Overall, the evidence provided by the embryo suggests that "Dinocephalosaurus" was viviparous, making it the first viviparous archosauromorph asides from possibly metriorhynchids. This is consistent with the separation of its sacral ribs from its sacrum, which indicates a mobile pelvis that could have functioned in giving birth. While the otherwise absence of viviparous archosaurs has been historically attributed to common attributes inherited from the archosaurian stem-lineage, the discovery that "Dinocephalosaurus" was viviparous suggests that this phenomenon is due to lineage-specific lifestyle restrictions. Although the sex-determination systems among living archosauromorphs are diverse, with crocodilians and turtles using temperature-dependent sex determination, phylogenetic modelling suggests that "Dinocephalosaurus" retained the basal condition of genotypic sex determination from early diapsids, and that this system facilitated its transition to an obligately marine lifestyle alongside viviparity.