Frogs do not possess buttocks in the mammalian sense. Human buttocks consist primarily of the gluteus maximus, a muscle group adapted to stabilize an upright trunk while walking on two legs. Amphibian anatomy operates under an entirely different mechanical blueprint designed for explosive propulsion.
When anurans (frogs and toads) sit, their rear appearance is defined by their pelvic girdle and urostyle, an elongated fusion of caudal vertebrae. Flanking this central ridge are heavy leg flexors, including the semimembranosus and gracilis major muscles. These muscles generate massive kinetic output relative to body weight, allowing frogs to jump up to 20 times their own body length.
When a chubby species, such as the African bullfrog or the South American horned frog, rests in a relaxed crouch, those specialized jump muscles compress against their pelvic framework. Add a thick layer of hydration tissue and loose skin, and the silhouette mimics human curves. The internet's evolutionary tendency toward pareidolia does the rest. Viewers see an anthropomorphic rear end where biology has simply provided an efficient, spring-loaded chassis.
