Can you imagine? About 300 million years ago, around the inland city of Yangquan, there was still a shallow sea close to the equator and suitable for all kinds of marine life, and there were flocks of marine overlords, sharks, bathed in warm sunshine, swimming freely in this sea.
This is not a story, on August 25, the international academic journal "Geological Journal (English Edition)", with a cover article to report on the permian Ural Taiyuan Formation in Yangquan City found in the Permian Ural Taiyuan Formation formation of the petal-toothed shark fossils, which means that the fossils in our province have added another marine overlord - sharks.
A total of 15 fossilized teeth of the flap-tooth shark were excavated
As a fierce top predator in the ocean, the fossils of sharks appear in the mountain city of Yangquan inland, which can't help but amaze people. How did shark fossils appear in Yangquan? How were these fossils discovered? What kind of shark is the flaptooth shark found this time? What are the major scientific implications of this discovery? With many questions, the Shanxi Evening News reporter interviewed Bai Zhijun, one of the participants in the study of the fossil of the flap tooth shark, Bai Zhijun of the Yangquan Municipal Planning and Natural Resources Bureau.
Bai Zhijun is the discoverer of the fossil of the flap-tooth shark, because of the needs of the work, he has carried out a long-term and large number of field investigations in the Yangquan area, and has found a series of important paleontological fossils such as the Bai's Peach River Beast, the Yangquan Longevity Salamander, the Mixed Yangquan Wood, and the Mei's Damde Wood. "If the geological rock formation is compared to a heavenly book that records the history of the earth, then the fossil is the most intuitive and understandable text of the earth's history book." Bai Zhijun said.
Bai Zhijun told reporters that the research on the flap tooth shark began on December 12, 2019, during which two teachers, Gai Zhikun and Lin Xianghong of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, as well as Zhang Junwen of the Yangquan Branch of the Second Provincial Geological Survey Institute, jointly participated in the excavation of the fossil.
When the research team conducted a comprehensive investigation of the limestone layers of the Benxi Formation and Taiyuan Formation in Yangquan District, it was found that the marine life fossils in the Qian limestone layer of Pingshang Village on the outskirts of Yangquan City were the most abundant, and were formed by a set of biological fossil accumulations, of which the echinoderm sea lily was the most abundant, with the thickest point reaching 2.6 meters. The brachiopods in the rocks are mainly long-bodied shells, followed by stone swallow shells, and there are abundant fossils of gills such as sea fans, which are much larger than other areas of the Same Layer of Yangquan, and the largest stone swallows and sea fans can reach 18 cm.
In 2020, just in time for the outbreak of the new crown epidemic, two teachers, Gai Zhikun and Lin Xianghong, could not go to Yangquan to work on the spot, so they bored their offices in Beijing, flipped through domestic and foreign research materials, and conducted comparative research. Bai Zhijun was responsible for continuing excavations at the Yangquan fossil site, with the assistance of Zhang Junwen. Over a period of three months, they unearthed 15 fossils of the teeth of the flap-tooth shark. After many discussions and field confirmations, the research team grinded, measured and analyzed the data of the fossils, and finally selected the best preserved 7 teeth to complete the research work.
What kind of shark does the flaptooth shark look like?
According to Lin Xianghong, the flap tooth shark is a primitive cartilaginous fish that mainly lived in the Carboniferous to Permian period (about 360 million to 250 million years ago), and in terms of the size of the teeth, their teeth are similar to the teeth of the living great white shark, and it can be inferred that the flap tooth shark is a type of prehistoric giant shark with a body length of up to 3 meters to 5 meters. The flap-toothed shark is a worldwide species of fossils widely distributed in major regions of the Northern Hemisphere, including England, Italy, Russia and North America, and has not yet been found in the Southern Hemisphere. Since the bodies of cartilaginous fish are mostly difficult to preserve, the fossils of flap-tooth sharks found so far are scattered teeth.
The scattered state of fossil preservation suggests that the flapped tooth shark, like most sharks today, has teeth that are replaced for life, that is, the lost teeth can be replaced by new teeth. Because the flap tooth shark has only found fossil teeth, the academic community has not accurately understood the complete morphology of this animal for a long time, but researchers can still sketch the general appearance of these ancient killers based on scattered fossil tooth specimens.
Conventional wisdom holds that they are benthic, slow-moving shell-eating fish that feed on benthic brachiopods, bivalves, and other shelled organisms (benthic organisms are organisms that inhabit the bottom or surface of the ocean or inland waters). But from the existing tooth fossils, the unique shape of the flapped tooth shark teeth suggests that it may be another way of life: the edge of the bladed tooth is covered with a large number of vertical grooves, and it also has a huge bite surface, which may be more suitable for biting the muscle tissue of the prey.
The study suggests that the horizontally stacked tile-like ridged stripes that surround the base of the coronal teeth of the flap-tooth shark may have the function of preventing the escape of prey by increasing friction when the teeth pierce the muscular soft tissue. Therefore, the ecological niche of the flap-toothed shark may resemble that of the modern great white shark, which was the top predator in the Paleozoic ocean. The flap-toothed shark's discovery in China and Japan outside Europe and the United States suggests that it has transoceanic migration capabilities and is most likely a type of predator with strong swimming ability, rather than the benthic crusts originally thought.
What are the major scientific implications of the discovery of the flap-toothed shark?
Gai Zhikun, an associate researcher at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, introduced that the flap tooth shark fossils found in the Permian Ural Taiyuan Formation Qian limestone layer in the Yangquan area are the first discovery of tooth fossils of the genus in China. It enriches our understanding of the biodiversity of the Permian Ural period in North China, and greatly expands the paleogeographic distribution range of the flap-tooth shark in the northern hemisphere.
The study focused on the investigation of flap-tooth sharks and related biota in the Qian limestone layer of the Taiyuan Formation in the Yangquan region, dating from the Ural Athol period to the Sakkmal period in the Permian period (about 290 to 298 million years ago). As a set of biological sedimentary clastic limestone, the money limestone layer is rich in a large number of marine lily stem fossils that resemble ancient coins (so called the money limestone layer), in addition to a large number of brachiopod fauna represented by long-bodied shells and stone swallows and other marine life fossils represented by cephalopods, which indicates that nearly 300 million years ago, Yangquan was a shallow sea close to the equator warm and transparent light, which is very suitable for the survival of all kinds of marine life.
Many people may ask, shark fossils appeared 290 million to 298 million years ago, how is this time determined? Bai Zhijun told reporters: "Like the history of mankind, there is a detailed annual representative, the evolutionary history of the earth also has a detailed annual representative, but this year represents a million years as a unit, the absolute age of this year representative is measured by radioactive isotopes, and then this year represents different kinds of organisms in different eras, just like different dynasties in history have different representative porcelain." We usually use some marine, globally distributed organisms with a rapid rate of evolution as standardized stones for global comparison to determine the relative age of fossils. For example, the fossil of the flap-tooth shark tooth found this time is symbiotic with a single-celled biometric stone called (worm plus ace), so that we can easily determine that the era of the flap-tooth shark belongs to the Permian Ural Atsur to the Sakkomar period, so that we can check this absolute age on the surface of the latest international chronological stratigraphic period released by the International Stratigraphic Commission. ”
How can these fossils be protected?
Bai Zhijun said that after several years of efforts, a large number of paleontological fossils with important scientific research value have been found in Yangquan, which are of great scientific significance for revealing the earth's paleogeography, paleoenvironment and biological evolution. At the same time, studying Chinese fossils and telling Chinese stories well is also of great significance to the construction of national cultural self-confidence and spiritual civilization.
It is understood that the Yangquan Municipal Party Committee and Municipal Government attach great importance to the protection, development and utilization of paleontological fossils. At present, Yangquan City has carried out the declaration of "the national important paleontological fossil concentrated production area"; it has also carried out the investigation of the paleontological fossil resources of Yangquan City; invited experts from the Chinese Academy of Sciences to carry out research on paleontological fossils in Yangquan; built the Nanshan Park Fossil Science Popularization Park, and built the No. 1 Pit for Fossil Protection that preserves the country's coarsest Kodamu in Sanquan New Village; and carried out a wealth of outdoor fossil science popularization and research activities.
Regarding the fossils of the flap tooth shark reported in this study, the Chinese Academy of Sciences hired Yang Dinghua, a famous paleontological fossil restorer in China, to draw a restoration map for the flap tooth shark, which was covered by the fourth issue of the international academic journal Acta Geologica Sinica (English Edition) "Geological Journal (English Edition)". At the same time, she also asked Ms. "Yufeng", a beautiful cartoonist from the Pangu Fossil Museum in Zhejiang, to draw cartoons on the flap-toothed shark found in Yangquan, which greatly facilitated people's easy understanding of this ancient shark.
You may be curious, how can you restore the entire shark picture through the fossils of the teeth? Bai Zhijun told reporters, "'Will be ancient' is an important law of paleontological research, the restoration of the flap tooth shark is a reference to the living shark; the other currently has two complete flap tooth shark fossils can peek into its full picture, one is from montana Belantexi shark, the other is from Germany and northern England Janassa shark, we also refer to these two specimens to restore the flap tooth shark." Of course, if one day we are fortunate enough to discover a complete specimen of the flap-tooth shark, it is possible that our recovery today will be completely overturned, and this is how science moves forward in a step-by-step correction. ”
In order to protect the precious fossil resources, Yangquan has been the discovery of the flap tooth shark for protection, the fossil is located in the village committee has a special person to take care of, the natural resources law enforcement department irregular inspection, Yangquan Municipal Bureau of Culture and Tourism will also take fossil tourism as a future development plan, Yangquan Municipal Planning and Natural Resources Bureau is also actively attracting investment, looking forward to the early Yangquan fossil into a famous tourism culture business card of our province and even China.
Fossil research has a long way to go
According to Gao Jianping, senior engineer of the Provincial Natural Resources Development Center, in recent years, Yangquan has found a large number of paleontological fossils, and has also achieved many important paleontological fossil research results that are internationally recognized, and Yangquan has become a famous fossil production area in China and even in the world.
Yangquan is located in the transition area between the Loess Plateau and the North China Plain, the territory is mainly mountainous landforms, many typical geological profiles are well exposed, in addition to volcanoes, caves, hot springs and Taihang Mountain and other rich geological relics landscape. As early as the end of the Qing Dynasty to the Republic of China, Ding Wenjiang, Li Siguang, Wang Zhuquan and other giants of China's geological undertakings carried out a large number of pioneering and foundational geological research work in Yangquan. Yangquan has found many important paleontological fossils, of which the national key protection is: Carboniferous to Permian (the earliest 315 million years ago) our province is the oldest, the largest number, composed of 591 wood fossils of large wood fossils; in addition to the discovery of tetrapod fossils older than dinosaurs, there are the world's first discovery of new species such as the Bai's Peach River Beast, Yangquan longevity salamander and precious sawtooth dragon fossils. The fossils of paleontology that are not under key protection are more abundant, and rare Paleozoic insect fossils have been found in China; 216 species of plant fossils in the coal-forming period have been found; and more than 200 species of marine invertebrates have been found.
Shanxi Geological Museum uses Yangquan as a field practice base for learning geology and paleontological knowledge, and has organized museum staff and volunteers to visit Yangquan for many times. Outdoor groups and research and education groups from Beijing, Taiyuan, Shijiazhuang and other places have also visited Yangquan to visit paleontological fossils, making the fossil tourism industry in Yangquan City begin to take shape.
There is a Zen saying: "Looking at the mountain is a mountain, looking at the mountain is not a mountain, looking at the mountain is a mountain." Bai Zhijun said that it is most appropriate to use this sentence to describe the geological people looking at the mountains. Because the earth has been in the vicissitudes of the sea countless times, very few can be recorded by geological rock formations. We have always been proud of the "five thousand years of civilization", but we do not know that the earth has a 4.6 billion years of evolution history, from a hot fireball gradually cooled, until the production of water, life from scratch, from simple to complex, the earth's land has undergone the aggregation and disintegration of plates, the sea level has experienced countless rises and falls, and finally the formation of the current seven continents and four oceans. "Paleontological fossils are important evidence for us to discover and study the earth, and they are also non-renewable precious natural resources, so the protection and rational development and utilization of paleontological fossils can be described as a long way to go." Bai Zhijun said. Shanxi Evening News reporter Wen Lifang