The musky rat-kangaroo (Hypsiprymnodon moschatus) is a small marsupial found only in the rainforests of northeastern Australia. First described in the later 19th century, the only other species are known from fossil specimens. They are similar in appearance to potoroos and bettongs, but are not as closely related. Their omnivorous diet is known to include materials such as fruit and fungi, as well as small animals such as insects and other invertebrates.

The description of this species, assigned to a new genus Hypsiprymnodon, was published in 1876 by Edward Pierson Ramsay, a curator at the Australian Museum. The syntypes are part of the museum's collection, mounted specimens of a male and female collected at Rockingham Bay, Queensland. Ramsay's specimens were obtained during European settlement of northeastern Australia on an expedition toward the Herbert River. A description of the species was provided by Richard Owen in the year after Ramsay's publication, the name Pleopus nudicaudatus, describing the five toes of the hind foot and its scaly, naked tail, is now regarded as a synonym. Ramsay had provisionally assigned the species to the genus Hypsiprymnus, but in his review of the dentition he proposed to separate them to a new genus. Hypsiprymnodon moschatus has been placed with the subfamily Hypsiprymnodontinae of the family Potoroidae, the most recent classification^[1] places it in the family Hypsiprymnodontidae with prehistoric taxa.

The specific epithet is derived from Latin term moschatus, meaning musky. The description as a new species of 'rat-kangaroo' was the last of the 19th century, bringing the total to nine species, and no other new species would be formally described for another 90 years.

Hypsiprymnodon moschatus is the smallest species of the macropod order, weighing around 500 grams (18 oz). The total length of the head and body is 155 to 270 millimetres (6.1 to 10.6 in), the weight range 360 to 680 grams (13 to 24 oz). Sexual dimorphism is not readily apparent in this species, although the females may be slightly larger. They have a long black tail, measuring from 125 to 160 mm (4.9 to 6.3 in). The appearance of the tail is scaly, rather than hairy, and proportionally shorter than the length of the head and body. Their ears are also nearly hairless and appear leathery. The pelage is a uniform, deep and rich brown colour with reddish highlights over most of the body, the head and lower parts are somewhat greyish. The dark and chocolatey colour of the fur distinguish them from the other living 'rat-kangaroos'. A steel grey colour at the head grades into the rich brown of the body. The feet of H. moschatus are blackish and, uniquely among the macropods, have five toes at the hind foot. A band of white, variously slight to distinct, appears from the belly toward the throat. The animal emits a noticeable musky odour.

Dentition of the species resembles that of the extant potoroids, but for that family's incisor formula of I3/1. The dental formula of H. moschatus is I3/2 C1/0 PM1/1 M4/4. Two premolars found in juveniles are replaced at maturity when a single sectorial premolar erupts. The sequence of emerging molars and premolars allows the age of the individual to be determined. Hypsiprymnodon moschatus have a fine and delicate skull structure with a rostrum that is narrow and elongate. A long nasal bone structure and distance between the canine and premolar teeth is large.

The species only occurs in the northeastern part of the continent. They may be locally common in remaining areas of extensive rainforest and can occur at high and low elevations. The distribution range extends from west of Ingham, Queensland at Mt. Lee to Mt. Amos south of Cooktown. They are found in low altitude rainforests, such as Cape Tribulation and Mission Beach, and within the montane habitat of the Carbine, Atherton and Windsor tableland regions. The population density of H. moschatus is from 1.40 to 4.50 animals per hectare.

A usually solitary animal that is only active during the day, distinguishing them from the nocturnal habits of the rat-kangaroos in the Potoroidae family. They are most active in the morning and afternoon, retiring to their shelter during the middle of the day. They are mostly terrestrial, foraging at the forest floor, although they are able to move through the branches of the lower vegetation.

A nest is roughly constructed at a site where the animal shelters while sleeping. Observations of the behaviour within its dense habitat presented difficulties to early field work, however, the use of a thread, lightly glued to the animal and fed from a spool, allowed the activity and range of males and females to be more accurately evaluated. The individual ranges overlap in both their foraging and nest site. Males may venture out in a range from 0.8 to 4.2 hectares, while females are recorded foraging over a smaller sized area of up to 2.2 ha. Although they are usually solitary in the activities, several may gather to feed at fallen fruit.