Molecular clock
Phylogenetic analysis, based on mitochondrial DNA, has concluded that the sand devil and the Pacific angel shark ("S. californica") are sister species. The two of them in turn form a clade with other angel sharks found in the Americas. Molecular clock estimation has timed the divergence of "S. dumeril" and "S. californica" at "c." 6.1 Ma, around the time that the Isthmus of Panama formed. The rise of the Isthmus likely split the ancestral angel shark population, leading to their becoming separate species.