Scenella
Encyclopedia
Scenella is an extinct genus
generally classified as a mollusc; it has been aligned with the gastropods, monoplacophora
ns, and helcionellids, although a firm association with either class has not been established. An affinity with the hydrozoa (as a flotation device) has been considered, although some authors oppose this hypothesis. A gastropod affinity is defended on the basis of six pairs of internal muscle scars, whilst the serially-repeated nature of these scars suggests to other authors a monoplacophoran affinity. However the specimens showing this scarring have not been convincingly shown to belong to the genus Scenella. A similarity to the Ediacaran Ovatoscutum
has also been drawn.
to the Ordovician
. Its remains have been found in Antarctica, Asia
, Europe
, and North America
. Individual fossils are common throughout the Burgess shale
, where they often occur in dense aggregations. Where they overlap, specimens deform as by draping. Specimens are sometimes cracked or torn, with margins often damaged by folding or "tattering".
Scenella is the only genus in the family Scenellidae. This family has no subfamilies and Scenella is the type genus
of the family Scenellidae.
The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005
categorizes Scenellidae in the superfamilia Scenelloidea
within the Paleozoic molluscs of uncertain systematic position.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
generally classified as a mollusc; it has been aligned with the gastropods, monoplacophora
Monoplacophora
Monoplacophora, meaning "bearing one plate", is a polyphyletic class of mollusks with a cap-like shell, living on the bottom of deep sea. Extant representatives were unknown until 1952; previously they were known only from the fossil record.- Definition :...
ns, and helcionellids, although a firm association with either class has not been established. An affinity with the hydrozoa (as a flotation device) has been considered, although some authors oppose this hypothesis. A gastropod affinity is defended on the basis of six pairs of internal muscle scars, whilst the serially-repeated nature of these scars suggests to other authors a monoplacophoran affinity. However the specimens showing this scarring have not been convincingly shown to belong to the genus Scenella. A similarity to the Ediacaran Ovatoscutum
Ovatoscutum
Ovatoscutum is one of many enigmatic organism known from Ediacaran deposites of the Flinders Ranges, Australia and the White Sea area, Russia. This genera contains one species, Ovatoscutum concentricium....
has also been drawn.
Description
Scenella is elongated along its anterior-posterior axis, and comprises concentric rings around a conical central peak. Radial and concentric corrugations exist in some species. Some specimens are preserved as organic films, others appear to have been infilled with calcite. They are usually preserved point-upwards, with their long axes consistently oriented; this probably represents their most stable position under their depositional current. Soft parts have never been reported in association with Scenella, suggesting that the preserved fragments separated quickly from the associated tissue prior to burial.Fossil occurrence
Scenella lived from the CambrianCambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
to the Ordovician
Ordovician
The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...
. Its remains have been found in Antarctica, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Individual fossils are common throughout the Burgess shale
Burgess Shale
The Burgess Shale Formation, located in the Canadian Rockies of British Columbia, is one of the world's most celebrated fossil fields, and the best of its kind. It is famous for the exceptional preservation of the soft parts of its fossils...
, where they often occur in dense aggregations. Where they overlap, specimens deform as by draping. Specimens are sometimes cracked or torn, with margins often damaged by folding or "tattering".
Taxonomy
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
of the family Scenellidae.
The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005
Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)
The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...
categorizes Scenellidae in the superfamilia Scenelloidea
Scenelloidea
Scenelloidea is an extinct superfamily of paleozoic molluscs of uncertain position .- Families :Based on the taxonomy of the Gastropoda by Bouchet & Rocroi families in the Scenelloidea include:* † Scenellidae...
within the Paleozoic molluscs of uncertain systematic position.
Species
Species in the genus Scenella include:| Species | Authority | Range |
|---|---|---|
| Scenella affinis | Ulrich and Schfield, 1897 | |
| Scenella amii | (Matthew, 1902) Babcock and Robinson 1988 | Burgess Shale (Mid Cambrian) |
| Scenella anomala | (Billings, 1865) Wagner 2008 | |
| Scenella augusta | (Billings, 1865) Wagner 2008 | |
| Scenella barrandei | (Linnarsson, 1879) (Bergerg-Madsen and Peel, 1986) | |
| Scenella beloitensis | Ulrich and Scofield (1897) | |
| Scenella clotho | Walcott, 1936 | |
| Scenella compressa | Ulrich and Scofield (1897) | |
| Scenella conica | Whiteaves, 1884 | |
| Scenella conula | (Walcott, 1884) | |
| Scenella conicum | (Whitfield, 1886) Ulrich and Scofield (1897) | |
| Scenella hujingtanensis | Yu, 1979 | |
| Scenella magnifica | Ulrich and Scofield (1897) | |
| S.? mira | Vasil’yeva, 1994 | |
| Scenella montrealensis | Billings (1865) | |
| Scenella obtusa | (Sardeson, 1892) Ulrich and Scofield (1897) | |
| Scenella orithyia | (Billings, 1865) Ulrich and Scofield (1897) | |
| Scenella pretensa | Raymond, 1905 | |
| Scenella radialis | Ulrich and Scofield (1897) | |
| Scenella radians | Babcock & Robinson | |
| Scenella radiata | Yu, 1979 | |
| Scenella reticulata | (Billings, 1872) (type) Image | |
| Scenella retusa | (Ford, 1873) | |
| Scenella unicarinata | (Kobayashi, 1934) Wagner 2008 | |
| Scenella varians | Walcott 1908 | |
| Scenella venillia | (Billings, 1865) Wagner 2008 | |
| Scenella tenuistriata Scenella tenuistriata Scenella tenuistriata is an extinct species generally classified as a mollusc or hydrozoan in the family Scenellidae.- Description :Scenella tenuistriata was originally discovered and described by Australian palaeontologist Frederick Chapman in 1911.Chapman's original text reads as follows:-... |
Chapman Frederick Chapman Frederick Chapman was the inaugural Australian Commonwealth Palaeontologist.-Early life:Chapman was born in Camden Town, London, England and studied at Royal College of Science, London where he was initially an assistant to John Wesley Judd... , 1911 |
Mid Cambrian |
External links
- Scenella at the Field Museum's Evolving Planet