This article addresses the assessment of anonymous artistry in rock art—something basically different from the attribution of later paintings, where extra-artistic information may help to attribute the work to a specific artist. No such information is normally available in the case of rock art. The most one can expect in that case is to reveal pictures by one and the same creator, or by his imitators. In this study, we used the method of Giovanni Morelli, who proposed to assess artistry on the basis of secondary details reproduced unconsciously. Two examples of such details are discussed in detail. One concerns structural elements such as fossa, fossula, foveola, insecta, and fissura, detected by traceological analysis of petroglyphs associated with the Tagar culture of Khakassia. Their occurrence and orientation provide clues as to individual motility and thereby to their creators, albeit anonymous. The second example concerns diagnostic features of the large marine mammals depicted in the petroglyphs of the Ulsan group, South Korea (Bangudae and Cheonjeon-ri). Animals represented in those petroglyphs can be diagnosed at the species level, and the way they are represented enables us to decide whether the artist himself observed them or whether he merely imitated someone else’s mannerisms.