Aleosteus ("dice-shaped bone") is an extinct genus of arthrodire placoderm. Its fossils have been found in Sevy Dolomite Formation, in the Egan Range of east-central Nevada, USA. Almost complete fossils belong to juvenile and adult specimens and show a short and broad skull, posteriorly concave. Image:Acanthodii.jpg This prehistoric fish-related article is a stub. You can help Fossil Wiki by [ expanding it].