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All organisms follow a specific sequence in their development, [9] beginning with gestation and ending with death, which is known as the life cycle. Events in between usually include birth, childhood, maturation, reproduction, and senescence, and together these comprise the life history strategy of that organism.
Slight increase in diversity of cold-tolerant ostracods and foraminifers, along with major extinctions of gastropods, reptiles, amphibians, and multituberculate mammals. Many modern mammal groups begin to appear: first glyptodonts , ground sloths , canids , peccaries , and the first eagles and hawks .
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.
The first fully terrestrial vertebrates were reptilian amniotes — their eggs had internal membranes that allowed the developing embryo to breathe but kept water in. This allowed amniotes to lay eggs on dry land, while amphibians generally need to lay their eggs in water (a few amphibians, such as the common Suriname toad, have evolved other ways of getting around this limitation).
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 hominoids are descendants of a common ancestor.. Homo sapiens is a distinct species of the hominid family of primates, which also includes all the great apes. [1] Over their evolutionary history, humans gradually developed traits such as bipedalism, dexterity, and complex language, [2] as well as interbreeding with other hominins (a tribe of the African hominid subfamily), [3] indicating ...
The world’s frogs, salamanders, newts and other amphibians remain in serious trouble. A new global assessment has found that 41% of amphibian species that scientists have studied are threatened ...
The mammalian male reproductive system contains two main divisions, the penis and the testicles, the latter of which are where sperm are produced and usually held in a scrotum. [5] In humans, both of these organs are outside the abdominal cavity , but they can be primarily housed within the abdomen in other animals.