''Charniodiscus'' is an

Ediacaran The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and th ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

that in life was probably a stationary filter feeder that lived anchored to a sandy sea bed. The organism had a holdfast, stalk and frond. The holdfast was bulbous shaped, and the stalk was flexible. The frond was segmented and had a pointed tip. There were two growth forms: one with a short stem and a wide frond, and another with a long stalk, elevating a smaller frond about above the holdfast. While the organism superficially resembles the

sea pen Sea pens are colonial marine cnidarians belonging to the order Pennatulacea. There are 14 families within the order; 35 extant genera, and it is estimated that of 450 described species, around 200 are valid. Sea pens have a co ...

s (

cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that th ...

), it is probably not a

crown-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

animal. ''Charniodiscus'' was first found in

Charnwood Forest Charnwood Forest is a hilly tract in north-western Leicestershire, England, bounded by Leicester, Loughborough and Coalville. The area is undulating, rocky and picturesque, with barren areas. It also has some extensive tracts of woodland; i ...

in England, and named by Trevor D. Ford in 1958. The name is derived from the fact that Ford described a holdfast consisting only of a double concentric circle, his species being named ''Charniodiscus concentricus''. Later it was discovered that a frond (''Charnia masoni'') was part of a closely related organism. ''

Charnia ''Charnia'' is a genus of frond-like lifeforms belonging to the Ediacaran biota with segmented, leaf-like ridges branching alternately to the right and left from a zig-zag medial suture (thus exhibiting glide reflection, or opposite isometry). T ...

'' differs in the branching structure in the frond. ''Charniodiscus'' specimens are known from across the globe dating to around . Species are distinguished by the number of segments, the presence or absence of distal spines, and by shape ratios. Other described species, ''C. arboreus'', ''C. longus'', ''C. oppositus'', and ''C. spinosus'' are later considered to belong to own genus ''Arborea'', which is once considered as synonymous with ''Charniodiscus''. Status of ''C. yorgensis'' needs restudy.

References

*Glaessner, M. F., and Daily, B. (1959
"The Geology and Late Precambrian Fauna of the Ediacara Fossil Reserve"
''Records of the South Australian Museum'' 13: 369-407 retrieved 26 January 2008

External links

{{Taxonbar, from=Q2318754 Ediacaran life Enigmatic prehistoric animal genera Ediacaran Europe White Sea fossils

See also

References

External links