Gemuendina
Gemuendina | ||||||||||||
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Fossil remains from Gemuendina stuertzi |
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Temporal occurrence | ||||||||||||
Emsium ( Lower Devonian ) | ||||||||||||
407.6 to 393.3 million years | ||||||||||||
Locations | ||||||||||||
Systematics | ||||||||||||
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Scientific name | ||||||||||||
Gemuendina | ||||||||||||
Traquair , 1903 |
Gemuendina was a plate skin who lived in the seas of the Lower Devonian . So far, specimens have only been found in Germany.
features
Much is known about Gemuendina because of the well-preserved fossils . It reached up to a foot in length, most of the specimens found are slightly smaller. The pectoral fins were broad and wing-shaped and strongly resembled those of the rays . The flattened body and the overhead eyes and nostrils are adaptations to life on the floor of a shallow sea , in this case the Rheno-Hercynian Ocean. The similarities of Gemuendina with today's rays, which only developed around 290 million years later from the Jurassic , have nothing to do with a closer relationship between these two groups of marine life. They are an expression of a convergent , analogous development due to the way of life in a similar living space.
Gemuendina had a mosaic-shaped shell made of plate bones. The head was armored with large bone plates, and there were other small plates on various parts of the body. The fins were unarmored. These disconnected bone plates were mostly scattered after the death of the plate skin. Therefore only a few complete specimens have been found so far. The rarity of such finds says nothing about the frequency of Gemuendina .
Most of the skeletal elements were made up of cartilage. Gemuendina had no teeth, but star-shaped bones on the jaws, which are called " tubercles ". The jaw plates could be pushed out of the mouth to grab the prey. Hard-shelled organisms such as sea urchins and mussels could also be crushed with the “tubercles” .
Location
The finds from Gemuendina come from the Lower Devonian slates of the Hunsrück . The Hunsrück schist is known for the fossils from the Devon Sea, which at that time stretched across Central Europe. The most important finds come from Bundenbach and Gemünden , the place after which Gemuendina was named. Fossil finds from Gemuendina can be seen in the Castle Park Museum in Bad Kreuznach in Rhineland-Palatinate . The specific epithet of the Gemuendina stuertzi type honors the geologist and paleontologist Bernhard Stürtz (1845–1928). The species was described by the Scottish paleontologist Ramsay Heatley Traquair in 1903.
Systematics
Gemuendina belonged to the group of Rhenanida , of which only four genera are known. Species of this genera are, in addition to Gemuendina stuertzi , Asterosteus stenocephalus , Jagorina pandora and Bolivosteus chacomensis . The Rhenanida are a sister group of the Antiarchi at the base of the Placodermi . Gemuendina is one of the oldest forms in this group.
literature
- Dorling Kindersley: Encyclopedia of Dinosaurs and Prehistoric Life . 2001, p. 45, ISBN 3-8310-0342-4
- Philippe Janvier: Early Vertebrates . Oxford University Press, 1998, ISBN 0-19-854047-7
- John A. Long: The Rise of Fishes: 500 Million Years of Evolution . The Johns Hopkins University Press, 1996, ISBN 0-8018-5438-5
swell
- Gemuendina
- Rhenanida near Palaeos
Individual evidence
- ^ Ramsay Heatley Traquair: The Lower Devonian Fishes of Gemunden. Transactions of The Royal Society of Edinburgh, 40, 723-739, 1903
Web links
- Reconstruction of Gemuendina stuertzi picture at Devonianlife