<p>This study presents a comprehensive characterization of a unique nonhuman primate mummy from the Americas, housed in the Museum of Archaeology at the Castle of Gottorf, Germany. In contrast to the previously reported primate mummies from archaeological sites in arid areas (northern Chile and Egypt), this specimen originates from a subtropical region, the Gran Chaco. Through molecular analysis, the mummy is identified as a black-and-gold howler monkey (<i>Alouatta caraya</i>), a primate species widely distributed in southern South America. The genetic assignment places the mummy in the northeastern region of Argentina. Externally, the mummy is well preserved. Dental morphometrics suggest that the primate is a young adult individual. An isotopic analysis indicates a non-anthropogenic folivorous diet and its geographic location in the biome of the Paraná River Basin. Thus, the monkey used to create this mummy was likely hunted or reared for a short period. Radiocarbon dating places the mummy between the late pre-Hispanic and early Colonial times. The mummy was created using a drying process and is accompanied by attire composed of Indigenous textiles, as well as feathers from American rhea and white herons. The mummy may have had a possible ceremonial purpose, as supported by ethnoprimatological evidence, such as the totemic qualities attributed to black-and-gold howler monkeys by current Indigenous societies of the Gran Chaco. The multidisciplinary approach employed in this study, which combines molecular, morphological, chronological, isotopic, historical/archival, and ethnoprimatological contextual data, provides novel insights into the treatment and significance of primate remains in the South American past.</p>