Sinodipterus beibei
■ Taxonomic position: Suborder Flesh-finned fish, order Lungfish, genus Chinese biptera, Babe Chinese biplane
■Fossil origin: Zhaotong City, Yunnan Province
■ Strata and era: Qujing Formation, Middle Devonian Eifel period
■ Named by and date: Qiao Tuo and Zhu Min, 2009
Fig. 1 Bebe Chinese biptera. Fossil A is dorsal view and B is ventral view (cited in Qiao and Zhu, 2009)
Maybe we are all deeply impressed by 2008, but how many people still remember the song "Welcome to Beijing" played on the streets at that time? The names of the five Olympic Fuwa are derived from the homonym of "Welcome to Beijing", the first of which is "Beibei". The etymology of the Chinese biwinged fish described in this article comes from "Beibei", named by Academicians Qiao Tuo and Zhu Min in 2009. "Babe" represents water and fish, and the blessing conveyed is prosperity, just like the ancient fish of the Devonian period, flourishing in large rivers and lakes, when the earth was a thriving and vibrant scene.
"Sino-" means "China" in Latin, and we can see many genus names prefixed with "Sino-", mostly species found on continents. And "-dipterus" means "winged fish" in Latin. The two-winged fish is the most common genus of Devonian lungfish, and "biwing" refers to its possession of two separate dorsal fins. "-dipterus" is widely used in the genus names of lungfish from the Devonian period. "Beibei" is the species name, taken from one of the mascots of the 2008 Summer Olympics in Beijing.
Lungfish belongs to the flesh-finned fish, which first appeared in the early Devonian period and is one of only three groups of carnids that have survived to this day, the other two are empty spiny fish and quadrupeds, which have lived for up to 400 million years. When Devonian lungfish fossils were discovered, four-legged fossils often appeared nearby, which is a feature of the Devonian lungfish fossil production environment. In the same layer where the Babe Chinese biplane was found, it contains fossils of other fish such as shieldfish, claw-toothed fishes and tetrapods. This shows that in the Middle Devonian marine and freshwater environment at that time, biological taxa were very rich, and the overall duration of the Devonian was also long, and the taxa had enough time to communicate and evolve.
From the end of the Silurian to the beginning of the Devonian, the earth's plate experienced Caledonian tectonic movement and other orogeny, land-building movements, the global land area gradually expanded, not only higher plants began to occupy land, animals also began to enter freshwater from the sea and even land, the most obvious group of which is lungfish, and its sister group tetrapods. Early lungfish lived in the ocean, and in the Middle Devonian lungfish began to enter the shallow water environment, and the bipterosis had a large change in the brain and its respiratory capacity compared with the Early Devonian lungfish, and was considered to be the first lungfish to enter the freshwater environment.
The freshwater environment is completely different from the saltwater environment, and the lungfish have to make a series of changes in body structure and habits to adapt to the new environment, such as osmotic pressure, breathing mode, predation mode, living habits, etc., so the lungfish of the Middle Devonian have obvious changes in structure and habit compared with the early lungfish.
Fig. 2 Restoration line diagram of Beibei Chinese biplane fish (cited in Qiao and Zhu, 2009)
In terms of fossil structure, the Chinese biplanes have some more progressive characteristic changes than the early Devonian lungfish: the I bone is separated by the B bone; The B bone does not have a grooved groove; The supraorbital sensory duct and the infraorbital sensory duct meet retroorbital; The E bone is intact and in contact with the C bone; The dorsal side of the medial pterygoid does not have a posterior dorsal process; X and K bone healing; The maximum width of the parietal nail is located before the Yl bone; The parietal nail is not completely healed from the snout; The scales are round. In addition, the tooth plates of the Chinese biplane fish are orthotooth plates, which are very similar to the biplane fish and the Late Devonian lungfish Andreyevichthys. There are many kinds of lungfish with orthodontic plates, which are characterized by enhanced grinding ability of the tooth plate, degeneration of the adductor muscles of the lower jaw, lower posterior skull, shorter postorbital area, smaller gill ventricular cavity, anterior tooth plate, forward movement of the jaw joint, lengthening of the parasphenoid stalk, dense dentin, etc., which are related to their adaptation to the environment. At the same time, there are some differences between them: the inner wing bone tooth plate of the Chinese biplane fish has 7~8 rows of tooth ridges, which is consistent with the Andreevka fish found in Russia, while the tooth ridges in the biplane fish are about 10 rows. The Chinese biplane fish has some scattered small odontoma between the ridges, the same as Andreevka and biplanes, but the distribution of small odontoma in Andreevka fish is more extensive. The inner trim of the toothed plate of the Chinese biplane fish is narrower than that of the Andreevka and biplanes. The Chinese bipterosa has a full column of layers on the parietal nail, which is a more primitive feature than the Late Devonian lungfish. In addition, the inner wing bone of the Chinese biplane fish does not have a structure similar to the whole layer, which can also distinguish it from the biplane fish. At present, there is only one species of Chinese biplane.
Figure 3 Photo of Beibei Chinese biplane fishtooth plate (cited in Qiao and Zhu, 2009)
In order to explore the evolutionary position of the Chinese biplane in lungfish, the researchers conducted a phylogenetic analysis. Phylogenetic analysis showed that the Chinese biplane fish was more progressive than the biptera. The results of phylogenetic analysis showed that there were a large number of parallel evolution and feature reversal in the evolution of Devonian lungfish, which may be related to the rapid radiation of early lungfish in a short period of time.
This also shows that throughout the Devonian, fish flourished and were worthy of the hegemony of the earth, most fish occupied the top of the food chain, and then one of the flesh-finned fish crawled to land, and then always occupied the land. Lungfish in the history of hundreds of millions of years of life evolution, is a special existence, but also plays an extraordinary role, countless species in the long history of the river has long been extinct, countless species in the evolution of the dynasty one after another, but lungfish silently multiplied to this day, trying to survive in every period of the earth, witnessing every history of the earth, perhaps they are favored by God, or they are really not treated by death, nor are they on the menu of higher predators. This amazing fish, from their bodies, we can look through hundreds of millions of years at a glance, we see the rings of history engraved in their genes, planted on their bodies, breathing fish, magical and beautiful.
Qin Jianlu Qiao Tuo