Nematophytes †

Protosalvinia †

• Dawson, 1886

• Found in Late Devonian sediments, these fossils exhibit a thalloid appearance with short dichotomous branching. The branches in the largest species were as much as one centimeter across.

• Interpretations seem to narrow this organism to a photosynthetic plant, either a fossil liverwort or brown alga.

  • No definitive brown algae have been identified from before the Cenozoic era

  • Lignin and cutin have been found in the thallus, similar to plants and charophytes

  • Embedded in the tissues of the thallus are chambers in which spores (200 micrometre diameter) were produced by meiosis, similar to conceptacles

  • Spores show no features in common with living groups of brown algae, and have sporopollenin in the spore walls, similar to streptophytes

  • Diversity 

P. arnoldii

• Bharadwaj & Venkatachala, 1960

• Late Devonian of Kentucky

P. bilobata 

• Dawson, 1886

P. braziliensis

• Dawson, 1886

P. furcata 

• Arnold, 1954

P. huronensis 

• Dawson, 1886

P. punctata [type]

• (Newton) Dawson (1886)

P. ravenna 

• White & Stadnichenko, 1923

Parka decipiens †

• Miller, 1857

• Late Silurian-Early Devonian of Scotland 

• Compression fossils that are circular or elliptic in shape

• The form is 0.5-2.0 cm in diameter, showing a reticulated, mesh-like structure on the surface

• Small discs present in the meshes of the reticulum, which appear to be sporangia with 30K+ spores

• Some specimens show a radial pattern of striations and a "holdfast" in the center of the disk. These latter structures were probably involved in the attachment to the soil

• The systematic place of Parka is uncertain

  • Fossils resemble both extant liverworts and green algae, although chemical composition indicates a relationship with green algae

  • This was probably a group of early plant-algae organisms, which colonized near-shore, barren land

Nematothallus †

• Lang, 1937

• This form taxon is found in the Middle Silurian and the Early Devonian; 

• Nematothallus fossils resemble sheets of cells, such as the cuticle of a plant

• Fossils can appear as irregularly shaped black patches measuring 0.5 to 6 cm in diameter 

• It is not developed in the way of cell division in higher plants; therefore, it is called pseudoparenchymatous

  • Under the cuticle is a mat of thin threads or tubes, which vary in diameter (3-40 µm). Spores have also been found in the mats. 

• Some researchers have suggested an affinity with lichens or red algae

• Diversity 

N. pseudovasculosa

• Lang, 1937

• Lochkovian of the UK

N. radiata

• Lang, 1937

• Lochkovian of the UK

Spongiophyton †

• Kräusel, 1954

• Dichotomous branching, and a flattened/elliptical cross-section with a thick (20–80 μm) upper cuticular surface.

• It is also perforated with pores resembling those of some liverworts.

• Spongiophyton has been mistakenly interpreted as tree resin and lycopod cuticle, and was later identified as the cuticle of a thalloid plant.

• It has most recently been interpreted on morphological and isotopic grounds as a lichen (Taylor et al., 2004)

  • Spongiophyton is the earliest evidence of lichens, from the Early Devonian of Brazil (Becker-Kerber et al., 2025). 

  • This fossil had internal hyphae, algal cells, and possible reproductive structures, confirming that it was one of the oldest known fossilized lichens.

  • Spongiophyton abundance and wide paleo-geographic distribution in Devonian successions reveal an ecologically prominent presence of lichens during the late stages of terrestrial colonization

• Diversity 

S. articulatum

• Kräusel, 1954

• Early Devonian of Brazil

S. hirsutum

• Kräusel, 1954

• Early Devonian of Brazil

S. lenticulare

• Kräusel, 1954

S. minutissimum

• Kräusel, 1954

• Early Devonian of Brazil

S. nanum

• Kräusel, 1954

• Early Devonian of Brazil