A REVIEW OF PERMINERALIZED EURAMERICAN CARBONIFEROUS TREE FERNS

Anatomically preserved vegetative and fertile features of the extinct fern family Psaroniaceae (Marattiales) are discussed. Lower Pennsylvan ian stem fossils are monocyclic distichous siphonosteles, whereas youn ger stems are polycyclic siphonosteles with a prominent root mantle. T he histology and phyllotaxis of stems are reliable characters when des cribed from the same level of the stems. Structurally preserved fertil e foliage is divided into 7 genera, of which 4 are monotypic, 2 ditypi c, and one contains 26 species. This disparity in species distribution is due to inconsistent generic circumscription. Some genera are circu mscribed by features of the synangium alone (Scolecopteris, Eoangiopte ris, Sturiella, Acaulangium), while others employ foliar, synangial, a nd spore characteristics (Grandeuryella, Acitheca, Araiangium). The fe rtile foliage Scolecopteris has 26 species divided into 4 groups (Alta , Latifolia, Minor, and Oliveri). Several of these informal species gr oups may be monophyletic and deserve generic status. Acaulangium is sh own to be distinct from Scolecopteris, and congeneric with Sturiella. Grandeuryella synangial attachment is similar to the extant marattiale an, Angiopteris, and is not clearly different from Acaulangium (Sturie lla). Spore-wall layering and ornamentation is discussed, and the prob lem of identifying characters of generic significance is addressed thr oughout this review.