Dapedium

Dapedium (from Greek: δαπέδων dapédon, 'pavement')[1] is an extinct genus of primitive neopterygian ray-finned 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 lived in the late Triassic and Jurassic periods.[2]

Dapedium
Temporal range:
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: †Dapediiformes
Family: †Dapediidae
Genus: †Dapedium
Leach, 1822
Species
  • †D. ballei
  • †D. caelatum
  • †D. granulatum
  • †D. noricum
  • †D. pholidotum
  • †D. politum
  • †D. punctatum

Appearance

The various species of Dapedium ranged from 9 to 40 centimetres (3.5 to 15.7 in) long, and all had an oval to near-circular body. The skin was covered with thick, rhomboid, ganoid (enamel-like) scales. The smallest species so far found is D. noricum.

Dapedium politum specimen from Oxford University Museum of Natural History

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 fins, along with the extended dorsal and anal fins formed a functional unit with the tail.[3] The tail was short and stout, providing the power for a sudden change in direction while the fish was swimming.

Dapedium pholidotum from Louis Agassiz collection at the Musée d'histoire naturelle de Neuchâtel

The upper jaw of Dapedium was moveable and could protrude from the mouth, enabling a wider gape to capture larger prey.

Distribution
D. pholidotum at the American Museum of Natural History.

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.

Behaviour

The strong and pointed dentition suggests that Dapedium was durophagous, feeding on hard-shelled invertebrates, like mussels and sea urchins.[3]

References
  1. Roberts, George (1839). An etymological and explanatory dictionary of the terms and language of geology. London: Longman, Orme, Brown, Green, & Longmans. p. 45. Retrieved 31 December 2021.
  2. Detlev Thies; Jens Waschkewitz (2016). "Redescription of Dapedium pholidotum (Agassiz, 1832) (Actinopterygii, Neopterygii) from the Lower Jurassic Posidonia Shale, with comments on the phylogenetic position of Dapedium Leach, 1822". Journal of Systematic Palaeontology. 14 (4): 339–364. doi:10.1080/14772019.2015.1043361. S2CID 130282395.
  3. Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 37. ISBN 1-84028-152-9.
  • 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


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