The South-American stimpys are comparatively large for specworld mammals. These solitary folivorous marsupials may look somewhat similiar to koalas, but this has been proven to be mere convergence. Stimpys also resemble leaf-eating monkeys and sloths of Arel in some respects, and these animal are probably closer equivalents to these marsupials. Stimpys are not quite as harmless as they may look, but surprisingly their main defence against arboreal theropods seems to be size. A 15 kg spectacled stimpy is simply too much mammal for an average arbonychosaur to handle. Only when they have to climb down to the forest floor are they in danger to be snatched by a jagular.

    Stimpys are fairly silent creatures for most of their life, but during the mating they make an exception. The female in heat calls for males with a low howl: "Haah-peeh, haah-peeh, haah-peeh". Any nearby males answer to the female's call with a high-pitched "Djyo-ee, djyo-ee." According to the few that have had the opportunity to witness this have described the experience as "nothing short of surreal."