Calomys musculinus is a small rodent species belonging to the family Cricetidae. It is commonly found in the grasslands and scrublands of Argentina, Paraguay, and Uruguay. This species is characterized by its soft fur, long tail, and large ears, which help it adapt to its environment. These rodents primarily feed on seeds, fruits, and insects, playing a vital role in their ecosystem as seed dispersers. Calomys musculinus is also known for its reproductive adaptability, with females capable of producing multiple litters each year, contributing to its population stability in the wild.