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''Cosmochlaina'' (from Greek: kosmos=ornament; xlaina=wrapper/cloak) is a
form genus Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of s ...
of
nematophyte The Nematophyta or nematophytes are a paraphyletic group of land organisms, probably including some plants as well as algae known only from the fossil record, from the Silurian period until the early Devonian Rhynie chert. The type genus ''Nem ...
– an early (Silurian – Devonian) plant known only from fossil cuticles, often found in association with tubular structures. The form genus was put forwards by Dianne Edwards, and is diagnosed by inwards-pointing flanges and randomly oriented pseudo-cellular units. Projections on the outer surface are always present, and sometimes also appear on the inner surface; however, the surface of the cuticle itself is always smooth. The holes in the cuticle are often covered by round flaps, loosely attached along a side. Where ''Nematothallus'' was sometimes used to relate only to tube-like structures, ''Cosmochlaina'' was used in reference to the cuticle fragments. Material discovered later revealed its internal anatomy, which comprises a lichen-like mat of 'hyphae'. It has been suggested that the pores of'' Cosmochlaina ''represent broken-off rhizoids, on the basis that rotting and acid treatment of extant liverworts produces a similar perforated texture. However, the status of this form genus in any one kingdom is not secure; members could, for example, represent arthropod cuticle. Alternatively, different species may in fact represent different parts of the same organism. Based on the more recent material, a lichen affinity seems most plausible.


See also

*''
Nematothallus ''Nematothallus'' is a form genus comprising cuticle-like fossils. Some of its constituents likely represent red algae, whereas others resemble lichens. History of research ''Nematothallus'' was first described by Lang in 1937, who envision ...
'', a closely related sister taxon * Evolutionary history of plants


References

{{Taxonbar, from=Q10261156 Silurian plants Devonian plants