''Somatohelix'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

organism of uncertain affinities from the late

Ediacaran The Ediacaran ( ) is a geological period of the Neoproterozoic geologic era, Era that spans 96 million years from the end of the Cryogenian Period at 635 Million years ago, Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last ...

of the

Flinders Ranges The Flinders Ranges are the largest mountain ranges in South Australia, which starts about north of Adelaide. The ranges stretch for over from Port Pirie to Lake Callabonna. The Adnyamathanha people are the Aboriginal group who have inhab ...

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...

. Originally interpreted as a trace fossil, better preserved material was found which confirmed it was not a trace fossil. It is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus, containing only ''Somatohelix sinuosus''.

Discovery and naming

The original material of ''Somatohelix'' was found in the Ediacara Member of the Rawnsley Quartzite, in

Nilpena Ediacara National Park __NOTOC__ Nilpena Ediacara National Park, which includes the former Ediacara Conservation Park, is a protected area located in the northern Flinders Ranges, in the state of South Australia. It is located about around north of Adelaide city cent ...

South Australia in 1969 and informally listed under 'Form E' and 'Form F', but with the discovery of new material, were formally described and named in 2011. The generic name ''Somatohelix'' is derived from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

words ''soma'', to mean "body"; and ''helix'', to mean "helical/coiled", referring to the overall appearance of the fossil material. The specific name ''sinuosus'' is derived directly from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word ''sinuosus'', to mean "winding/sinuous", again referring to the appearance of the fossil material.

Description

''Somatohelix sinuosus'' is a curvilinear, spiralling tubular form, growing from in length, and with a width of . Where whole specimens are known, the terminal end, or base of the tubes, is typically rounded in appearance. As for the whole tube, the entire length has consistent diameter and is smooth, and was most likely soft as well, as evidenced by folds in the fossil material which formed upon felling and burial of the tubes. As for the

sinuosity Sinuosity, sinuosity index, or sinuosity coefficient of a continuously differentiable curve having at least one inflection point is the ratio of the curvilinear length (along the curve) and the Euclidean distance ( straight line) between th ...

of the tubes themselves, have an average value of 3.06, although there are out-liners within the smaller and larger specimens, which have smaller and larger wavelengths respectively. Accompanying 4 out of the 191 collected specimens is a circular feature at one end of the tube, with one specimen being fully attached to said tube, with the circles themselves being wrinkly in nature, and are preserved as positives and negatives.

Affinity

The affinities of ''Somatohelix'' remains unknown, but several comparisons have been made to other tubular forms. It has been compared to ''

Funisia ''Funisisa'' is a genus of extinct, colonial sponge-like organisms from the late Ediacaran of South Australia. It is a monotypic genus, containing only ''Funisisa dorothea''. Discovery and naming The fossil material of ''Funisia'' was found ...

'' in their modes of preservation, but the similarities end there, as ''Somatohelix'' does not have any serial partitions/divisions like ''Funisia'', nor does it branch, as seen in some ''Funisia'' specimens. Another comparison is with ''

Vendoconularia ''Vendoconularia'' is a genus of Ediacaran organism consisting of a hexagonal cone, which is thought to have housed a tentaculate organism. Three longitudinal bands are interspersed between the six sides of the cone. The discovery of vendoconula ...

'', which also has many similar preservational traits with ''Somatohelix'', like folding and curvature. Although folding within ''Vendoconularia'' specimens is much rarer than what is seen ''Somatohelix'', and does not have a consistent sinuosity like ''Somatohelix''. Alongside this, the widest specimen of ''Vendoconularia'' is , which is alot thinner than ''Somatohelix''. ''Vendoconularia'' is also preserved as carbonised, flattened tubes. It is also noted that modern analogues of organisms with a helical constructional morphology are found not only in disparate

Kingdoms Kingdom commonly refers to: * A monarchic state or realm ruled by a king or queen. ** A monarchic chiefdom, represented or governed by a king or queen. * Kingdom (biology), a category in biological taxonomy Kingdom may also refer to: Arts and me ...

, but also in multiple domains.

Cirrhipathes spiralis ''Cirrhipathes'' is a genus of black coral from the family Antipathidae. Coral species in this genus are commonly known as whip or wire corals because they often exhibit a twisted or coiled morphology. In addition to their colorful appearance, wi ...

is given as an example, which has a helical shape that is used to maximize its surface area.

References

{{Taxonbar, from=Q7559294 Ediacaran life Fossils of Australia

Discovery and naming

Description

Affinity

See also

References