Wombat
Wombats are short-legged, muscular quadrupedal marsupials that are native to Australia. They are about 1 m (40 in) in length with small, stubby tails and weigh between 20 and 35 kg (44 and 77 lb). All three of the extant species are members of the family Vombatidae. They are adaptable and habitat tolerant, and are found in forested, mountainous, and heathland areas of southern and eastern Australia, including Tasmania, as well as an isolated patch of about 300 ha (740 acres) in Epping Forest National Park[2] in central Queensland.
Though genetic studies of the Vombatidae have been undertaken, evolution of the family is not well understood. Wombats are estimated to have diverged from other Australian marsupials relatively early, as long as 40 million years ago, while some estimates place divergence at around 25 million years.[3]: 10– While some theories place wombats as miniaturised relatives of diprotodonts, such as the rhinoceros-sized Diprotodon, more recent studies place the Vombatiformes as having a distinct parallel evolution, hence their current classification as a separate family.[4]
Wombats dig extensive burrow systems with their rodent-like front teeth and powerful claws. One distinctive adaptation of wombats is their backward pouch. The advantage of a backward-facing pouch is that when digging, the wombat does not gather soil in its pouch over its young. Although mainly crepuscular and nocturnal, wombats may also venture out to feed on cool or overcast days. They are not commonly seen, but leave ample evidence of their passage, treating fences as minor inconveniences to be gone through or under.
Wombats leave distinctive cubic feces.[5] As wombats arrange these feces to mark territories and attract mates, it is believed that the cubic shape makes them more stackable and less likely to roll, which gives this shape a biological advantage. The method by which the wombat produces them is not well understood, but it is believed that the wombat intestine stretches preferentially at the walls, with two flexible and two stiff areas around its intestines.[6] The adult wombat produces between 80 and 100, 2 cm (0.8 in) pieces of feces in a single night, and four to eight pieces each bowel movement.[7][8] In 2019 the production of cube-shaped wombat feces was the subject of the Ig Nobel Prize for Physics, won by Patricia Yang and David Hu.[9]
Wombats are herbivores; their diets consist mostly of grasses, sedges, herbs, bark, and roots. Their incisor teeth somewhat resemble those of rodents (rats, mice, etc.), being adapted for gnawing tough vegetation. Like many other herbivorous mammals, they have a large diastema between their incisors and the cheek teeth, which are relatively simple. The dental formula of wombats is 1.0.1.41.0.1.4 × 2 = 24.
Wombats' fur can vary from a sandy colour to brown, or from grey to black. All three known extant species average around 1 metre (3 ft 3 in) in length and weigh between 20 and 35 kg (44 and 77 lb).
