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The timeline of the evolutionary history of life represents the current scientific theory outlining the major events during the development of life on planet Earth. Dates in this article are consensus estimates based on scientific evidence , mainly fossils .
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
The timeline of human evolution outlines the major events in the evolutionary lineage of the modern human species, Homo sapiens, throughout the history of life, beginning some 4 billion years ago down to recent evolution within H. sapiens during and since the Last Glacial Period.
SEE ALSO: Meet the happiest animal on Earth. 14-30,000 BC: Dogs. 8500 BC: Sheep and Cats. 8000 BC: Goats. 7000 BC: Pigs and Cattle. 6000 BC: Chickens. Check out these furry animals: 5000 BC ...
Figure 1:In mammals, the quadrate and articular bones are small and part of the middle ear; the lower jaw consists only of dentary bone.. While living mammal species can be identified by the presence of milk-producing mammary glands in the females, other features are required when classifying fossils, because mammary glands and other soft-tissue features are not visible in fossils.
This was the last major animal to be tamed as a source of milk, meat, power, and leather in the Old World. Lascaux aurochs, Stone Age [2] 3500 BC. Sumerian animal-drawn wheeled vehicles and plows were developed in Mesopotamia, the region called the "Fertile Crescent." Irrigation was probably done using animal power.
The idea of a tree of life arose from ancient notions of a ladder-like progression from lower into higher forms of life (such as in the Great Chain of Being).Early representations of "branching" phylogenetic trees include a "paleontological chart" showing the geological relationships among plants and animals in the book Elementary Geology, by Edward Hitchcock (first edition: 1840).
The Paleozoic is a time in Earth's history when active complex life forms evolved, took their first foothold on dry land, and when the forerunners of all multicellular life on Earth began to diversify. There are six periods in the Paleozoic era: Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. [10]