Anthocerotophyta, Bryophyta, Marchantiophyta. Lycopodiophyta, Pteridophyta, Pteridospermatophyta, Pinophyta, Cycadophyta, Ginkgophyta, Gnetophyta and Anthophyta.

Because ferns (Pteridophyta) and gymnosperms are part of the larger category of vascular plants (Tracheophyta) and share common features that mosses lack.

Perhaps also because of the spurious notion that "seed ferns" (Pteridospermatophyta), the ancestors of the gymnosperms, evolved from ferns. In fact, "seed ferns" are a large, heterogeneous category of plants which are generally believed to be only distantly related to true ferns.

"Glossopteris (Greek glossa, meaning "tongue", because the leaves were tongue-shaped) is the largest and best-known genus of the extinct order of seed ferns known as Glossopteridales (or in some cases as Arberiales or Dictyopteridiales). Long considered a fern after its discovery in 1824, it was later assigned to the gymnosperms. The genus is placed in the division Pteridospermatophyta. In reality, many of the plant groups included within this division are only distantly related to one another." That was straight out of the Wikipedia article. It explains what glossopteris is (or was), and a fossil of one of these long-gone plants would be what was asked about in the original question. A link is provided to our friends at Wikipedia for further information.