Editing Placoderm (section)

====Arthrodira====
[[File:Dunkleosteus terrelli 2024 reconstruction.jpg|left|thumb|''[[Dunkleosteus]]'']]
[[Arthrodira]] ("jointed neck") were the most diverse and numerically successful of the placoderm orders, occupying roles from giant [[apex predator]]s to [[detritus]]-nibbling [[Benthic zone|bottom dweller]]s. They had a movable joint between armour surrounding the head and body. As the lower jaw moved down, the head shield moved, allowing for a larger opening. All arthrodires, save for ''Compagopiscis'', lacked teeth, and used instead the sharpened edges of a bony plate, termed a "tooth plate", as a biting surface (''Compagopiscis'' had true teeth in addition to tooth plates). The eye sockets are protected by a bony ring, a feature shared by birds and some [[ichthyosaurs]]. Early arthrodires, such as the genus ''[[Arctolepis]]'', were well-armoured fishes with flattened bodies. The largest member of this group, ''[[Dunkleosteus]]'', was a true "superpredator" of the latest Devonian period, reaching 3 to as much as 8 metres in length. In contrast, the long-nosed ''[[Rolfosteus]]'' measured just 15&nbsp;cm. Fossils of ''[[Incisoscutum]]'' have been found containing unborn fetuses, indicating that arthrodires gave birth to live young.<ref>{{cite news |url=https://www.sciencedaily.com/releases/2008/06/080606104814.htm |publisher=[[Science Daily]] |title=Fish 380 Million Years Old Found With Unborn Embryo |date=June 6, 2008}}</ref>