Red-legged short-tailed opossums have a body length of approximately 16 cm, a tail length of roughly 9 cm, and weigh between 67 and 95 g. Males are reported to be slightly larger than females.
One distinctive feature of M. brevicaudata is that members of the species usually have grey or black fur on their backs, reddish fur on their sides continuing onto the legs, and black feet and tail. Their tails are very short and furred. Their fur is usually short and dense.
The skull is characterized by the presence of the jugal and zygomatic arch. The dental formula of this opossum species is 5/4, 1/1, 3/3, 4/4= 50.
Range mass: 67 to 95 g.
Average length: 16 cm.
Sexual Dimorphism: male larger
Average basal metabolic rate: 0.366 W.