Epigenetic modification can provide a mechanism for cells to ‘remember’ early developmental decisions in the absence of the signals which first initiated them. Methylation of CG dinucleotides is amongst the most iconic of all epigenetic systems because there is a well defined mechanism by which it transmits molecular memory following cell division. We have recently surveyed CG methylation in a wide range of vertebrates (>25 species) and characterised the methylome of a cartilagenous fish, the elephant shark (Callorhinchus milii). Despite last sharing a common ancestor with humans ~465 Mya, elephant shark shares many epigenetic characteristics with human, including an association between promoter methylation and gene silencing. These findings position the elephant shark as a valuable model to explore the evolutionary history and function of vertebrate methylation, and stimulate further questions surrounding what drives high levels of epigenetic memory and how it is reprogrammed between generations.