Extinction (extinction)

ancient creatures disappeared over a certain geological period. By nature, extinction can be divided into species extinction and ultimate extinction. The former evolved from the old species, the genealogy is not interrupted, this is the metabolic phenomenon in the evolutionary process, not the real extinction; Biologically speaking, annihilation usually refers to the ultimate extinction. From the scale point of view, extinction and size, the standard is a geological period of "section" disappeared how much, small-scale extinction, slower, generally normal phenomenon; Large-scale extinctions usually occur during the alternating geological times. There have been six large-scale extinctions in the history of the earth. The first occurred 500 million years ago at the end of the Cambhan period, about 50% of the animal's "ko" extinction; The fourth was in the Trident 180 million years ago, about 35 percent of the animals were extinct, the fifth was at the end of the Cretaceous period 65 million years ago, the largest, dinosaurs, chrysanthemums, and so on disappeared, and the sixth time, 10,000 years ago, many large mammals and birds disappeared. The reasons for the extinction are complex, and scholars have come up with a variety of theologys to explain it. Generally speaking, the main reason is that the environmental conditions have changed dramatically, and the biological population has not produced the relevant variation to adapt to the changed environment, so it is extinct.