Cambrian explosion of life is still known as a major unsolved case in paleontology and geology, when the earth entered the Cambrian, living species suddenly flourished, starting from 530 million years ago, about 20 million years, many categories of arthropods, brachiopods, demodex, sponges, chordates and other invertebrate fossils suddenly appeared, but in the early more ancient strata, but has not yet found its ancestral fossils. Therefore, the phenomenon of life species that suddenly appeared during this period was called "Cambrian explosion of life" by paleontologists, also known as "Cambrian explosion".
The Cambrian life explosion has sufficient evidence in the strata to prove that the Chengjiang biological fossil group in Yunnan, China, the Burgess biological fossil group in Canada and the Kaili biological fossil group together constitute the world's three major Cambrian shale-type biological fossil groups (the recently excavated Qingjiang biological fossil group in the Changyang area of Yichang, Hubei Province, China also belongs to the Cambrian biota). They vividly reproduce the magnificent landscape of ancient marine life and the original characteristics of living animals, providing direct evidence for the "Cambrian explosion" study with rich biological information. For example, there are more than 120 species of fossil biota in Chengjiang, Yunnan, China, which belong to more than ten animal phylums such as sponges, coelenterates, brachiopods, gill-draggers, leaf-legged animals, mollusks, arthropods, echinoderms, chordates, etc., as well as some strange taxonomic groups with unknown taxonomic positions and a variety of symbiotic seaweeds.
These fossil groups miraculously preserve the mineralized bones of many living species, and also preserve a large number of soft tissue imprints, such as: epidermis, tentacles, cilia, eyes, intestines, stomach, digestive glands, mouth and nerves, etc., and even some animal digestive tracts are still recognizable for food. Biologists have continuously excavated and deeply studied these animal fossil groups, explored the origin of arthropods, claws and carapaces in invertebrates, confirmed that the phylum and subphylum of living animals and complex ecosystems originated in the early Cambrian period, challenged the bottom-up inverted cone evolutionary theoretical model, and provided fossil evidence for the top-down explosive theoretical model.
So why did life species on Earth suddenly erupt in the early Cambrian period? In fact, at the beginning of this article, it is said that this is still a big unsolved case, that is to say, this mystery has not been solved today, but biologists have put forward various hypotheses, such as the Cambrian biological mutation proposed by Chen Junyuan researcher in the field of archaeological biology in China has a very obvious idea of spontaneous evolutionary behavior, the hypothesis is that the early Cambrian life species suddenly encountered an extremely suitable period for survival, the earth's temperature, humidity, climate, oxygen content, etc. are very suitable for the survival of living species. Therefore, in different ecological environments, living species have also evolved towards different morphological characteristics, and phyla have begun to be complex and diverse, so the phenomenon of a large explosion of living species has emerged.
There are also a variety of hypotheses, which are also believed to be related to environmental changes caused by the impact of a celestial body on the Equatorial Region of the Earth. In fact, this phenomenon is mentioned in Darwin's "Origin of Species", and he believes that this fact can be used as evidence against his theory of evolution. But he and other biologists still believe that although Cambrian species showed great explosions, the ancestors of these species of life were still Precambrian creatures. The "suddenness" of Cambrian fossils and the lack of Precambrian fossils may be due to incomplete geological records or to the submergence of old strata in the ocean.
Traditional and classical biological theories still hold that biological evolution has undergone a long evolutionary process from aquatic to terrestrial, from simple to complex, from low to high, which was gradually realized through the slow rolling of the two wheels of natural selection and genetic variation, and that the Cambrian explosion of life event was not enough to challenge this evolutionary idea.