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The numbers of species cited above follows Frost and the total number of known (living) amphibian species as of March 31, 2019, is exactly 8,000, [12] of which nearly 90% are frogs. [ 13 ] With the phylogenetic classification, the taxon Labyrinthodontia has been discarded as it is a polyparaphyletic group without unique defining features apart ...
In 2006, of 4,035 species of amphibians that depend on water during some lifecycle stage, 1,356 (33.6%) were considered to be threatened. This is likely to be an underestimate because it excludes 1,427 species for which evidence was insufficient to assess their status. [201] Frog populations have declined dramatically since the 1950s.
Polyploid speciation, which involves changes in chromosome number, is a more common phenomenon, especially in plant species. Polyploidy is a mechanism that has caused many rapid speciation events in sympatry because offspring of, for example, tetraploid x diploid matings often result in triploid sterile progeny. [257]
This species, described by Cope in 1882, is by far the most common and well-described member of the genus. D. magnicornis was the first species known from more than vertebrae, and it allowed Cope and other paleontologists to realize the nature of Diplocaulus as a bizarre long-horned "batrachian" (amphibian). [11]
More than 99 percent of all species, amounting to over five billion species, [7] that ever lived on Earth are estimated to be extinct. [8] [9] Estimates on the number of Earth's current species range from 10 million to 14 million, [10] of which about 1.2 million have been documented and over 86 percent have not yet been described. [11]
This is a checklist of amphibians found in Northern America, based mainly on publications by the Society for the Study of Amphibians and Reptiles. [1] [2] [3] The information about range and status of almost all of these species can be found also for example in the IUCN Red List of Threatened Species site. [4]
The world’s frogs, salamanders, newts and other amphibians remain in serious trouble. A new global assessment has found that 41% of amphibian species that scientists have studied are threatened ...
The common descent of organisms was first deduced from four simple facts about organisms: First, they have geographic distributions that cannot be explained by local adaptation. Second, the diversity of life is not a set of unique organisms, but organisms that share morphological similarities .