Evolutionary criteria in thallophytes: a radical alternative.

The classical assumptions, upon which all previous phylogenies for the lower plants (Thallophytes) have been based, are claimed to be erroneous. An alternative view, that the eukaryotic cell arose in the late Precambrian from prokaryotic ancestors by a specific series of symbioses, is referred to here. Mutually consistent phylogenies, one for the prokaryotes, another for the lower eukaryotes, can be constructed on the basis of the symbiotic theory. The resulting prokaryote phylogeny is presented here; it is claimed to be more consistent with cytological data, measured DNA base ratios, and the fossil record than the several classical partial phylogenies for Thallophytes recently published.