Luo Ping strong fish restoration diagram. (Quoted from Xu, 2019)
Luo Ping strong fish
（Robustichthys luopingensis）
■ Taxonomic Position: Suborder Ray-finned fishes - Neofinfish - Whole bone fish - Nearherring - Prophetic fish - Strong fish
■Fossil origin: Luoping County, Qujing City, Yunnan Province
■ Strata and era: Middle Triassic Annihilation Guanling Formation Section II
■ Naming people and naming eras: Xu Guanghui, Zhao Lijun, Michael Coates; In 2014
Luo Ping strong fish fossil. (Quoted from Xu, 2019)
The earth has never stopped changing since its birth, and the emergence of living things has added color to this wonderful process. On the dizzying scroll of life, fish can be said to be the most colorful depiction. It is these familiar aquatic creatures that have evolved powerful jaws, perfect nostrils and strong limbs through thousands of dangers, and finally brought vertebrates to land. These "hard-working" fish ancestors are now sleeping in Qujing City, Yunnan Province, known as the "hometown of fish" and "ancient fish kingdom". And the protagonist we want to introduce today is a "big guy" who has been "awakened" here in recent years - Luo Ping Strong Fish.
A veritable hunk
Luo Ping Strong Fish got the name is appropriate. The Latin genus name "robust" means large and powerful, so its Chinese genus name is translated as "strong fish". Its total length (length from head to tail) can reach 40 centimeters, and many structures on the fossil can be distinguished with the naked eye. Although fish that are 40 centimeters long or larger are common today, it is not an exaggeration to say that they are behemoths in southern China during the Triassic period.
Let's see what kind of body shape Luo Ping's "relatives" of strong fish are. The average total length of the bizarre panxian fish and the Xingyi Asian scalytooth fish, also from the Triassic strata of South China, is about 20 cm; The Guizhou Chinese true jaw fish and triassic rejuvenation fish are even smaller, with an average total length of only about 7.5 cm. In this comparison, it is not difficult to find that Luo Ping's strong fish is really a well-deserved big man. In fact, Luo Ping strong fish is the largest whole bone fish species found in the Middle Triassic strata in the world, which can be described as the "world-famous" Chinese big fish.
Such an eye-catching fish has its own little trouble behind the spotlight - for a long time, it did not know who its siblings were. This requires scientists to help it.
Whose baby is it
Luoping strong fish was first reported in 2014, when there were only eight poorly preserved specimens. Because many bone features are not clear-cut, scientists disagree on classifying it.
In the course of the discussion, the focus was on the question of whether it belongs to the nearherring class or a reamed fish. Nearherring and reamingeous fishes are two taxa of whole bone fishes that are closely related but still have many morphological differences. For example, proponents of classifying Luopin strong fish as a hinged fish argue that it lacks the structure of the "mandibular double joint" (i.e., the articular processes of the square and continuing bones, and the corresponding fossa on the mandible), which is important evidence to distinguish near herring from reamed fish.
In fact, it is common in paleontological research that a species is difficult to classify due to the scarcity of fossil materials. We often just have to wait for more fossils to be unearthed, and the thorny problem can be solved. Sure enough, Luo Ping's "two battles" of strong fish had results in 2019. In the past few years, 9 more specimens have been excavated and studied. Relying on intact new specimens, scientists completed some vague features of Luo Ping's strong fish, and the "mandibular double joint" structure was also found in new individuals.
At this point, we have finally figured out which fish are the "blood relatives" of Luo Ping's strong fish, and Luo Ping strong fish has officially joined the legendary family of "near-herring".
Fossil mining site No. 1 in Luoping Biota National Geopark. Photo by Mao Hong
Not only is the size big, but the "generation" is also big
The reason why the near-herring class is legendary is because there is still a living species in this group, it is the bowfin fish. The earliest fossil record of this fish dates back to the Jurassic period, and they are still active in the rivers of North America and are out-and-out living fossils. The Luoping strong fish and the bowfin fish are very closely related, and they belong to the prophetic fish order and the bowfin fish order under the near herring class, respectively.
It is predicted that the fishes are not as lucky as the bowfin fishes and that their members are extinct. Fossilized distributions of prophesied fish are found in Asia, Africa, Europe and the Americas; Four species of prophetic fish have also been found in South China: Xingyi Asian scalytooth fish, strange panxian fish, triassic rejuvenation fish and Luoping strong fish. Luo Ping Strong Fish has a taxonomic status in the order of prophetic fish close to the basal stem and is an ancient member. This is the result of phylogenetic analysis based on its less progressive characteristics. It seems that if the latecomers see it, they will call "ancestors".
Revelations for the aftermath of the disaster
After the Earth entered the Phanerozoic, a total of 5 mass extinction events occurred. The mass extinction event at the end of the Permian is the most destructive of them. In this unprecedented catastrophe, about 90% of marine life and about 75% of terrestrial life failed to withstand the weight of the disaster and became extinct. But the survivors tenaciously passed on their lives.
In the Middle Triassic Age, where natural conditions are relatively friendly, life has a rare time for peaceful development, and all living beings shoulder the mission of reviving the earth's biosphere. Luo Ping Strong Fish is in such a big environment, as a "guide", looking for the answer to survive for his kind in the future. Its fossils offer a glimpse into how Earth's ecosystems are recovering from tragic sacrifices.
In addition, scientists believe that the discovery of Luo Ping's strong fish in Qujing City means that the lower limit of the survival of the predicted fish group has expanded from the Late Jurassic to the Middle Triassic, that is, the occurrence of the predicted fish order has advanced by 90 million years; The geographical distribution has been further extended to Asia. This also supports the conjecture that there was an exchange of species on the east and west shores of the Gutethys Ocean during this period.
The fact that a fish fossil can contain such a rich meaning must have amazed many people. Scientists' relentless exploration and interpretation of nature not only shows us the evolution of organisms buried deep with fossils, but also explains the important value of current environmental protection work. Today, Qujing City is committed to protecting fish fossil resources, promoting the popularization of fish fossil science, and telling the "ancient fish story". I believe that in the near future, with the joint efforts of everyone, "Hometown of Fish" will definitely bring a more amazing life epic to the world.
Feng Donghao