Guinea pig

There is sexual dimorphism in the domestic jackdaw.

An excerpt from the article 20 facts about guinea pig

Males are noticeably larger than females. Representatives of both sexes have one pair of nipples, each located in the axillary zone.

In both sexes, the appearance of external sexual characteristics is similar, the genitalia is located directly near the anus. Sex differentiation is possible mainly by examining the external genitalia.