Hennig (1932, p. 135) proposed Sinanthropus (Pithecanthropus?) pekingensis based on material from Zhoukoutien. Campbell (1965) listed this name as a primary junior homonym of Sinanthropus pekinensis Black and Zdansky, 1927. Campbell (1965) remarks that the slight differences in spelling amount to an incorrect subsequent spelling (ISS) and the names 'pekinensis' and 'pekingensis' should be treated as homonyms (rather than synonyms) as directed under Article 33.3.
