Extinction psychology Extinction is observed in both operantly conditioned and classically conditioned behavior When operant behavior that has been previously reinforced no longer produces reinforcing consequences the behavior gradually stops occurring In classical conditioning, when a conditioned stimulus is presented alone, so that it no longer predicts the coming of the unconditioned stimulus, conditioned New fossil evidence supports theory that first mass The event, known as the end Ediacaran extinction, took place million years ago The earliest life on Earth consisted of microbes various types of single celled organisms. Extinction In ecology, extinction is often used informally to refer to local extinction, in which a species ceases to exist in the chosen area of study, but may still exist elsewhere.This phenomenon is also known as extirpation Local extinctions may be followed by a replacement of the species taken from other locations wolf reintroduction is an example of this. Men nearly caused human extinction , years ago, new News Corp is a network of leading companies in the world of diversified media, news, and information services. Alliance for Zero Extinction The Alliance for Zero Extinction AZE is a joint initiative of biodiversity conservation organizations from around the world to prevent extinctions by identifying and safeguarding key sites, which are the last remaining refuges of one or Endangered or Critically Endangered species. RAMAS Software by Applied Biomathematics RAMAS software delivers quantitative risk analysis for agriculture, conservation, engineering, and human health. The Watchman s Rattle A Radical New Theory of Collapse Buy The Watchman s Rattle A Radical New Theory of Collapse on FREE SHIPPING on qualified orders Thermal Engineer Claims Supernova Theory Explains Global In recent years, mass die offs of large animals like the sudden deaths of , endangered antelopes within a matter of weeks have been described as mysterious and remain largely unexplained Determining the cause of the retreat to ice ages and the abrupt warmings that spawned the K T extinction Overview Facts Britannica K T extinction, abbreviation of Cretaceous Tertiary extinction, also called K Pg extinction or Cretaceous Paleogene extinction, a global extinction event responsible for eliminating approximately percent of all species of animals at or very close to the boundary between the Cretaceous and Paleogene periods, about million years ago.The K T extinction was characterized by the Theory Definition of Theory by Merriam Webster Choose the Right Synonym for theory hypothesis, theory, law mean a formula derived by inference from scientific data that explains a principle operating in nature hypothesis implies insufficient evidence to provide than a tentative explanation a hypothesis explaining the extinction of the dinosaurs theory implies a greater range of evidence and greater likelihood of truth.