Marmosets are small, arboreal primates that live in diverse ecosystems. 1,2 They have an extensive geographic distribution, being found in Central and South American countries, from Panama to southern Brazil. 3 In Brazilian biomes, they adapt to different environmental conditions, with the white-tufted marmoset (Callithrix jacchus, Linnaeus, 1758) inhabiting the Caatinga and Atlantic Forest, whereas the black-tufted marmoset (Callithrix penicillata, É. Geoffroy, 1812), while also found in these regions, mainly occupies the Cerrado. 4,5,6 The main challenges faced by individual marmosets are the destruction or fragmentation of their habitat, food shortages, hybridization, and the illegal pet trade. 4,7,8 The species of the genus Callithrix, such as C. jacchus and C. penicillata, due to their phylogenetic proximity, have similar morphology and body weight. 1,7,8 For this reason, in research, often the species of the genus are grouped and evaluated together. In captive callitrichids, studies using limb measurement and pelvimetry in association with radiographic examination have provided important data that aid in the determination of anatomical characteristics and differences between individuals of the same sex and between healthy and sick animals. 9,10,11 However, information regarding the measurement