نتایج جستجو برای: mass extinction
تعداد نتایج: 500636 فیلتر نتایج به سال:
One of the most severe mass extinctions of the Phanerozoic, the Triassic-Jurassic event is greater or equal in magnitude to that at the more famous K-T boundary (Benton, 1994) (Fig. 1). Such severity, at least for marine families is also supported by Foote’s (2003) statistical revaluations, although there remain dissenters (e.g. Hallam, 2002; Lucas et al., 2002). The cause of this mass-extincti...
The gaps in the fossil record gave rise to the hypothesis that evolution proceeded in long periods of stasis, which alternated with occasional, rapid changes that yielded evolutionary progress. One mechanism that could cause these punctuated bursts is the recolonization of changing and deserted niches after mass extinction events. Furthermore, paleontological studies have shown that there is a ...
Although mass extinctions probably account for the disappearance of less than 5% of all extinct species, the evolutionary opportunities they have created have had a disproportionate effect on the history of life. Theoretical considerations and simulations have suggested that the empty niches created by a mass extinction should refill rapidly after extinction ameliorates. Under logistic models, ...
The discipline-wide effort to database the fossil record at the occurrence level has made it possible to estimate marine invertebrate extinction and origination rates with much greater accuracy. The new data show that two biotic mechanisms have hastened recoveries from mass extinctions and confined diversity to a relatively narrow range over the past 500 million years (Myr). First, a drop in di...
Given that 99.9% of species that have ever existed on the Earth are already extinct, the most effective approach to examining extinction over long time scales is to delve into the 3.7 billion year history of extinction preserved in the fossil record. The “discovery” of extinction, both as a philosophical concept and a biological reality, can be traced back to Baron Georges Cuvier and his studie...
The degree of biodiversity was dynamically changing during the centuries and millennia, according to available resources it was gradually growing. In the course of evolution the periods of intensive speciation and relative “speciation rest“ were alternating, with five major episodes of mass extinction (Wilson, 1989; Raup, 1992). The worst extinction event took place at the end of the Permian pe...
Extinction risk in vertebrates has been linked to large body size, but this putative relationship has only been explored for select taxa, with variable results. Using a newly assembled and taxonomically expansive database, we analyzed the relationships between extinction risk and body mass (27,647 species) and between extinction risk and range size (21,294 species) for vertebrates across six ma...
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