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"Now, here, you see, it takes all the running you can do, to keep in the same place." — Lewis Carroll [4]. In 1973, Leigh Van Valen proposed the hypothesis as an "explanatory tangent" to explain the "law of extinction" known as "Van Valen's law", [1] which states that the probability of extinction does not depend on the lifetime of the species or higher-rank taxon, instead being constant ...
The annual life cycle has evolved in over 120 plant families across the entire angiosperm phylogeny. [213] Notably, the prevalence of annual species increases under hot-dry summer conditions in different families including Asteraceae, Brassicaceae, Fabaceae, and Poaceae. [212] Leaves have evolved multiple times - see Evolutionary history of plants.
Accelerando is a 2005 science fiction novel consisting of a series of interconnected short stories written by British author Charles Stross.As well as normal hardback and paperback editions, it was released as a free e-book under the CC BY-NC-ND license.
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
They’re awesome, but slapping a deep 4-point line on the court doesn’t solve the shot desert problem. (Grant Thomas/Yahoo Sports Illustration) So, we shorten the old 3-point arc.
An isodar, or habitat isodar, is a theory in evolutionary ecology developed in the late 1980s by Douglas W. Morris. [2] [3] Isodars model density-dependent habitat selection for one or two species in two habitats according to the ideal free and ideal despotic distributions.
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 ...
Birds evolved from other theropod dinosaurs that had already gone through a phase of size reduction during the Middle Jurassic, combined with rapid evolutionary changes. [3] Flying birds during their evolution further reduced relative weight through several characteristics such as the loss of teeth, shrinkage of the gonads out of mating season ...