Response to comment on "Exceptional preservation of organs in Devonian placoderms from the Gogo largerstätte".

Jensen et al . ( 1 ) question evidence presented of a chambered heart within placoderms, citing its small size and apparently ventral atrium. However, they fail to note the belly-up orientation of the placoderm within one nodule, and the variability of heart morphology within extant taxa. Thus, we remain confident in our interpretation of the mineralized organ as the heart.