Mammalian Mammary Mystery: Nipples, nipples, nipples...

[levdrakon]

Even male dolphins may have retained some evidence of nipples, according to this.

Males have two slits that look similar to an exclamation point. The long anterior slit houses the genital region, while the smaller posterior slit houses the anal region. Two small pores are present on either side of the genital-anal slit, which have been considered possible vestigial nipples.