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Temporal range: Early Devonian – Middle Devonian[1]
Scientific classification e
Kingdom: Plantae
Phylum: incertae sedis
Family: Spongiophytaceae
Genus: Spongiophyton
Kräusel, 1954
  • S. hirsutum
  • S. lenticulare Kräusel, 1954(type)
  • S. minutissimum Kräusel, 1954
  • S. nanum emend Chaloner et al, 1974

Spongiophyton was a thallose fossil of the early to mid Devonian, which is notoriously difficult to classify.

Spongiophyton displayed dichotomous branching, and a flattened/elliptical cross section with a thick (20–80 μm) upper cuticular surface.[2] It is also perforated with pores resembling those of some liverworts.[2] It probably grew on the banks of rivers.[3] Spongiophyton has been mistakenly interpreted as tree resin[4] and lycopod cuticle,[5] and was later identified as the cuticle of a thalloid plant.[6] It has most recently been interpreted on morphological[7] and isotopic[8] grounds as a lichen - which would make it the earliest known representative of this group.[9]

The significance of the isotopic data has, however, been called into question. Jahren et al. argued that mosses and liverworts had a δ13C signature of under −26‰, and lichens were exclusively > −26‰. But in deducing this they relied solely on their own data, neglecting to include published datasets or bryophytes from a wide range of habitats. They also failed to take into account any adjustment necessary to overcome post-burial alteration of the δ13C, or to compensate for the different isotopic composition of the early Devonian atmosphere.[2] Repeating Jahren's experiments with these factors taken into account shows that most major groups' δ13C values overlap significantly, and do not provide a statistically significant case for the inclusion of Spongiophyton in any group.[2]


  1. ^ Taylor, W. A.; Free, C.; Boyce, C.; Helgemo, R.; Ochoada, J. (2004). "SEM Analysis of Spongiophyton Interpreted as a Fossil Lichen". International Journal of Plant Sciences. 165: 875. doi:10.1086/422129. 
  2. ^ a b c d Fletcher (2004)
  3. ^ Gensel et al.. 1991; Griffing et al. 2000; in Fletcher (2004)
  4. ^ Penhallow (1889) in Fletcher (2004)
  5. ^ Barbosa (1949) in Fletcher (2004)
  6. ^ Kräusel (1954) in Fletcher (2004)
  7. ^ Taylor et al. (2004)
  8. ^ Jahren et al. (2003)
  9. ^ Retallack (1994) suggested that the Ediacaran biota were lichens, but has since refined this hypothesis (Retallack, 2007).