What is Cephalaspis?
{{italictitle}} {{speciesbox | name = ''Cephalaspis'' | fossil_range = Early [[Devonian]] {{fossil range|415|398}} | image = Ostracoderm digital recreation..jpg | image_caption = Digital recreation of ''Cephalaspis'' | genus = Cephalaspis | parent_authority = Agassiz, 1835<ref>L. Agassiz. 1835. Recherches Sur Les Poissons Fossiles. Tome I (livr. 18).</ref> | species = lyelli | authority = Agassiz, 1835 }} [[File:Cephalaspis species.jpg|thumb|''Cephalaspis whitei, C. lyelli, C. poweri'' and ''C. magnificans'']] '''''Cephalaspis''''' (meaning 'head shield') is a [[Genus (biology)|genus]] of armoured fish in the early [[Devonian]] about 400 million years ago (mya). It was one of the [[jawless fish]]es, or [[ostracoderm]]s, which were common at the time. They were discovered in the first half of the 19th century in the [[Old Red Sandstone]] of [[Britain]]. [[Louis Agassiz]] named it in 1835.<ref>Agassiz L. 1835. ''Recherches sur les poissons fossiles''. Tome I (livr. 18).</ref> He had been to [[Scotland]], and seen [[Hugh Miller]]'s collection. Miller described his collecting later, in a popular work on the rocks and fossils of the [[Old Red Sandstone]] in [[Scotland]].<ref name=Miller>Miller, Hugh 1841. ''The Old Red Sandstone, or new walks in an old field''. Edinburgh: Johnstone.</ref> Agassoz' single species has now been split into more species, some of which have been moved into a different [[genus]].<ref>Janvier P. 1996. ''Early Vertebrates'' Oxford University Press.</ref> == Lifestyle == ''Cephalaspis'' was a medium-sized fish that lived in freshwater streams and estuaries of the early [[Devonian]]. Some of the fossils are well-preserved, and so we know quite a bit about its anatomy.<ref name=Benton>Benton, Michael. ''Vertebrate palaeontology''. London: Chapman & Hall, 2nd ed, p48/9.</ref> Its armour was on the [[dorsal]] side, and its mouth on the [[ventral]] side. Therefore, it is likely that it was a bottom-feeder, nosing about in the [[mud]] of a river. It had a typical vertebrate type of brain, with fr