Extinction event
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Mass extinctions
Main article: Mass extinction
There have been at least five mass extinctions in the history of life, in which many species have disappeared in a relatively short period of geological time.
Extinctions occur when environments change too fast. Local extinctions can occur, as can mass extinctions: they differ in scale, scope and the numbers of species involved.
extinction -- When all the members of a clade or taxon die, the group is said to be extinct.
extinction The elimination of all individuals in a group, both by natural (dinosaurs, trilobites) and human-induced (dodo, passenger pigeon, liberals [:)]) means.
Extinction coefficient (å) A measure of a compound's ability to absorb light, given in units that are the reciprocals of molarity and distance in centimeters (M-1 cm-1).
Extinction of dinosaurs and pterosaurs
Adaptive radiation of birds and mammals
Extinction of ammonites, plesiosaurs, ichthyosaurs
Rise of woody angiosperms, snakes; first placental mammals (Eutheria) ...
extinction 1. The irrevocable elimination of species; can be a normal process of the natural world as species out-compete or kill off others or as environmental conditions change. 2.
Extinction is the ultimate fate of all species. The reasons for extinction are numerous.
The extinction of the Neanderthals is a perennially fascinating question for all human beings, because it's the best example we have of a resident group of distinctive hominids-a separate species, ...
MOLAR EXTINCTION COEFFICIENT
The molar extinction coefficient (e) of a species is defined by the equation A = ebc, where A is the absorbance of the solution, b is the path length, and c is the concentration of the species.
Eventual extinction of a natural species as massive pollen flow occurs from another related species and the older crop becomes more like the new crop. See Gene flow. Genetic code.
Gradual failure of health, strength, soundness, prosperity, or of any species of excellence or perfection; tendency toward dissolution or extinction; corruption; rottenness; decline; deterioration; as, the decay of the body; ...
A species that is in danger of extinction throughout all or a significant portion of its range.
endemic species
Species that are confined to a specific, relatively small geographic area.
The first mass extinction ended that period, but during the Cambrian Period which followed, an explosion of new forms began the evolutionary radiation that produced most of the major groups, or phyla, known today.
Genetic assimilation. Eventual extinction of a natural species as massive pollen flow occurs from another related species and the older crop becomes more like the new crop. See Gene flow.
They were killed off millions of years ago, and that extinction allowed the rise of mammals and birds. What makes reptiles so special? Dry skin.
The absorbance spectrum of tyrosine will be shown later; the extinction of tyrosine is only about 1/5 that of tryptophan at 280 nm, ...
Proteins encoded by genes residing in the MHC region are responsible for helping the body defend itself against microscopic invaders by distinguishing normal body constituents ("self") from everything else, which it then marks for extinction.
endangered species - species of animal or plant threatened with extinction as determined by the Environmental Protection Agency ...
Endangered: A species or ecosystem that is so reduced or delicate that it is threatened with or on the verge of extinction. Compare extinct, extirpated, threatened, vulnerable.
Looking through the ocular and without a specimen on the stage, turn the polarizer until the field of view becomes as dark as possible ("extinction").
 See also: Species, Organ, Plant, Animal, Animals
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