''Chondroplon bilobatum'' is a medusoid

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 ...

. It has sand-filled tubes, although these may not have been sand-filled in life. It has a shield-like shape, with one end different from the other, and bilateral symmetry, and although it has been suggested that it possesses

glide reflection In 2-dimensional geometry, a glide reflection (or transflection) is a symmetry operation that consists of a reflection over a line and then translation along that line, combined into a single operation. The intermediate step between reflection ...

symmetry, such suggestions are based upon a taphonomic effect deforming some specimens. ''Chondroplon'' was originally described by

Mary Wade Mary Wade (17 December 1775 – 17 December 1859) was a British woman and convict who was transported to Australia when she was 13 years old. She was the youngest convict aboard , part of the Second Fleet. Her family grew to include five gener ...

in 1971 from fossils found in South Australia. It was named after

chondrophore The chondrophores or porpitids are a small group of hydrozoans in the family Porpitidae. Though it derives from an outdated name for this lineage (see below), some still find the term "chondrophore" useful as a synonym to "porpitid" in discussio ...

s — chitinous floats found on some kinds of colonial floating hydroids. In addition to the

Ediacara Hills Ediacara Hills are a range of low hills in the northern part of the Flinders Ranges of South Australia, around north of the state capital of Adelaide. The hills are known for being the location of significant fossils, and have given their nam ...

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

''Chondroplon'' is also found in the

White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is su ...

area of

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. The host rocks in these areas have been dated as 555 million years old. The original interpretation was that ''Chondroplon'' is a chondrophorine

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 ...

n. It has also been interpreted as a deformed

Dickinsonia ''Dickinsonia'' is an extinct genus of basal animal that lived during the late Ediacaran period in what is now Australia, China, Russia and Ukraine. The individual ''Dickinsonia'' typically resembles a bilaterally symmetrical ribbed oval. Its a ...

. The Vendobionta theory has them as ''"fluid–filled quilts"''. As with most of the

Ediacaran biota The Ediacaran (; formerly Vendian) biota is a Taxonomy (biology), taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period (). These were composed of enigmatic tubular and frond-sh ...

, scientists are yet to reach agreement on a firm classification for this enigmatic fossil.

References

Cnidarians White Sea fossils Proarticulata Ediacaran life Fossils of Russia Fossil taxa described in 1971 {{ediacaran-stub

See also

References