Volborthella
Encyclopedia
Volborthella is an animal of incertain classification, whose fossils pre-date . It has been considered for a period a cephalopod. However discoveries of more detailed fossils showed that Volborthella’s small, conical shell was not secreted but built from grains of the mineral silicon dioxide
(silica), and that it was not divided into a series of compartments by septa as those of fossil shelled cephalopods and the living Nautilus
are. This illusion was a result of the laminated texture of the organisms' tests. Therefore, Volborthella’s classification is now uncertain.
It has been speculated that it may in fact represent a sclerite of a larger organism, on the basis of one specimen; however, it may be premature to accept this hypothesis, as the arrangement of sclerites producing this impression may have been occurred by chance. The Ordovician scleritome-bearing Curviconophorus, as well as the Halwaxiids, lobopods and echinoderms, demonstrate the diversity of organisms which may produce a scleritome of this nature. The related Campitius was originally suggested to be part of a radula
rather than a scleritome.
Volborthella is widespread, and a useful biostratigraphic indicator; it has been found in North America, Greenland, Spitsbergen, and northeastern Europe, and is restricted to Lower Cambrian rocks, appearing before the trilobites and co-existing with them for some time.
Volborthella has been described as a 'failed attempt in mineralisation'; it constructed its wall by agglutinating grains of sediment, much like some foramanifera, and declined in conjunction with the origin of truly-biomineralising organisms. However, its similarity to Salterella
, which contained embedded sediment grains in its mineralised wall, suggests a possible biological relationship - Salterella may have begun to mineraluse its agglutinated wall. Some Volborthella specimens do show taphonomic hints that some form of lightly mineralised sheath may have enclosed its agglutinated shell.
Silicon dioxide
The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with the chemical formula '. It has been known for its hardness since antiquity...
(silica), and that it was not divided into a series of compartments by septa as those of fossil shelled cephalopods and the living Nautilus
Nautilus
Nautilus is the common name of marine creatures of cephalopod family Nautilidae, the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in two genera, the type of which is the genus Nautilus...
are. This illusion was a result of the laminated texture of the organisms' tests. Therefore, Volborthella’s classification is now uncertain.
It has been speculated that it may in fact represent a sclerite of a larger organism, on the basis of one specimen; however, it may be premature to accept this hypothesis, as the arrangement of sclerites producing this impression may have been occurred by chance. The Ordovician scleritome-bearing Curviconophorus, as well as the Halwaxiids, lobopods and echinoderms, demonstrate the diversity of organisms which may produce a scleritome of this nature. The related Campitius was originally suggested to be part of a radula
Radula
The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...
rather than a scleritome.
Volborthella is widespread, and a useful biostratigraphic indicator; it has been found in North America, Greenland, Spitsbergen, and northeastern Europe, and is restricted to Lower Cambrian rocks, appearing before the trilobites and co-existing with them for some time.
Volborthella has been described as a 'failed attempt in mineralisation'; it constructed its wall by agglutinating grains of sediment, much like some foramanifera, and declined in conjunction with the origin of truly-biomineralising organisms. However, its similarity to Salterella
Salterella
Salterella is an enigmatic Cambrian–Ordovician genus with a calcareous shell that appears to be septate, but is rather filled with stratified laminar deposits. Its shell contains grains of sediment....
, which contained embedded sediment grains in its mineralised wall, suggests a possible biological relationship - Salterella may have begun to mineraluse its agglutinated wall. Some Volborthella specimens do show taphonomic hints that some form of lightly mineralised sheath may have enclosed its agglutinated shell.