How do birds evolved from dinosaurs differentiate into many forms? On April 2nd, Professor Zhang Guojie's team from the Life Evolution Research Center of Zhejiang University, together with domestic and foreign scholars, published the latest research results in the international journal Nature. The joint team conducted research on the classification relationships of birds between different orders and families, and proposed a new bird classification scheme. The new plan has improved the "Tree of Life" of bird species, providing an important foundation for the analysis and research of bird species. World, phylum, class, order, family, genus, and species are traditional biological classification levels. The bird class is a subclass of vertebrates. Since Darwin proposed the theory of common ancestor and natural selection, naturalists have attempted to classify various bird species around the world. Although researchers have solved the classification problems of many biological groups through DNA molecular data, the world of birds is complex and the veil of evolution is still difficult to uncover. Years ago, Zhang Guojie, together with domestic and foreign scholars, launched the Ten Thousand Species of Bird Genome Project (B10K), aimed at organizing the collection of genomic and morphological information of over 10000 living birds worldwide, and constructing the "Tree of Life" of bird species. So far, the plan has completed research and development at the "objective" and "scientific" levels. Based on the genomic data collected at the "family" level, the team collaborated to construct a "Tree of Life" covering 92% of the current bird families and 218 family groups worldwide. This study is an important achievement of the second phase of the 10000 bird genome project. Zhang Guojie's team and collaborators divided the new bird subclass, which emerged from the radiative evolution of bird outbreaks over 60 million years ago, into four major categories based on the inter gene alignment sequence dataset: the Miracle Bird represented by the Flamingo, the Pigeon Bustard class including pigeons and azaleas, the Land Bird class including sparrows, parrots, and eagles, and a classification called Elemental Birds. Among them, Elemental Birds is a new taxonomic concept proposed by Zhang Guojie's team, which is a large group between "class" and "order", containing 10 "orders". Elemental birds include crane shaped birds such as seagulls and red crowned cranes that primarily live in water, egret shaped birds such as penguins and albatrosses that primarily live on land, Guyana's national treasure musk pheasants and other birds that primarily live on land, and night owls and swifts that live in the sky. Research shows that 95% of living birds belong to new species, and their common ancestors have experienced a large-scale species outbreak in history, rapidly evolving a large number of new species in less than 10 million years. Whether this radiation evolution event occurred before or after the mass extinction, there have been two different hypotheses of "large-scale survival" and "big bang" in the scientific community. The "Massive Survival" hypothesis suggests that prior to the mass extinction event, new birds had undergone rapid radiative evolution and survived the subsequent drastic global changes; The "Big Bang" hypothesis suggests that its rapid differentiation occurred after the mass extinction event, and early new birds spread to the newly formed positions left by the extinction event, followed by rapid radiation adaptation evolution. Fossil evidence further supports the "Big Bang" hypothesis, but earlier studies on small-scale gene classification support the "large-scale survival" hypothesis