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Principles. The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). [5] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or ...
General periods. Geologic Time – Period prior to humans. 4.6 billion to 3 million years ago. (See "prehistoric periods" for more detail into this.) Primatomorphid Era – Period prior to the existence of Primatomorpha. Simian Era – Period prior to the existence of Simiiformes. Hominoid Era – Period prior to the existence of Hominoidea.
List of decades, centuries, and millennia. The list below includes links to articles with further details for each decade, century, and millennium from 15,000 BC to AD 3000. Century. Decades. 15th millennium BC · 15,000–14,001 BC. 14th millennium BC · 14,000–13,001 BC. 13th millennium BC · 13,000–12,001 BC. 12th millennium BC · 12,000 ...
Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, and into the future. [1] [2] [3] It is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the ...
A timeline is a display of a list of events in chronological order. [1] It is typically a graphic design showing a long bar labelled with dates paralleling it, and usually contemporaneous events. Timelines can use any suitable scale representing time, suiting the subject and data; many use a linear scale, in which a unit of distance is equal to ...
A secondary palate enables the animal to eat and breathe at the same time and is a sign of a more active, perhaps warm-blooded, way of life. [21] They had lost gastralia and, possibly, scales. 260-230 Ma Cynognathus. One subgroup of therapsids, the cynodonts, lose pineal eye & lumbar ribs and very likely became warm-blooded.
Orders of magnitude (time) An order of magnitude of time is usually a decimal prefix or decimal order-of-magnitude quantity together with a base unit of time, like a microsecond or a million years. In some cases, the order of magnitude may be implied (usually 1), like a "second" or "year". In other cases, the quantity name implies the base unit ...
A spacetime diagram is a graphical illustration of locations in space at various times, especially in the special theory of relativity. Spacetime diagrams can show the geometry underlying phenomena like time dilation and length contraction without mathematical equations. The history of an object's location through time traces out a line or ...