Exutaspis megista is an extinct, "giant" buchanosteidarthrodireplacoderm. Its fossils have been found in the Late Emsian-aged marine strata of the Jiucheng and Haikou Formations in Wuding, Yunnan.
It was originally described as a phlyctaeniid. Later, after comparison with the Chinese Buchanosteus guanxianesis, Exutaspis was reappraised as a buchanosteid. The holotype, a "head roof," is 21 cm (8.3 in) long.
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