Heterosteus
Heterosteus is an extinct genus of heterosteid placoderm known from remains discovered in Europe and Greenland.Description
This genus includes the largest species in the family, and are among the largest arthrodires, as well, with the type species, H. asmussi, having an estimated body length of up to. The genus differs from Herasmius by having the orbits on slightly longer eyestalk-like projections. The various species are found in Givetian-aged deposits in Europe and Greenland. With the except of the German H. rhenanus, all species are known from freshwater deposits: H. rhenanus is based on fragments found in a marine deposit.
