Name: Cephalaspis‭ (‬Head shield‭).
Phonetic: Seff-ah-lass-pis.
Named By: Louis Agassiz‭ ‬-‭ ‬1846‭?
Classification: Chordata,‭ ‬Osteostraci,‭ ‬Cephalaspidiformes,‭ ‬Cephalaspidae.
Species: C.‭ ‬lyelli.
Diet: Carnivore/bottom feeder.‭
Size: Approximately‭ ‬20‭ ‬to‭ ‬30‭ ‬centimetres long.‭
Known locations: Western Europe.‭ ‬North America.
Time period: Early Devonian.
Fossil representation: Many specimens are known.

       Cephalaspis is a good example of the jawless fish that swam through the waters of the Devonian.‭ ‬Although jawless,‭ ‬it still had a mouth that was situated to the underside of the head,‭ ‬suggesting that it was a bottom feeder.‭ ‬Also there seems to be sensory organs on the underside of the head suggesting that it searched for buried prey items such as worms and microorganisms.‭ ‬It‭’‬s also likely that it would have sifted for organic matter that had sunk to the bottom.
       The armoured head of Cephalaspis is its most distinguishing feature taking up about a third of the body length and being almost as wide as it is long.‭ ‬With the mouth on the bottom of the head,‭ ‬the eyes are situated close together at the top of the skull.‭ ‬Since Cephalaspis probably did not rely on them for feeding,‭ ‬this was probably a defensive adaptation suggesting that Cephalaspis itself was prey for the predators of the time.
       There have been a large number of remains attributed to the genus Cephalaspis,‭ ‬ranging from Europe to North America and further beyond.‭ ‬However there are many people who remain unconvinced as to the validity of all the specimens,‭ ‬hence the changing lists of species depending upon source.‭ ‬Here in an attempt to avoid potential confusion,‭ ‬only the type species C.‭ ‬lyelli described by Agassiz is noted.

Further reading
- Recherches Sur Les Poissons Fossiles. Tome I (livr. 18). - Imprimerie de Petitpierre, Neuchatel xxxii-188. - Louis Agassiz - 1843.
- Concerning the Mouth Opening and certain features of the Visceral Endoskeleton of Cephalaspis. - Journal of Anatomy vol65. - Edward Phelps Allis Jr - 1931.
- On Cephalaspis magnifica Traquair, 1893, from the Middle Devonian of Scotland, and the relationships of the last osteostracans. - Transactions of the Royal Society of Edinburgh: Earth Sciences 9. - Philippe Janvier & Michael J. Newman - 2004.


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