Question

Name the common ancestor of mosses and tracheophytes

Answer 1

One hypothesis of the origin of the first land plants has an algal ancestor developing isomorphic alternation of generations (both generations are roughly the same size and shape) and dichotomous branching. The diploid sporophytes and the haploid gametophyte would look very much alike. This ancestor would diverge to produce an ancestor to the bryophytes and an ancestor to the seedless tracheophytes. Bryophytes could have developed by the gametophyte becoming the dominant generation and the sporophyte being retained as a "captive" plant dependent upon the gametophyte. Seedless tracheophytes could have developed from the same common ancestor by the reduction in size of the gametophyte generation relative to the sporophyte generation. Cooksonia is the oldest known fossil plant.