When we excavate marine sedimentary rocks 500-300 million years ago and break them up randomly, there may be tens of thousands of chitin fossils. They are so small that they can hardly be seen by the naked eye, but they were the sea lords hundreds of millions of years ago. Nowadays, they sleep quietly in rocks and play an important role in chronostratigraphic and biostratigraphic correlation, making great contributions to the search for oil and gas resources. On September 2, the reporter of science and technology daily learned from Nanjing Institute of Geology and paleontology, Chinese Academy of Sciences, that Liang Yan, an associate researcher of the Institute, cooperated with Chinese and foreign counterparts to carry out research on the biological properties of chitin beetles and obtain new understanding. The related research results have been published online in the international geoscience journal Geology. Chitin is a kind of micro organism living in the ocean from Ordovician to Devonian (480-260 million years ago). It is just like a bottle and a jar. It is only a few hundred microns long. It has a radiation symmetrical organic shell outside and a soft body inside. Unlike other creatures, it has a unique mouth cap or mouth plug to close the body, just like a floating bottle in the sea. In the past, some scientists speculated that it was a protozoan similar to ciliates and foraminifera. “Compared with the pods, ciliates, flagellates and foraminifera, they do look very similar, but none of these insects has the mouth cap or plug like a chitin.” Liang Yan said that the cover and plug also made scientists very puzzled, “it is still unclear how the chitin insect, a completely closed shell, can obtain food from the external environment and how it excretes its excreta.”. In 1963, with the appearance of a number of specimens like insect eggs, some scientists believe that they are the eggs or oocysts of some metazoan. Chitins are a kind of fossils that can be easily obtained in the strata. However, researchers have never found a young chitin, let alone a reproductive specimen, so they think it is an unknown zooplankton egg. Until now, this is the mainstream theory. In recent years, Liang Yan, in cooperation with colleagues at home and abroad, put forward new views on the biological properties of chitin beetles. “Through the study of 331 well preserved chitin fossils, we found that their morphological changes were obvious, and they all gradually changed from short and fat to slender. The ornamentation of spines is also continuous, from simple spines in the mouth to multiple spines in the middle, and then to plexiform spines at the bottom, which are becoming more and more complex Liang Yan told reporters that this means that chitins grow vertically, which is far from the theory that chitins are eggs. < p > < p > in order to further explore the identity of chitins, the scientific research team collected the maximum and minimum shell length ratio of 378 species of chitins in 57 genera, and the egg sizes of 45 aquatic invertebrates of 6 phyla, 10 classes and 10 classes. The results showed that chitinas were not invertebrate eggs. “We believe that chitins are an independent class of ancient marine micro organisms.” Liang Yan said. < / P > < p > the scientific research team has found hundreds of fossils by means of near-infrared microscopic imaging, micro CT, double beam electron scanning and field emission electron imaging. In the past, it was regarded as a special specimen of aberrations, which was actually the stop frame of chitin reproduction. < / P > < p > observing these tiny fossils under a microscope, the reproduction process of chitins is like squeezing toothpaste: first of all, a larva with the same shape and a slightly smaller individual will emerge from the bottom of the mother. When the larva grows a shell in the mother, it will separate from the mother, and the “hole” at the bottom of the mother will gradually retract and disappear. Some chitins produce one larva at a time, and some produce a bunch of them. These two reproductive modes are similar to budding and transverse cleavage respectively, but they are obviously different. Liang Yan said that since 1937, scientists have discovered such precious specimens. However, due to the lack of technical means and the small number of specimens, these specimens were treated as abnormal and variant specimens. The researchers also found a hole in the bottom of the larvae. “This structure is also very important. There was no such hole in previous specimens.” Liang Yan said that this indicated that chitins could exchange substances with the external environment during reproduction until the next reproduction, similar to hibernation of snakes and bears. “We have studied the ultrastructure and reproductive pattern of chitinas, and combined with the morphological characteristics of chitinas with radially symmetric shells, extensive paleogeographic and ecological distribution, and significant intraspecific differences, we conclude that chitins are more likely to be independent protozoa than metazoan eggs or oocysts.” Liang Yan told reporters that understanding the biological properties of chitins is important for the study of chronostratigraphy and microflora evolution, “it helps us to find oil and mineral resources, but we don’t know what it is. This progress is of great significance to the follow-up study of biostratigraphy and biodiversity. Didi Qingju bicycle has entered 150 cities