossil reservoir. Then, in this position, they found the invertebrate Narrowworm fossils of the early Cambrian.

Despite being a major discovery, scientists working on early life studies seem to be particularly calm, and it seems that fossils with hundreds of millions of years of history do not seem to cheer them. After studying the fossils of the Lin Qiao Lie fossils, which contained more than 500 million years of life information, their research in this area lasted for 12 years.

Students from the Department of Geology of Northwestern University observed the fossils in the Qingjiang Biota with a microscope (photo taken on April 8). Xinhua News Agency reporter Liu Weishe

It is found that the Changjiang Changyang, a group of Qingjiang biota, is located in the mountainous area of ​​southwestern Hubei, and the Cambrian strata are widely distributed. After 2007, the researchers of the Early Life and Environmental Innovation Research Team of Northwestern University gradually unveiled the mysterious veil of the Cambrian “fossil treasure house” after not knowing how many field excavations and extensive research work.

“At the beginning of the year, I went to Qingjiang two or three times a year. As soon as I heard that the water level was falling and the riverbed was exposed, we went to mine fossils, no matter how windy or rainy, even if it snowed,” recalls the first author of the paper, Professor Fu Dongjing.

The process of collecting fossils is extremely difficult. Workers use the crowbar to pull out the 1 cubic meter-sized stone. The scientific researcher uses a geological hammer to squat along the shale level, while looking at it until he finds the fossil, then sorts, numbers, packs... The fossils came out of the mountains and brought them back to the laboratory.

In the laboratory, each specimen is pre-repaired under a microscope, using scanning electron microscopy to reveal the ultrastructure and elemental composition of fossils, and then to perform high-precision three-dimensional scanning of fossils...

In this way, they searched for “Shihai” in Dashan, Hubei, and found more than 20,000 fossil specimens.

Students from the Department of Geology of Northwestern University are looking for fossils of the Qingjiang Biota (photo taken on April 8). Xinhua News Agency reporter Liu Weishe

The breakthrough in scientific research is an important progress made in 2014. At that time, the team had already collected tens of thousands of fossils. After numerous analyses, comparisons, and studies, the team finally made this judgment: This is an important fossil treasure that can reveal the diversity of animal species and its evolution during the Cambrian explosion.

Speaking of the naming of the Qingjiang Biota, Fu Dongjing said that on the one hand, the fossil burial site is at the intersection of the Qingjiang River and the Danshui River. “One of the more important reasons is that the Qingjiang biota and the Yunnan Chengjiang biota will become the world-famous “China Liangjiang Biota” in the future.”

90% vs. 1%: Scientists' exploration of the "Cambrian life explosion"

The "Cambrian life explosion" is called a "suspended case" in paleontology and geology.

In the Early Cambrian 540 million years ago, the largest and most influential bio-innovation event occurred in the history of Earth's life evolution. More than 90% of the animal species were created in less than 1% of the life history of the Earth. The Cambrian strata suddenly appeared in a large number of invertebrates and the oldest vertebrates - "the world's first fish" Kunming fisheye fossils. However, in the more ancient strata, the obvious ancestral fossils have not been found for a long time. This phenomenon is called the “Cambrian life explosion”, which is called the Cambrian explosion.

How do you explain that so many animal species suddenly emerged in such a short period of time? Has been plagued by the academic community. As a result, the Cambrian explosion was listed as “six natural science problems” along with the origin of life and the origin of intelligence.

"To break the mystery of the Cambrian explosion, we need to find reliable fossil evidence. The Burgess shale fossil library is the best window to explore the Cambrian explosion." Fu Dongjing said.

Students from the Department of Geology of Northwestern University observed the fossils in the Qingjiang Biota (photo taken on April 8). Xinhua News Agency reporter Liu Weishe

The Burgess shale fossil library was first discovered in 1909 in the Burkins shale in the mid-Cambrian period of the Canadian Rockies and was therefore named. Over the past 100 years, more than 50 such fossil banks have been discovered all over the world. Among them, the Burkins shale biota in Canada and the Chengjiang biota in Yunnan, which was discovered in 1984, are the most famous and become “ideal top research destinations”.

“The Qingjiang Biota is the top-level Burgess shale fossil reservoir. Subsequent excavation, research and protection will likely provide a multi-faceted scientific basis for exploring the major scientific problems of the Cambrian explosion.” Fu Dongjing said.

According to reports, after preliminary research on 4351 pieces of a large number of precious fossil specimens collected by Qingjiang Biota, 109 genera have been classified and identified, of which 53% are new species that have never been recorded before. Moreover, there are many soft body organisms in the Qingjiang biota, and 85% of the metazoan genus found have no mineralized bones, and most of them are “basic animals” such as jellyfish and sea anemones without bones.

What is even more surprising to scientists is that the fossil form of the Qingjiang biota has a high fidelity, and all kinds of animals are preserved vividly. The morphological structure of the soft tissues and organs of the eyes, nerves and internal organs of the animals is clearly visible.

The “sparseness curve” analysis of biostatistics shows that the species diversity of the Qingjiang biota will be expected to exceed all known Cambrian soft somatic fossil banks.

New species fossils found in the Qingjiang Biota. Xinhua News Agency (Photo courtesy of Northwest University)

"The characteristics and advantages of the Qingjiang biota are mainly reflected in the highest proportion of new genera, the largest relative diversity of metazoan, the largest group of soft body organisms, the best fidelity of fossil morphology, and the best preservation of primary organic matter, which is difficult to estimate. Research potential." Fu Dongjing said.

Known and unknown: "Three Curtains Cambrian Explosion Hypothesis" and more mysteries

In recent years, the research team of the Early Life and Environment Innovation of Northwestern University, under the leadership of the Chinese Academy of Sciences Shu Degan, has carried out long-term exploration of the Chengjiang biota and the Cambrian explosion, and has achieved systematic innovation.

Based on Darwin's conjecture of "tree evolution" proposed by Darwin, through decades of research and empirical evidence, the "three-scene Cambrian explosion hypothesis" was proposed, which outlines the Cambrian life explosion. In the three stages, the basic outlines of the “animal trees” of the three major branches of the basic animal, the original mouth animal and the rear mouth animal were sequentially created, and the complete early animal lineage tree frame map was constructed for the first time.

"With the development and deepening of future research work, the Qingjiang biota will be the fork of the 'early animal lineage tree', where to open branches and leaves, to find more direct evidence of biological evolution." Academician Shu Deqian said.

Branched algae fossils found in the Qingjiang Biota. Xinhua News Agency (Photo courtesy of Northwest University)

The Qingjiang Biota is 1050 kilometers away from the Chengjiang Biomass Fossil Origin. “Biostratigraphic studies show that the Qingjiang biota and the Chengjiang biota are contemporaries and biotas located in different ancient geographical locations. Both are about 518 million years old, in the era of Cambrian life. The heyday of the emergence of the two. The scientific research value of the two has a strong complementarity," said Zhang Xingliang, the author of the paper.

Compared with the Chengjiang biota, the Qingjiang biota live in a deeper water environment far from the coast, representing a new biome in different ecological environments. “This can be confirmed by more than half of its new genus. Therefore, the large-scale excavation of the Qingjiang biota will provide first-hand materials for discovering and exploring new body configurations and new animal species.” Zhang Xingliang said .

What makes Chinese scientists feel "lucky" is that the world's two most fidelity Burkins shale fossil reservoirs - Burgess and Chengjiang - have experienced high temperature metamorphism and weathering, respectively, after burial. Geological transformation, its samples have been unable to be used for in-depth burial studies. The soft body fossils found in the Qingjiang biota miraculously preserve the original organic matter in the form of a primary carbonaceous film.

Therefore, not only in the field of paleontology research, the discovery of the Qingjiang biota, but also for the evolutionary biology, phylogenetics and burial, paleoecology, geochemistry and other cross-disciplinary research directions, has a very special value.

“The Qingjiang Biota will provide ideal materials for conducting burial and geochemical research, and then carrying out in-depth research on paleoenvironment. The problem of special burial mechanism of animal software structures that has plagued the academic community for many years may be solved in the Qingjiang biota.” Zhang Xingliang said .

It can be expected that with the advancement of interdisciplinary research, China's Qingjiang biota will bring us more: germinating more problems, cracking more mysteries...

Students from the Department of Geology of Northwestern University are looking for fossils of the Qingjiang Biota (photo taken on April 8). Xinhua News Agency reporter Liu Weishe

Students from the Department of Geology of Northwestern University observed the fossils in the Qingjiang Biota with a microscope (photo taken on April 8). Xinhua News Agency reporter Liu Weishe

Students from the Department of Geology of Northwestern University observed the fossils in the Qingjiang Biota with a microscope (photo taken on April 8). Xinhua News Agency reporter Liu Weishe

New species fossils found in the Qingjiang Biota. Xinhua News Agency (Photo courtesy of Northwest University)

New species fossils found in the Qingjiang Biota. Xinhua News Agency (Photo courtesy of Northwest University)

Fossils of leaf foot animals found in the Qingjiang Biota. Xinhua News Agency (Photo courtesy of Northwest University)

Linqiaoli fossils found in the Qingjiang Biota. Xinhua News Agency (Photo courtesy of Northwest University)

Jellyfish fossils found in the Qingjiang Biota. Xinhua News Agency (Photo courtesy of Northwest University)

Cambrian underwater paleontology restoration map. Xinhua News Agency (Photo courtesy of Northwest University)

China IT News APP

Download China IT News APP

Please rate this news

The average score will be displayed after you score.

Post comment

Do not see clearly? Click for a new code.

User comments