Recently, the research team of the Department of Geology of Northwest University conducted big data analysis and shell morphological anatomy research on the shells of tongue-shaped shells over 520 million years, and concluded that the burrowing lifestyle of tongue-shaped shellfish was established as early as the Ordovician period, and its shell morphology and lifestyle diversity (including fixation, adhesion, social living and burrowing) reached a peak. Subsequently, cave-dwelling and gregarious life types were randomly preserved during mass extinction events at the end of the Ordovician and Permian.
The relevant research results were published online in Current Biology, a comprehensive journal of Cell Publishing Group, in the early morning of March 9, 2023, Beijing time.
△Trilobites, dinosaurs, mammals and brachiopods tongue-shaped shell history extension (red lines indicate five mass extinction events)
Brachiopod lingulids were defined by Darwin as "living fossils." It has appeared since the early Cambrian period, and has survived all the tribulations and natural disasters since the emergence of animals on Earth, especially the earth's worst "five mass extinction" events. At present, it is still distributed in the coastal shallow sea areas of Guangxi, Japan, New Zealand and other places on the mainland, and has become a delicacy on the local table.
△ Lifestyle and stratification of brachiopods during the Cambrian explosion (including anchorage, fixation, and attachment life types)
For 520 million years, tongue-shaped shells have been living on the muddy seabed, their shells are 3~5 cm, the largest is not more than ten centimeters, occupying a very limited ecological space, so it is also called "grassroots" animals.
In the long-term evolutionary process, they have continuously explored, changed and hardened the surface of the marine substrate through changeable shell morphology, and reached unprecedented prosperity in the diversity of genera species and shell morphology in the Ordovician period, evolving a variety of shell types including cave life types and grape string group life. It is this accumulation of "diversity" that has made it "sufficiently possible" for brachiopod tongue-shaped shellfish to survive as a natural selection in the face of the five great extinctions of the Phanerozoic, especially the Ordovician and Permian extinction events, which have the highest extinction rate in the Phanerozoic organisms.
Through multidisciplinary cross-studies such as clade analysis, morphological spatial measurement and lineage analysis, the results show that post-Ordovician stochastic evolution is the external driving force that dominates the evolution of modern tongue-shaped shellfish. Therefore, after the Cambrian explosion, the brachiopod tongue shell evolved by natural selection, and the shell diversity was unprecedentedly developed. However, in two or more mass extinction events after the Phanerozoic, strong random selection of straight troglodyte groups on both sides of the shell resulted in natural selection playing little or no role in the long morphological and ecological evolution of tongue-shaped shells after the Ordovician.
Expand your knowledge: Phanerozoic
The Phanerozoic, which refers to the "age of visible organisms", is the stage since the beginning of the emergence of a large number of higher animals, including the Paleozoic, Mesozoic, and Cenozoic eras. From about 540 million years ago, 540 million years ago, at the beginning of the Cambrian, organisms gradually evolved into higher animals, animals have shells and clear bone structures, so it is called Phanerozoic.
(Main station reporter Li Zhi Lei Kai)
Source: CCTV News Client