Chaeropus

Pig-footed bandicoot[1] Temporal range: Late Pliocene or Early Pleistocene–recent PreꞒ Ꞓ O S D C P T J K Pg N ↓
C. yirratji specimen, Grande galerie de l'évolution
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Infraclass:	Marsupialia
Order:	Peramelemorphia
Family:	†Chaeropodidae Gill, 1872
Genus:	†Chaeropus Ogilby, 1838[2]
Type species
Perameles ecaudatus Ogilby, 1838[2]
Species
Chaeropus ecaudatus Chaeropus yirratji Chaeropus baynesi (fossil)
Historic pig-footed bandicoot range in orange

Chaeropus, called pig-footed bandicoots, was a group of small marsupials that became extinct in the 20th century. They were the only animals in their family, Chaeropodidae, which is part of the bandicoot and bilby group (Peramelemorphia). They had very thin legs but could move quickly. Two known species^[3] lived in thick plants on dry and semi-dry plains in Australia. Later, they lived only in a desert area inland. The last time they were seen was in the 1950s, and now they are believed to be extinct.

The genus Chaeropus was suggested by William Ogilby during a talk at the Linnean Society of London. He thought it was a new type of bandicoot, similar to the long-nosed Perameles. He sent the information to John Gould in Sydney for a closer look. Ogilby used a drawing made by Major Mitchell, who also gave many details about the animal's shape and habits. Mitchell noticed the animal's unusual pig-like toes on its front legs and said this was why it should have its own genus. Mitchell found the animal in the interior of New South Wales, near the Murray River.^[2]

The name Chaeropus comes from Ancient Greek words meaning "pig" and "foot," because of the animal’s unique front feet. The species name ecaudatus means "without a tail," because the one specimen they had did not have a tail. This made people wrongly think the animal had no tail at all.^[4]

In 1904, Theodore S. Palmer published a list of names that are the same as this genus.^[4] Another name, Chœropus (or Choeropus), was made by Waterhouse in 1841, a few years after Ogilby, but it was not a correct change.^[5][6] Waterhouse also used Ogilby’s original spelling in the same work.^[7] Oldfield Thomas thought the name ecaudatus was wrong in 1888 and suggested a new name, Chœropus castanotis, given by John Edward Gray,^[8] but Palmer later said this new name was just another synonym and kept Ogilby’s name.

The common name, pig-footed bandicoot, was given by Ogilby in his first description. This name came from Mitchell's group.^[2] European settlers said the animal looked like "small antelopes,"^[9] a comparison that Bernard Woodward said was still used until the animals disappeared around 1900. The Noongar people called the animal boda, woda, or boodal. Indigenous Australian trackers knew it as landwang and tubaija in their culture.^[10][11]

This group, called a genus, used to be part of the family Peramelidae, which also includes bilbies. It was considered a subfamily called Chaeropodinae by McKenna and Bell in 1997. But the shape and features of this genus are quite different from others. Recent DNA studies support this difference. Scientists think it is closely related to, but separate from, the rest of the Peramelemorphia group. Because of this, it has its own family called Chaeropodidae.^[1] It is believed that Chaeropus split from other Peramelemorphia animals about 26.7 million years ago, during the Mid-Late Oligocene period.^[12]

Until 2019, both species in this genus were grouped together as one species called the pig-footed bandicoot (Chaeropus ecaudatus). But a study in 2019 split them into two species: the northern pig-footed bandicoot (Chaeropus yirratji) and the southern pig-footed bandicoot (Chaeropus ecaudatus).^[13] In 2016, scientists described a fossil species called Chaeropus baynesi from about 2.47 to 2.92 million years ago, found in southwest New South Wales.^[14]

The classification of these animals within the marsupials, based on the 2019 update, looks like this:

• Peramelemorphia

• Thylacomyidae (Macrotis, the bilbies)
• Chaeropodidae

• Chaeropus

• Chaeropus ecaudatus

• Chaeropus ecaudatus ecaudatus
• Chaeropus ecaudatus occidentalis

• Chaeropus yirratji

• Peramelidae (the living bandicoots)

A genus of marsupials in the Peramelemorphia group, this family is unique because of their special body shape.^[6] There are only 29 known specimens of the two species left in museums in Australia and other countries.^[15]

They looked a bit like native bandicoots or rat kangaroos but were very small and delicate, about the size of a young rabbit or kitten.^[16]

Their front feet looked like pig feet, and their back legs were like a horse's.^[16] The animals were about 23–26 cm (9.1–10.2 in) long, with tails 10–15 cm (3.9–5.9 in) long.^[17] At first, they looked like bilbies, with long, thin legs, big pointed ears, and long tails. But on closer look, they were very different from other marsupials. Their front feet had two toes with hooves, like pigs or deer.^[18] This might be because baby animals were placed in the pouch using outside stalks, so they didn’t need to use their front legs as babies.^[19] Their back feet had a big fourth toe with a strong claw like a small horse's hoof. The other toes were very small and not used for walking. Only the joined second and third toes were useful, but only for cleaning themselves.

They had wide heads and long, thin noses. Their fur was rough and straight, not spiky. Their color ranged from grey mixed with brown, to light brown or orange-brown. Their bellies and undersides were white, and their ears had chestnut-colored fur.

They had five pairs of upper front teeth and three pairs of lower front teeth. The shape of their teeth was different between the two species. Female animals had eight nipples, and their pouch opened backward, unlike kangaroos whose pouches open forward.^[20][21]

Pictures of these animals include a lithograph by Henry C. Richter in John Gould’s book The Mammals of Australia from the mid-1800s. Another drawing by Richter was found in the archives of Knowsley Hall, once home to a famous natural history supporter, the Earl of Derby.^[22] The species Chaeropus ecaudatus was painted by Peter Schouten and Tim Flannery in a book about animals that have gone extinct recently.^[16] Schouten also made another picture of the genus to show the species Chaeropus yirratji.^[15]

The two species lived in western New South Wales and Victoria, the southern parts of the Northern Territory, South Australia, and Western Australia.^[20] Chaeropus ecaudatus lived in the semi-dry southern parts of Australia, reaching as far as southwest Australia. Chaeropus yirratji lived in sandy areas from Western Australia to the deserts in central Australia.^[23] They lived in many types of places, such as grassy woodlands, grass plains, spinifex areas, and dry flat lands in central Australia. Even though they lived in a large area, they were never common and were spread out thinly.^[16]

There are only 29 complete specimens of these animals in museums.^[15] The first known specimen was found at Peron Peninsula during an 1818 expedition led by Louis de Freycinet. John Gilbert saw them in thick Casuarina seedling areas in southwest Australia but not near new settlements inland from Perth. On another trip, he found them at King George Sound on the southern coast of Western Australia.^[24] The species was not listed in the 1854 Austin Expedition, but a man named W. A. Sanford heard about an animal called the "chestnut-eared hog's-foot," which was probably this bandicoot and was common enough not to be mentioned. Later, other scientists like John Tunney, George Masters, and Guy Shortridge did not find the species in their surveys of western Australia.^[25] The last time the animal was seen in southwest Australia was in 1898 at Youndegin. This fits with a time when many medium-sized Australian mammals disappeared between 1875 and 1925.^[26][24]

Fossil evidence shows that this genus had a bigger range during the Holocene and earlier Pleistocene times. Fossils were found in Mammoth Cave (Western Australia) in Western Australia in the early 1900s, and later fossils were found in eastern Queensland,^[27] showing that the animal lived there when open grassy lands replaced rainforests.^[28] In northeast South Australia, a small bone was found in an owl pellet buried in the ground.^[29]

In 1921, explorer Samuel Albert White saw the animal’s tracks and learned it lived on rocky tablelands and sand dunes in central Australia. With help from a local Aboriginal woman and her dogs, he caught one.^[30] Because the animal was becoming rare, the Australian government banned exporting it, either alive or as skin, in 1921.^[31]

According to stories from Indigenous Australians, pig-footed bandicoots were already rare before Europeans came to Australia.^[21] Their numbers were going down even when scientists first learned about them in the mid-1800s. In 1857, local people gave two pig-footed bandicoots to Gerard Krefft, who was part of the Blandowski Expedition. Krefft showed a drawing to his collectors that showed the animal without a tail, but the first animals they gave him were bandicoots with their tails cut off. Krefft worked hard to get live animals and even said sorry for eating one of them.^[32][33] Only a few specimens were collected in the late 1800s, mostly from northwestern Victoria and also from dry areas in South Australia, Western Australia, and the Northern Territory. By the early 1900s, they were extinct in Victoria and southwest Western Australia. The last sure specimen was collected in 1901. By 1945, Chaeropus ecaudatus was extinct, gone from South Australia, and Chaeropus yirratji was only found in a small area in central Australia.^[21] However, Aboriginal people said that Chaeropus yirratji lived as late as the 1950s in the Gibson Desert and Great Sandy Desert in Western Australia.^[34]

The reason for their extinction is not clear. The red fox and European rabbit, which caused harm to many animals, had not yet reached southwest Western Australia when the pig-footed bandicoots disappeared there. Feral cats were common and might have caused some harm. Another possible reason is a change in their habitat. For thousands of years, Aboriginal people used controlled burning, which kept the land healthy by creating a mix of new and old plants for food and shelter. But during the 1800s, the Aboriginal population dropped by about 90% because of diseases brought by Europeans. The remaining Aboriginal people were often not allowed to continue their traditional land care and hunting. After this, many sheep and cattle were brought in, which changed the soil, plants, and food available for animals.

Scientists also think a disease outbreak might have caused many mammals, including pig-footed bandicoots, to die out. Hal Colebatch wrote in 1929 that their disappearance was not caused directly by settlers but by a natural event we do not understand. Some mammals returned to areas after local die-offs, but pig-footed bandicoots did not. Models show that these animals had no protection against this possible disease.^[35]

A study in 1988 asked Aboriginal people in central Australia about the animal. They said it had not been seen in southern areas for about 70 years but lived in central desert areas until 30 to 50 years before that.^[36]

Few naturalists saw and wrote about how the two species behaved. One report said it moved "like a tired horse running slowly, dragging its back legs."^[37] But Aboriginal people in central Australia, who knew the animal well, said that if scared, it could run very fast in a smooth galloping run.

Chaeropus species walked in a special way, with long, thin legs that looked like those of a big grazing animal, like an African antelope.^[24] Their front legs had two working toes, and their back legs had a hoof-like toe. This helped them run quickly to escape danger.^[16] They lived alone and were active at night. During the day, they slept in shelters and came out in the evening to find food using their strong sense of smell.^[17]

Depending on where they lived, pig-footed bandicoots used different kinds of shelters to hide from predators and sleep. John Gilbert found a nest near Northam, Western Australia, that looked like nests made by quenda and marl but had more leaves.^[24] In forests and grasslands, they used hollow logs or nests made of grass. In dry, treeless areas, they dug short, straight burrows with a nest at the end.

From old reports and studies of their teeth and stomachs, pig-footed bandicoots ate mostly plants. Their teeth showed they ate mostly leaves, roots, and grasses.^[38] In captivity, they liked meat, and Aboriginal people said they also ate grasshoppers, ants, and termites. They drank a lot of water when kept in captivity.^[16]

Tim Flannery thinks they bred between May and June and usually had twins. Because of the size of their pouch and comparing them to similar marsupials, they probably had no more than four babies at a time.^[17] A letter from Ludwig Glauert, who reported the animal’s disappearance years earlier, said the animal was very delicate and would die if caught and handled roughly.^[26]

• Waterhouse, G.R. (1841). Jardine, William (ed.). "Marsupialia, or pouched animals /". The Naturalist's Library. Conducted by Sir William Jardine, Bart. F.R.S.E., F.L.S., &c. &c. 11. Edinburgh: W.H. Lizars: 163.