Rudists
| Rudists | ||||||||||||
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Rudist Chalk, UAE |
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| Temporal occurrence | ||||||||||||
| Upper Jurassic to Chalk | ||||||||||||
| 161 to 65.5 million years | ||||||||||||
| Locations | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Hippuritoida | ||||||||||||
| Newell , 1965 |
The rudists (Hippuritoida) (from Latin rudus : rubble) are an extinct order of mussels (bivalvia) that belong to the subclass Heterodonta within this class. Rudists are characterized by strongly unevenly folded and mostly completely aberrant cases. They appear for the first time in the Upper Jura and die out on the Cretaceous-Paleogene border .
characterization
The housings of the typical rudists are unevenly hinged and one half of the housing is attached to the substrate or they lie on the sediment. The housings are goblet-like with a lid or spirally wound with a smaller "lid flap". The shells are usually extremely thick and often criss-crossed with longitudinal channels and cavities. The outer shell layer consists of the mineral calcite , while the inner layer is aragonitic . Due to the good conservation potential of calcite (compared to aragonite , which is much more soluble), the rudists have a very good fossil record; however, often only in a broken state in rubble limestone, hence the derivation of the name from the Latin term for rubble. The lock, originally heterodont, is heavily remodeled (pachydont) and has only one or two main teeth. The ligament is also greatly changed.
Way of life
Because of their sessile way of life in warm shallow water, it is assumed that they, like today's giant clams , lived in symbiosis with photosynthesis- promoting bacteria or algae.
In the Cretaceous period , rudists were very important as reef-building organisms. Due to their high porosity , the rocks that emerge from their shells can represent important oil storage rocks (for example in the rudist reefs on the Arabian Peninsula).
Systematics
The order Hippuritoida (Rudists) contains only the superfamily
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Hippuritoidea Gray, 1848 ("real" rudists). With the exception of the last family, the rudists are each attached to the substrate with the right flap.
- Diceratidae Dall, 1895
- Hippuritidae Gray, 1848
- Monopleuridae Munier-Chalmas, 1873
- Radiolitidae Gray, 1848
- Caprinidae d´Orbigny , 1850
- Polyconitidae Mac Gillavry, 1937
- Plagioptychidae Douvillé, 1888
- Ichthyosarcolitidae Douvillé, 1887
- Antillocaprinidae Mac Gillavry 1937
- Dictyoptychidae Skelton in Skelton & Benton, 1993
- Caprotinidae Gray, 1848
- Requieniidae Douvillé, 1919 (this family is attached to the substrate with the left flap).
Some authors also put the superfamily Megalodontoidea Morris & Lycett, 1853, into order.
literature
- Michael Amler, Rudolf Fischer & Nicole Rogalla: mussels (Haeckel library, volume 5). Enke Verlag, Stuttgart 2000 ISBN 3-13-118391-8 .
- Rüdiger Bieler & Paula M. Mikkelsen: Bivalvia. A look at the branches . In: Zoological Journal of the Linnean Society , Vol. 148 (2006), pp. 223-235, ISSN 0024-4082 .
- Peter W. Skelton & Andrew B. Smith: A preliminary phylogeny for rudist bivalves. Sifting clades grom grades . In: Elisabeth Harper, John D. Taylor & J. Alistair Crame (Eds.): The evolutionary Biology of the Bivalvia ( Geological Society of London Special Publications; Vol. 177). The Geological Press, London 2000, pp. 97-127, ISBN 1-86239-076-2 .
Web links
- Web Catalog of the Hippuritoidea (rudist bivalves) by Thomas Steuber (Taxonomy)
- Shells reveal how long a day earlier lasted by Jan Dönges (paleo-oceanography)
Individual evidence
- ↑ a b D. Schumann, T. Steubner: Rudists - Successful settlers and reef builders of the Cretaceous period . In: F. Steininger, D. Maronde (Hrsg.): Cities under water, Small Senckenberg series . No. 24 . Waldemar Kramer Verlag, Frankfurt am Main 1997, ISBN 3-7829-1148-2 , p. 117-122 .