Tuesday, 17 December 2013

Coccosteus cuspidatus

Coccosteus is an extinct genus of arthrodire placoderm; placoderms were a class of armoured prehistoric fish. Their fossils have been discovered throughout Europe and across North America. Fossils of Coccosteus are very common in the Sandwick Fish Bed’s of Scotland. Only two known species are attributed to Coccosteus including; cuspidatus and decipiens. The head was covered with a regular number of bony plates and the body of these fish were long and slender ending in a narrow tail. This genus could grow to lengths of around 40 cm (almost 16 inches).

What Coccosteus lacked in size it made up for with its mouth. It had an internal joint between its neck vertebrae and the back of the skull, allowing the mouth to be opened even wider, this allowed Coccosteus to feed on fairly large prey. All arthrodires had bony dental plates in their jaws; these plates formed a sharp ‘beak’. The beak in arthrodires has often been falsely identified as ‘true teeth’, where in actual fact the beak is a result of the dental plates grinding against one another, thus keeping the beak sharp.

Coccosteus cuspidatus
Miller ex Agassiz, 1841
Meaning of generic name
Seed Bone-y

[Seed-Bone as a noun would have been kokkosteon in Greek.]
Meaning of specific name
Length: 25-40 cm
Complete specimens

[Complete with soft tissue or just complete with skeleta and outer bone parts ?]
Age and Distribution
Achanarras Horizon, Middle Old Red Sandstone, Sandwick Fish Bed's, Scotland, Middle Devonian, (Eifelian-Givetian).
Placodermi Arthrodira Coccosteoidea Coccosteidae
Further Reading
I.-Homosteus, Asmuss, compared with Coccosteus, Agassiz. Dr R. H. Traquair. Geological Magazine (Decade III), Volume 6, Issue 01, January 1889, pp 1-8 Published Online by Cambridge University Press 01 May 2009
Image by Nobu Tamura (click to enlarge)
Coccosteus cuspidatus, August 11, 2007:

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