Trigonioidea
| Trigonioidea | ||||||||||
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Scaphotrigonia navis , Lower to Middle Jurassic |
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Trigonioidea | ||||||||||
| Lamarck , 1819 |
The Trigonioidea are the only superfamily of the order Trigonioida within the palaeoheterodont mussels . Most of the species are only known to be fossil . The first representatives of the superfamily appeared in the late Silurian .
characterization
The case is roughly triangular with a short rear end. The two flaps are approximately the same. The vortex clearly protrudes over the body of the case. The thick aragonitic shell has an outer prismatic layer and an inner pearly layer. The outside is smooth to heavily ribbed. The lock has a large, triangular cardinal tooth in the left flap and an articulated cardinal tooth in the right flap (schizodontic lock). There are no lateral teeth. The ligament is external and quite short. The sphincters are about the same size (isomyar), the pallial line is entire. The gills are filibranchiat .
evolution
The first Trigonioida appear as early as the late Silurian and quickly formed a large number of species (diversity). The various evolutionary lines are placed in several families. The height of development and diversity is reached in the Jura and Chalk . At the Cretaceous-Tertiary border , almost all lines died out until those that led to the recent genus Neotrigonia .
Systematics
- Order Trigonoida Dall , 1889
- Superfamily Trigonioidea Lamarck , 1819
- Family Trigoniidae Lamarck , 1819
- Family Eoschizodidae Newell & Boyd, 1975
- Family Schizodidae Newell & Boyd, 1975
- Family Costatoriidae Newell & Boyd, 1975
- Family Myophoriidae Bronn , 1849
- Family Minetrigoniidae Kobayashi , 1954
- Family Eoastartidae Newell & Boyd, 1975
- Family Scaphellinidae Newell & Ciriacks, 1962
- - Family Trigonioididae Cox , 1952
- Superfamily Trigonioidea Lamarck , 1819
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 . Zoological Journal of the Linnean Society, 148: 223-235, London 2006.
- V. Millard: Classification of Mollusca: A classification of world wide Mollusca . 544 pp., Victor Millard. South Africa 1997 ISBN 0-620-21261-6 .