Successor portraits, along with the introduction of dynastic phenotypes and their distribution across the empire, are among the most profound innovations of Roman portraiture practice under Julio-Claudian rule.
However, the portraits of these princes have resisted various attempts at explanation; the mechanics of this genre are still little understood.

This paper demonstrates what is gained, and what lost by approaching this material with specific sets of questions; it proposes a new framework of analysis and interpretation that zooms in on the way in which these portraits functioned in the public group portraits of the imperial family. 

Abstract