Systematics - Systematics

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Systematics Phylogeny . There are more questions than answers in the phylogeny of the angiosperms. Part of  the problem lies in the lack of an adequate fossil record. The first clearly angiosperm fossil is from  the Early Cretaceous and is an impression of a fully developed flower. Molecular RNA/DNA  sequencing currently is being applied in new phylogenetic (cladistic) analyses to answer the question  of angiosperm origins. As yet, no generally accepted answer exists, but several hypothesis are being  hotly debated. The molecular data indicate the seed plants most closely related to the angiosperms  are the gnetophytes and bennettitaleans, which, incidentally, is the same conclusion reached by  some botanists using morphological and anatomical features 50 years ago. Others at the time  favored the “seed ferns” as angiosperm ancestors. A second debate revolves around the nature of 
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This note was uploaded on 11/14/2011 for the course BIO 1421 taught by Professor Farr during the Fall '08 term at Texas State.

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