Group photo of representatives of the research team of the Institute of Paleo-Spine, Chinese Academy of Sciences, Associate Researcher Zhu You'an, Researcher Gai Zhikun, Academician Zhu Min, and Researcher Lu Jing (from left to right).

Photo by China News Agency reporter Sun Zifa

  China News Service, Beijing, September 29 (Reporter Sun Zifa) Including humans, 99.8% of the existing vertebrates on the earth have jaws (upper jaw and jaw), which are collectively referred to as jawed vertebrates or jaws.

The emergence and rise of jaws is one of the most critical leaps in the evolution history of vertebrates from fish to man. Many important organs and body configurations of humans can be traced back to the beginning of the evolution of jaws.

Artistic reconstruction of five newly discovered fishes from the early Silurian period in China.

Zhang Heming's drawing

Why is there a huge gap in the evolution of "from fish to man"?

  When, where, and how did this most critical jumping link take place?

It has been shrouded in fog due to the lack of fossil evidence.

Previously, jaws did not have a relatively complete fossil record until the late Silurian period (about 444 million to 419 million years ago), about 425 million years ago, and the molecular clock inferred that the origin of jaws was no later than 450 million years. In the late Ordovician period (about 485 million to 444 million years ago), there was a huge gap in its early evolution that lasted about 30 million years and spanned the entire Silurian period. It is also known as "from man to fish". "A "ghost branch" of evolutionary probing.

  The team of Academician Zhu Min from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (Institute of Paleoanthropology, Chinese Academy of Sciences) "honed a sword in ten years", and conducted research on five species first discovered in the strata of the early Silurian period in Chongqing, Guizhou and other places about 440 million years ago. Detailed analysis and in-depth research on ancient fish fossils have pushed forward the earliest fossil evidence of jaw teeth and the complete jaw fossil record by 14 million and 11 million years, respectively, thus filling in the global record of jaw fossils in the early Silurian period. It is an important gap, and for the first time provides definite evidence for the rise of jaws and the earliest radiation differentiation.

  A set of four papers, a major breakthrough in the source exploration research of "from fish to man" completed by Chinese scientists, was published in the internationally renowned academic journal "Nature" on the night of September 28th, Beijing time, and was published on the cover of the world on the 29th. The article form is published concurrently.

Academician Zhu Min interprets the latest research results of "from fish to man".

Photo by China News Agency reporter Sun Zifa

What are the important discoveries in the study of 5 ancient fish fossils?

  Academician Zhu Min said in an interview on the eve of the paper's publication that in the past ten years, he led his team to travel to more than 200 locations where fish may be found in the Silurian strata in China, and finally found the "Chongqing Special Buried Fossil Bank" in the early Silurian strata in South China. " and "Guizhou Shiqian Fossil Bank", found a large number of complete and preserved early Silurian fish fossils, and found the "key" to unravel the mystery of the initial rise and radiation differentiation of jaws.

  The "Guizhou Shiqian Fossil Library" dates from the early Silurian period about 439 million years ago, and contains a large number of well-preserved jaw-like microfossils.

Among them, the tooth spiral of the fossil of "Double-column-toothed fish" represents the oldest jaw-like teeth, pushing forward the earliest fossil evidence of jaw-like teeth by 14 million years.

The discovery of the spines of the "Xin-plastic Fanjingshan fish" shows that as early as the early Silurian period, the primitive cartilaginous fishes had evolved the typical form of the spines and had the histological characteristics of teleost fishes.

These research advances have also settled the long-standing debate over the taxonomic location of Ordovician and Silurian fish scales and spiny fossils.

  The "Chongqing Special Buried Fossil Repository" about 436 million years ago is currently the only special burial fossil repository in the world that preserves the complete jaw fossils of the early Silurian period. It can be called "the dawn of fish".

After the Chengjiang Biota and the Jehol Biota, it is another world-class special burial fossil bank discovered in China that provides a large amount of key evidence for the exploration of important nodes in the evolution of the tree of life, and pushes forward the complete fossil record of jaws. 11 million years ago and traces the origin of several human body structures to fossil fish 436 million years ago.

  Zhu Min pointed out that the ancient fish fossils found in the "Chongqing Special Buried Fossil Repository" are not only numerous and complete in variety, but also very complete and beautifully preserved, allowing people to have a glimpse of the whole picture of vertebrates in the early Silurian period, especially the jaws.

Among them, the jawless armored fish "Smart Tujia fish" provides key fossil evidence for the origin of paired appendages in vertebrates; the jawed "Shen's stickleback" is the earliest well-preserved cartilaginous fish known so far, confirming that Sharks evolved from the ancestors of "wearing armor and wearing armor"; another jawed fish, "Miracle Xiushanyu", combines the characteristics of multiple placodes to explore the main groups at the root of the jawed tree of life. The origin and evolution of vertebrate skulls provide valuable information.

Academician Zhu Min shows the cover image of "Nature" of the research paper "From Fish to Man".

Photo by China News Agency reporter Sun Zifa

What is the significance and impact of the latest research progress on jaws?

  Zhu Min said, "Chongqing Special Buried Fossil Bank" and "Guizhou Shiqian Fossil Bank" and the discovery and research of the five species of fish are the first large-scale display of the Silurian fish groups, especially the jaws, in the history of paleontology. Reveals the process of the rise of the early jaws - at the latest 440 million years ago, the major groups of jaws have emerged and prospered in South China, "It can be said that South China is the rise, radiation and differentiation of jaws on the earth. "cradle" and center"; by the late Silurian, more diverse and larger jawed species appeared and began to spread across the globe, initiating the process of fish landings and eventual evolution into humans.

  The research team applied new technologies and new methods such as high-precision CT (computed tomography), big data analysis of traits, and hydrodynamic simulation to study 5 species of fish fossils in two fossil banks in Chongqing and Guizhou, showing the world for the first time the earliest jaws The teeth, head, body, and even fin rudiments were completely unknown in the past, and the earliest jaw-like body structure and anatomical information provided conclusive evidence for answering a series of important scientific questions in the initial stage of "from fish to man". It also rewrote various aspects of the early evolutionary history of jawed vertebrates.

  Chinese scientists have made new progress in the exploration of important scientific issues such as the earliest differentiation of jaws, the evolution of important organs and body configuration, and refreshed traditional cognition.

At the same time, this time, many human-related anatomical structures were traced back to ancient fish 440 million years ago, filling the most initial missing link in the evolutionary history of "from fish to man". The update of knowledge also further consolidates the evolutionary path of "from fish to man".

  Regarding the latest progress in the research on jaws by Chinese colleagues, former President of the International Society of Vertebrate Paleontology and Professor John Long of Flinders University in Australia wrote, "This is indeed an amazing fossil that changes the evolutionary pattern. The discovery has rewritten nearly every aspect of the early evolutionary history of jawed vertebrates."

Researchers show an ancient fish fossil specimen for this study.

Photo by China News Agency reporter Sun Zifa

How to further develop jaw related research in the future?

  As a top international academic journal, it is quite rare for "Nature" to publish four research papers by the same team at the same time. In the view of Academician Zhu Min, this is a long-term achievement of their team. On the other hand, it also shows that international academic The recognition of the research work of the Chinese team by the community also reflects the important international status of Chinese scientists in the field of paleontology research.

  On the basis of this important breakthrough, what plans and arrangements will the Chinese scientific research team have for the subsequent research on jaws?

Zhu Min said frankly that only a small part of the research work in the early Silurian period has been reported, and the research on a large number of fish fossils found in the two fossil banks in Chongqing and Guizhou will continue for a long time.

  At the same time, a more extensive search for jawed fossils should be carried out in contemporaneous strata, including molecular clocks and scattered fossil records, which indicate that the origin of jaws may actually have occurred 450 million years ago or even earlier. The oldest jaw fossils studied in this study were about 439 million years ago, and there are still many gaps in the fossil record, requiring paleontologists to go to older, earliest Silurian or even Ordovician strata Search, which is also a challenging field of work in the future.

  Zhu Min pointed out that there are actually many environmental background studies that need to be carried out to help people better understand how radiation evolution occurred in the early jaws: Why did radiation evolution not occur in the Ordovician?

And radiation evolution occurred in the early Silurian?

What was the geological environment in South China at that time?

How did the environment in South China differ between the late Ordovician and the early Silurian?

What is the impact on the evolution of jawed radiation?

  He believes that there are still many scientific issues that require continuous and in-depth research in the future of the evolutionary radiation of "from fish to man". Therefore, the progress made in this discovery and research is only the "first step of the "Long March", and there are still very important follow-up issues. Research work will further bring new knowledge and even more surprises.

  Zhu Min said that scientific research is a step-by-step process of exploration. In fact, the more you go back in the exploration of the source of "from fish to man", the more unknown things will be, and many new challenges will be presented to the research team.

It is foreseeable that the newly discovered "Chongqing Special Buried Fossil Repository" and "Guizhou Shiqian Fossil Reservoir" will continue to contribute to solving more mysteries surrounding the origin of jaws in the future.