Groenlandaspis is an extinct genus of arthrodire from the Late Devonian. Fossils of the different species are found in late Devonian strata in all continents except eastern Asia. The generic name commemorates the fact that the first specimens of the type species were found in Greenland. Description As with all other arthrodires, Groenlandaspis had a joint in the back of its head with its thoracic armor, allowing for its head to be thrown back, increasing its gape. However, as its head is somewhat compressed in comparison with many other arthrodires, and as the dorsal side came to a low, pyramid-like peak, it is believed that Groenlandaspis could not crane its head back very far. It was a relatively small fish, only in length on average, though one unusually large species, G. riniensis, reached almost a meter in length. It lived in coastal and fluvial waters, where it is thought to have fed on either very small prey, or detritus; the small dental plates in its mouth strongly suggest that it was incapable of tackling large prey. The possibility that the plates may have been used to, at times, feed on bivalves has also been muted. The body shape of the largest species G. riniensis suggests that it was most likely a benthic fish. The presence of crushing tooth plates in the form of flat, noded infragnathals and superagnathals suggest that the species' diet may have included prey with hard external shells such as molluscs, crustaceans or arthropods. The armor length of G. riniensis, according to the original description, was approximately , with the head shield having a very broad marginal plate and narrow pineal plate, with the nuchal relatively narrow, being approximately half as broad as it is long. The trunk shield of this species was characterized as having an anterior lateral plate which is almost as broad as long with a relatively straight anterior margin; the median dorsal plate is low with an apex that is posteriorly directed; its posterior dorsolateral plate is very narrow with inflexion of the main lateral line canal situated very close to posterior margin. This species has ornamentation of widely spaced, coarse tubercles. Groenlandaspis is unusual among placoderms in that it is known what color it was; preserved pigment cells in its fossils indicate that its posterior was red and its anterior was silvery-white in a countershaded pattern, camouflaging it in the murky, silty