Coprolites are a useful tool to obtain information related to the life history of the producer, trophic interactions, biodiversity, paleoenvironments, and paleoclimate, among other issues. We analyze here a sample of 111 coprolites recovered from levels of the Santa Cruz Formation (lower–middle Miocene, Burdigalian–early Langhian), outcropping in different localities of the Santa Cruz Province, Patagonian Argentina. Based on size and shape, two morphotypes were identified: coprolites assigned to morphotype I vary from ovoid to subspherical in shape, while coprolites assigned to morphotype II are cylindrical in shape. Several coprolites have bone and teeth inclusions belonging to small mammals (i.e., Octodontoidea and/or Chinchilloidea rodents). Morphometry, composition, and taphonomy of the bone remains suggest that the coprolites were produced by carnivorous mammals. According to the features of the guild of carnivorous mammals from the Santa Cruz Formation, we interpret that hathliacynids and/or small borhyaenoids (Sparassodonta) are the most probable producers. Different traces recorded in the coprolites, such as borings and putative eggs, suggest that the feces were exploited by coprophagous insects, probably dung beetles, for different purposes such as feeding and possible oviposition.