Cosmochlaina

Cosmochlaina Temporal range: Late Silurian to Early Devonian PreЄ Є O S D C P T J K Pg N
Cuticle of Cosmochlaina, retrieved from the Burgsvik beds by acid maceration. Cells about 12 μm in diameter.
Scientific classification
Kingdom:	Plantae (?)
Phylum:	Nematophyta
Class:	†Nematophytina
Order:	†Nematophytales
Family:	†Nematothalaceae Strother 1993
Genus:	Cosmochlaina Edwards 1986
Species
C. verruculosus (May be a typo, in Taylor 1988) C. verrucosa (Type) C. maculata C. physema C. Versiformis (All defined by Edwards 1986)

Cosmochlaina (from Greek: kosmos=ornament; xlaina=wrapper/cloak) is a form genus of nematophyte – an early (Siluran – Devonian) plant known only from fossil cuticles,^[1] often found in association with tubular structures.^[2] Where Nematothallus is sometimes used to relate only to tube-like structures, Cosmochlaina refers to the cuticle fragments. The form genus was put forwards by Dianne Edwards, and is diagnosed by inwards-pointing flanges and randomly oriented pseudo-cellular units.^[3] 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.^[3] The holes in the cuticle are often covered by round flaps, loosely attached along a side.^[3]

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.^[4] However, the status of this form genus in any one kingdom is not secure; members could, for example, represent arthropod cuticle.^[5] Alternatively, different species may in fact represent different parts of the same organism.^[3]

See also

• Nematothallus, a closely related sister taxon
• Evolutionary history of plants

References

1. ^ Kenrick, P.; Crane, P.R. (1997). "The origin and early evolution of plants on land". Nature 389 (6646): 33–39. Bibcode 1997Natur.389...33K. doi:10.1038/37918. 
2. ^ Gensel, P.G.; Johnson, N.G.; Strother, P.K. (1990). "Early Land Plant Debris (Hooker's" Waifs and Strays"?)". PALAIOS 5 (6): 520–547. doi:10.2307/3514860. JSTOR 3514860. 
3. ^ ^{a b c d} Edwards, D. (1986). "Dispersed cuticles of putative non-vascular plants from the Lower Devonian of Britain". Botanical journal of the Linnean Society 93 (3): 259–275. doi:10.1111/j.1095-8339.1982.tb01025.x. 
4. ^ Graham, L.E.; Wilcox, L.W.; Cook, M.E.; Gensel, P.G. (2004). "Resistant tissues of modern marchantioid liverworts resemble enigmatic Early Paleozoic microfossils". Proceedings of the National Academy of Sciences 101 (30): 11025–11029. Bibcode 2004PNAS..10111025G. doi:10.1073/pnas.0400484101. PMC 503736. PMID 15263095. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=503736. 
5. ^ Taylor, T.N. (1988). "The Origin of Land Plants: Some Answers, More Questions". Taxon 37 (4): 805–833. doi:10.2307/1222087. JSTOR 1222087.