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User:TonySidaway/Evolution (view source)
Revision as of 19:16, September 7, 2012
, 19:16, September 7, 2012→Common descent: Extince species that seemed to be related to living species
==Common descent==
==Common descent==
Very close similarities between species have always been observed. Specific details of living organisms serve quite different purposes, such as the jaw bones of certain fish, whose analogues in mammals are part of the inner ear. The presumption of a familial relation existed long before plausible mechanisms were understood and confirmed. Organized taxonomies, based on such homologous traits, drew attention to this persuasive though at the time mysterious evidence suggesting common descent.
Very close similarities between species have always been observed. Specific details of living organisms serve quite different purposes, such as the jaw bones of certain fish, whose analogues in mammals are part of the inner ear. The presumption of a familial relation existed long before plausible mechanisms were understood and confirmed. Organized taxonomies, based on such homologous traits, drew attention to this persuasive though at the time mysterious evidence suggesting common descent.
By the early nineteenth century fossil collecting had spread widely enough to make the recognition of a succession of different forms of life to be a commonplace. Many noticed that some of the fossils seemed to be extinct members of known species, though often of different size from any of their living relatives, or bearing characteristics unknown in the surviving species.