Xanthomyria is a genus of Cambrian arthropod from the Ust-Mayan Formation of Siberia.

However, various structures of the exoskeleton such as tuberculate and spinose tergites with a broad rachis and narrow pleurae rule out most Cambrian clades of arthropod, and unusually in this regard Xanthomyria is most similar to Carboniferous archipolypodans such as Euphoberia.

However, it is more likely that Xanthomyria instead belongs to a wholly extinct myriapod-like clade of arthropods along with forms like Pseudoiulia, due to true stem-group myriapods which appear very different having been found in the Cambrian, in the form of Euthycarcinoidea.

The trunk is roughly 5.2 cm long and had at least 34 segments (possibly over 60, if the smaller specimen is the tail end of a larger animal instead of being a juvenile), with a slight taper towards the back.

[1] Xanthomyria derives from the Greek words xanthos meaning "yellow", and myrios, meaning "countless" in reference to the yellowish colouration of the fossils alongside the inferred affinity with Myriapoda.