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The extinction symbol with an X-shaped pictogram of an hourglass.The letter X stands for the first syllable of the word "extinction" Flag with the extinction symbol. The extinction symbol represents the threat of holocene extinction on Earth; a circle represents the planet and a stylised hourglass is a warning that time is running out for many species.
Permian–Triassic extinction event 252 Ma Large igneous province (LIP) eruptions [ 23 ] from the Siberian Traps , [ 24 ] an impact event (the Wilkes Land Crater ), [ 25 ] an Anoxic event , [ 26 ] an Ice age , [ 27 ] or other possible causes
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms .
Extinction is the termination of a taxon by the death of its last member. A taxon may become functionally extinct before the death of its last member if it loses the capacity to reproduce and recover. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively.
Anoxia was another mechanism of extinction; the end-Triassic extinction was coeval with an uptick in black shale deposition and a pronounced negative δ 238 U excursion, indicating a major decrease in marine oxygen availability. [154] Additional evidence for anoxia during the TJME comes from pyrite framboids, which grow in anoxic conditions. [155]
Human extinction or omnicide is the hypothetical end of the human species, either by population decline due to extraneous natural causes, such as an asteroid impact or large-scale volcanism, or via anthropogenic destruction (self-extinction).
The symbol is also used to indicate death (of people) or extinction (of species or languages). [2] It is one of the modern descendants of the obelus, a mark used historically by scholars as a critical or highlighting indicator in manuscripts. In older texts, it is called an obelisk. [3] [a]
Mass extinctions are characterized by the loss of at least 75% of species within a geologically short period of time (i.e., less than 2 million years). [18] [51] The Holocene extinction is also known as the "sixth extinction", as it is possibly the sixth mass extinction event, after the Ordovician–Silurian extinction events, the Late Devonian extinction, the Permian–Triassic extinction ...