Abstract Placoderms, representing phylogenetically more inclusive jawed vertebrates and successive sister taxa to crown‐group gnathostomes, are critical to our understanding of character evolution within the crown‐group (chondrichthyans + osteichthyans), including developmental characters. Early ontogenetic stages of placoderms are generally poorly known, although some exceptional faunas preserve both embryonic (e.g. from the G ogo F ormation, W estern A ustralia) and post‐embryonic individuals (the M iguasha F ormation, C anada; L ode F ormation, L atvia; M erriganowry F ormation, G ogo F ormation, A ustralia). Information provided by these ontogenies is relevant to questions of placoderm taxonomy and phylogeny, but also to broader questions pertinent to vertebrate evolution as a whole, for example, evolution of bone development, evolution of the axial skeleton and evolution of reproduction.