Originally classified by Yang in 1982 in Heterodontosauridae, Dianchungosaurus lufengensis affinities were doubted by some, who regarded it as a nomen dubium, but it was until recently usually considered a valid heterodontosaurid.
While birds are the best-known animals with this fused bone, they were not the only group and not even the first to have it: in a remarkable case of parallel evolution, a tarsometatarsus was also present in the Heterodontosauridae, a group of tiny ornithopod dinosaurs quite unrelated to birds.
It has sometimes been associated with heterodontosaurids, which appears to be due to the juxtaposition of a species of Dianchungosaurus (formerly thought to be a heterodontosaurid) in the text of Zhao (1985).