Evolution and systematics
Rat-kangaroos have been historically categorized as a subfamily of their nearest kinfolk, the kangaroo and wallaby household (Macropodidae). However, most taxonomists now settle for the separation of two teams into households with the Potoroidae being separated from the Macropodidae on the premise of their urogenital anatomy. The two teams are sometimes related right into a single superfamily, the Macropodoidea. These households have been separate for at the least 50 million years. Within the Potoroidae there may be one group: the Potoroinae, which accommodates the extant genera of Potorous, Bettongia, and Aepyprymnus. Within the Potoroinae, Bettongia and Aepyprymnus are extra intently associated to one another than to Potorous.
These animals are all smaller than a medium-sized cat. The higher fur is variously gray-brown with the stomach normally a lot lighter. The ears are quick and rounded. The face is brief although the nasal area is considerably elongated. The forelimbs are significantly shorter than the hind limbs, that are elongated in an identical method to that of the bigger kangaroos. The tail is normally furred, and within the brush-tailed bettong ( B. penicillata), there's a crest on the distal dorsal floor. In P. tridactlus and B. gaimardi, the tail tip is white; the importance of this isn't identified. Some bettongs have a prehensile tail that's used to transport nest materials (leaves and grass) for nest constructing. There are three pairs of higher incisors however just one pair of decrease, and younger potoroids have two premolars, although close to maturity these are changed by a single sectorial molar. The molar tooth erupt steadily and the fourth molar could not erupt for 3 to 4 years. There is a scarcity of ####ual dimorphism within the bettongs.
The household is confined to coastal Australia in primarily the southern half, although B. tropica is present in northeastern Queensland. Bettongia gaimardi is discovered solely on the island of Tasmania the place it's nonetheless regionally frequent. Potorous tridactlus is distributed from southern Queensland by way of New South Wales into most of Victoria in addition to Tasmania. Potorous longipes is just present in a really restricted space of Victoria whereas P. gilberti happens solely in Two People’s Bay Nature Reserve, Western Australia. Bettongia lesueur is discovered on just a few islands off the west coast of Western Australia and B. penicillata is present in pockets in southwest Western Australia and has been translocated to various islands off South Australia. Bettongia lesueur is restricted to solely three islands of the west coast of Western Australia. Aepyprymnus is discovered solely in New South Wales and Queensland.
Most potoroids stay in forest or woodland areas dominated by eucalyptus species. However, within the latest previous, B. lesueur and B. pencillata lived over a lot of arid Australia. Bettongia lesueur, the burrowing bettong, lives in warrens that may be in sandy dunes. Potoroos have a tendency to stay in wetter forest areas than the bettongs, which choose the extra open forest that's higher suited to their excessive hopping gait.
Not an excessive amount of behavioral research have been carried out on this nocturnal group. They are usually solitary, although some bettong men and women could cohabitate for brief intervals after mating. Males frequently inspect females dwelling of their residence vary by inspecting their pouch and/or urogenital areas. This permits males to concentrate on the reproductive standing of the feminine and the imminence of estrus. Males might be aggressive in the direction of different males, which usually takes the type of lashing out with their hind ft. Animals which are anxious typically show a sinuous motion of the tail. Female bettongs not in estrous may also be aggressive in the direction of unwelcome males, lashing out with their hind ft whereas mendacity on their facet. Mating takes place normally solely on the night time of estrus and includes rear-entry whereas the male holds the feminine together with his forelimbs round her flank. He may additionally maintain on to her neck together with his tooth. Intromission is normally of some seconds length however could happen a number of occasions in an evening. This group makes few vocalizations, although females make a clucking-like sound to appeal to their younger to the pouch. Anxious animals make a vocalization with an explosive expelling of air.
Feeding ecology and weight loss plan
The bettongs and potoroos are primarily fungivores, consuming a big proportion of the fruiting our bodies of underground (hypogeous) fungi. In order to accomplish this, it's needed that they've a well-developed sense of olfaction; a big proportion of their cortex is devoted to this. Animals dig with their forefeet to entry their weight loss plan. The well-developed forestomach of potoroids permits them to have adequate time to digest the fungi and the intestine flora/fauna help in offering important amino acids that could be absent from the weight loss plan. Animals can exist nearly solely on fungi, which give a nourishing weight loss plan excessive in each protein and lipid. The fungi develop on the roots of eucalyptus and different native bushes and their spores are activated throughout passage by way of the bettong’s intestine, thereby permitting germination on the website of defecation.
Rat-kangaroos are in all probability polygynous and have a reproductive biology fairly related to that of their bigger kinfolk, the kangaroos and wallabies. After a brief gestation, normally about three weeks, the neonate crawls unaided to the pouch the place it attaches to one of many 4 teats. On that night time the mom comes into estrous, termed a postpartum estrus, and mates once more. The resultant fertilized egg develops solely to the blastocyst stage of about 100 cells earlier than turning into dormant, termed embryonic diapause. It stays within the uterus till it's reactivated close to the top of pouch growth of the earlier younger. Then, normally on the identical night time that the big offspring lastly vacates the pouch, the brand new offspring is born. Again, the mom will come into postpartum estrus and mate once more. Thus, the rat-kangaroo can have three completely different generations on the similar time: one younger out of the pouch nonetheless suckling from her teat, one new child younger within the pouch, and one dormant embryonic stage in her uterus. All species give beginning to one younger at a time. The pouch contracts after the big offspring leaves the pouch, stopping its return and thereby defending the new child smaller younger. The milk suckled by the younger within the pouch is continually altering its composition from a dilute milk low in protein and lipid however excessive in carbohydrate to one which turns into extra concentrated and excessive in lipid and low in carbohydrate.
Bettongia tropica, Gilbert’s potoroo, and the long-footed potoroo are listed as Endangered within the Environment Protection and Biodiversity Conservation Act 1999 of the Commonwealth of Australia. Bettongia lesueur and the long-nosed potoroo in southeast Australia are listed as Vulnerable. The IUCN lists Gilbert’s potoroo as Critically Endangered, the long-footed potoroo and northern bettong as Endangered, boodie as Vulnerable, brush-tailed bettong as Lower Risk/ Conservation Dependent, and the Tasmanian bettong as Lower Risk/Near Threatened.