Dapedium
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| Dapedium Fossil range: Late Triassic to Early Jurassic |
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D. caelatum |
Dapedium (aka Dapedius or Moonfish) is an extinct species of enamel-scaled fish. The first-described finding was an example of D. politum, found in the Lower Lias of Lyme Regis, on the Jurassic Coast of England (Leach 1822). Dapedium developed in the late Triassic and Jurassic periods (circa two hundred million years ago).
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[edit] Body
The body was fusiform to oval or near-circular. The skin was covered with thick, rhomboid, ganoid (enamel-like) scales. Depending upon species, the animal reached a length from 9 to 40 cm. The smallest species so far found is Dapedium noricum.
The skull was armoured with bony dermal plates, which were especially plentiful in the orbital region. These bones bore irregular tubercles. The small pectoral and pelvic (ventral) fins, along with the extended dorsal and pelvic fins formed a functional unit with the tail. The Dapedium was a primitive neopterygian ('new fins') species of fish. The neopterygians are more advanced than other ray-finned fish. The pelvic fins were located at the lowest point of the perimeter. The dorsal and pelvic fins were set back caudally. The tail was short and stout, providing the power for a sudden change in direction while the fish was swimming.
[edit] Biosphere
Dapedium lived mostly in the Jurassic seas of Europe, a peripheral continental shelf sea of the Tethys Ocean. Notable finds have been made in Holzmaden, Germany, in Temple Grafton, Warwickshire, England and in Lyme Regis, Dorset, England.
[edit] Behaviour
The strong and pointed dentition suggests that Dapedium fed on hard-shelled invertebrates, like mussels and sea urchins. The term for this type of feeding is durophagous. The upper jaw of a Dapedium was moveable and could protrude from the mouth, enabling a wider gape for larger prey.
[edit] References
- Detlev THIES & Annette HERZOG, New information on †Dapedium LEACH 1822 (Actinopterygii, †Semionotiformes), in Mesozoic Fishes 2 – Systematics and Fossil Record, G. Arratia & H.-P. Schultze (eds.): pp. 143-152, Verlag Dr. Friedrich Pfeil, München, Germany – ISBN 3-931516-48-2
- This article is based on a translation of an article from the German Wikipedia.
