The death of the entire species is referred as the extinction of that particular species. The extinction of species is caused due to the sudden change in the environmental factors in which it becomes difficult for the species to adapt the environment. Humans may also be one of the reasons which led to the extinction of various animals. The Extinction Ancient Hierarchy thus includes the classes of ancient animals who got extinct due to some natural or unnatural factors. Thus the animals existing millions of years ago who got extinct forms the basis of the Extinction Ancient Hierarchy.
The earth witnessed different eras globally and with the end of a particular era, various species got extinct. In the Precambrian age which consisted the geological time of 650 million years ago and consisted diverse range of species and over 70 percent of species got extinct during that period. Followed by the Cambrian era about 510 million years ago witnessed the extinction of 60 percent species. At the end of Ordovician era, 440 million years ago, 75 percent of the species got extinct. In the similar way in Permian era about 248 million years ago maximum number of species got extinct with the percentage factor of 95. 65 million years ago Cretaceous era existed and during that period up to 85 percent species got extinct.
Due to some critical factors, an extinct species failed to survive on the earth. Earlier it was realized that marine species are more resistant to extinction as compared to the terrestrial species but however it has been observed that there is a huge drop in the marine species due to extinction. Some scientists believed that the extinction of species is only caused due to the change in climatic factors which are not adaptable by the species. The existence of the ancient species was evidenced by the scientists with the help of the remains of the species that is, their fossils, carcasses, teeth etc.
Various ancient species which got extinct includes Megalodon, Archelon ischyros, Meganeura monyi, Glyptodon and Baluchitherium. The term Taxonomy is used to describe the species in the Extinction Ancient Hierarchy. With the help of this phenomenon it has become easy to identify the species even in its ancient times. According to this concept, the species is recognized by two factors and these are the genus and the species name. Some of the extinct species were identified with the help of the famous Darwin theory also.
The Extinction Ancient Hierarchy listed all the extinct species of history along with their attributes. With the help of some bones buried deep under the earth helped to identify the Extinction Ancient Hierarchy of numerous species. Various other evidences buried beneath the crust supported the theories adopted by the scientists. The bones are only studied by the scientists dealing with this ancient Hierarchy of species and they are capable of determining various records like the shape of the species, its size, its length etc. These historical records serve as the basis to each and every class of the species in this Hierarchy.