With a sketchy fossil record, bryophyte phylogeny is based primarily on molecular sequencing of rRNA and morphology of extant species—with hypotheses changing as new data accumulate. Researchers generally believe that the charophyte‐coleochaete group of the green algae gave rise to the plants and that the bryophytes diverged from the common ancestor to vascular plants sometime during the Silurian, over 430 million years ago. Opinions differ concerning phylogenies within the bryophyte group, however. One view believes the three bryophyte groups had separate evolutionary origins and that only the mosses are more closely related to the plants. The bryophytes seem to have evolved during a time in which gametophyte characteristics were important for plant survival, whereas the vascular plants evolved when conditions favored the sporophyte portion of the life cycle.