Musky Rat-Kangaroo: Hypsiprymnodontidae

The musky rat-kangaroo is a small, four legged, marsupial mammal. It is different from most familiar mammals such as cats, dogs, and horses, which are known as placental or eutherian (yoo-THEER-ee-an) mammals. Eutherian mammals have a placenta, an organ that grows in the mother's uterus (womb) and lets the mother and developing offspring share food and oxygen. Marsupials do not have a well-developed placenta. Consequently, they give birth to young that are physically underdeveloped. These young are hairless, blind, and have immature organ systems. They are unable to survive on their own. Instead, after birth they are carried around for several months in their mother's pouch, where they are attached to the mothers teats, or nipples. They are carried and fed this way until they have grown and matured enough to fend for themselves.

Musky rat-kangaroos are fairly small. Their bodies are generally between 6 and 11 inches (15 to 30 centimeters), and they have a total length from nose to tip of the tail of about 11 to 17 inches (30 to 43 centimeters). Musky rat-kangaroos have short brown or reddish fur that is very soft on their backs, while fur on the underside of their belly is slightly paler. Some musky rat-kangaroos have distinctive white markings on their throats that continue in a white line down to their chest.

Musky rat-kangaroos have small heads that are narrow and taper into a pointed snout. Their ears are small and rounded, and their tails are long, thin, and hairless, except for the area where the tail joins the body. The musky rat-kangaroo has four paws with five toes on each of its back feet and four on its front feet. Like other kangaroos, the middle toes have a fused (grown together) bone but separate claws. However, all other living kangaroos have only four toes on their back feet. The fifth toe of the musky rat-kangaroo does not have a claw. It is thought that this extra toe is used to help it climb.

Female musky rat-kangaroos have four nipples inside a forward-opening pouch where the young are carried after birth. Female and male musky rat-kangaroos are about the same size, although females usually weigh a little less than males. The average weight of a musky rat-kangaroo is between 11 and 24 ounces (337 to 680 grams).