Cephalaspis lyelli

Cephalaspis is a probably monotypic genus of extinct osteostracan agnathan vertebrate. It was a trout-sized detritivorous fish that lived in estuaries of the early Devonian.

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.