Coeloscleritophora
| Coeloscleritophora | ||||||
|---|---|---|---|---|---|---|
| Temporal occurrence | ||||||
| lower Cambrian to upper Cambrian | ||||||
| 542 to 516 million years | ||||||
| Locations | ||||||
|
Canada, United States, Greenland, England, France, Spain, China, Australia |
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| Systematics | ||||||
|
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| Scientific name | ||||||
| Coeloscleritophora | ||||||
| Bengtson & Missarzhevsky , 1981 |
The Coeloscleritophora are an extinct possibly polyphyletic class of the animal kingdom that lived during the Cambrian . Their taxonomic position is controversial.
Description and etymology
The characteristic feature of the animal class are the coelosclerites , which were hollow inside, consisted of aragonite and had a characteristic microstructure. Hence its scientific name, which can be reproduced as a coelosklerite bearer (from ancient Greek φóρος (phóros), bearing, bringing. Coelosklerite is derived from ancient Greek κοῖλος (koilos) hollow and σκληρός (sklēros) hard.
The skeleton of the Coeloscleritophora shows similarities with that of the mollusks and also the taxon Halkieria , which belongs to the class, shows great similarities with the beetle snails (Polyplacophora). The shells of molluscs and coeloscleritophora may have formed in a similar way. However, there are several reasons to doubt this purely external correspondence.
Occurrence
Coeloscleritophora are a common component within the SSF fauna community of the Lower Cambrian.
Taxonomy
The Coeloscleritophora are in turn made up of two families - the Chancelloriidae and the Halkieriidae . The families of the Sachitidae and the Siphogonuchitidae are also associated with the polyphyletic class. The Halkieriids include the taxa Halkieria and Wiwaxia . Allegedly, the fossil Ausia from the Ediacarium is supposed to occupy an intermediate position between the two families of the Chancelloriidae and the Halkieriidae.
literature
- Bengtson, S. and Missarzhevsky, VV: Coeloscleritophora - a major group of enigmatic Cambrian metazoans . In: USGS Open-File Report . Vol. 81-743, 1981, pp. 19-21 . (Digitized version)
- Conway Morris, S. and Chapman, A .: Lower Cambrian halkieriids and other coeloscleritophorans from Aksu-Wushi, Xinjiang, China . In: Journal of Paleontology . tape 71 , 1997, pp. 6-22 .
Individual evidence
- ↑ Porter, SM: Skeletal Microstructure Indicates Chancelloriids and Halkieriids Are Closely Related . In: Palaeontology . tape 51 (4) , 2008, pp. 865 , doi : 10.1111 / j.1475-4983.2008.00792.x .
- ↑ Bengtson, S .: The cap-shaped Cambrian fossil Maikhanella and the relationship between coeloscleritophorans and molluscs . In: Lethaia. 25 (4) . 1992, p. 401-420 , doi : 10.1111 / j.1502-3931.1992.tb01644.x .
- ^ Yochelson, EL: Molluscan affinity of coeloscleritophorans . In: Lethaia . tape 26 (1) , 1993, pp. 47-48 , doi : 10.1111 / j.1502-3931.1993.tb01509.x .
- ↑ Dzik, Jerzy: Possible Ediacaran Ancestry of the Halkieriids . In: Smith, Martin R., O'Brien, Lorna J. and Caron, Jean-Bernard (Eds.): Abstract Volume. International Conference on the Cambrian Explosion (Walcott 2009) . Toronto, Ontario, Canada: The Burgess Shale Consortium 2009, ISBN 978-0-9812885-1-2 .