|Male at the Phoenix Zoo|
|Female at the San Diego Zoo|
Parachoerus wagneriRusconi, 1930
The Chacoan peccary or tagua (Catagonus wagneri or Parachoerus wagneri) is the last extant species of the genus Catagonus;  it is a peccary found in the Gran Chaco of Paraguay, Bolivia, and Argentina. Approximately 3,000 remain in the world.
The Chacoan peccary has the unusual distinction of having been first described in 1930 based on fossils and was originally thought to be an extinct species. In 1971, the animal was discovered to still be alive in the Chaco region, in the Argentine province of Salta. The species was well known to the native people, but it took a while for Western scientists to acknowledge its existence. It is known locally as the tagua.
The Chacoan peccary is notable in that it is not the type species of its genus, Catagonus, despite being the only living representative. Instead, the type is the extinct Catagonus metropolitanus . Such a case is an example of a Lazarus taxon, and shares this trait with another South American native, the bush dog. The Chacoan peccary was first described by scientists in 1972. 
A 2017 study on the phylogenetic systematics of Tayassuidae species suggests that Catagonus should only contain C. metropolitanus. The extinct narrow-headed peccary (C. stenocephalus) should be moved into Brasiliochoerus, while the Chacoan peccary, Catagonus bonaerensis and Catagonus carlesi should be placed in Parachoerus.  If this is accepted, then Catagonus becomes an extinct genus once more.
The Chacoan peccary is confined to hot, dry areas. Dominated by low-lying succulents and thorny bushes, the Gran Chaco is about 140,000 km2. A few scattered giant trees are found, but the majority of the vegetation is thorny scrub vegetation. The Chacoan peccary has developed adaptations such as well-developed sinuses to combat dry, dusty conditions. Their feet are also small, which allows maneuverability among spiny plants.
The largest of the three generally accepted species of peccaries, the Chacoan peccary has many pig-like features. It is an ungulate with a well-formed rostrum with a tough leathery snout. The bristle-like hair is generally brown to almost gray. A dark stripe runs across the back, and white fur is on the shoulders. Chacoan peccaries differ from other peccary species by having longer ears, snouts, and tails. It has white hairs around the mouth, unlike other peccaries. Catagonus wagneri also has a third hind toe, but other peccaries only have two. The hypsodont teeth follow this dental formula: 2/3, 1/1, 3/3, 3/3. The upper canines display the distinguishing trait of peccaries, pointing downwards instead of out and up like
glands, which may be a signal for other peccaries to keep the group together through the dense bush. 
Young are generally born between September and December, but litters have been found almost year-round. Births have been linked to periods of food abundance and rainfall. The average number of embryos has been recorded as approximately 2.72. Females may leave the herd to give birth and then return afterwards. Newborns are precocial, able to run a few hours after birth. The pelage of the young resembles that of the adults. There is no sexual dimorphism.
Chacoan peccaries often travel in herds of up to 20 individuals. They are active during the day, especially in the morning when they are most apt to travel. Herds display a general travel cycle within their home range of 42 days. This allows the individuals to monitor and show ownership over their areas.
These social mammals communicate by various sounds, ranging from grunts to chatters of the teeth. Though individuals may occasionally exhibit aggressive behavior such as charging and biting, this species is not as aggressive as others.
As a defensive strategy, members of a herd may line up in a defensive wall; this makes the herds harder targets for hunters. The Chacoan peccary produces a milky, odorous substance used for marking trees, shrubs, and similar. The substance is secreted from glands located on their backs, and is dispersed by rubbing. Frequently bathing in mud or dust, Chacoan peccaries also defecate at particular "stations".
The arid habitat of the Gran Chaco region provides very tough vegetation for the Chacoan peccary. These peccaries feed on various species of cacti, such as Cleistocactus baumannii and Opuntia discolor. It uses its tough snout to roll the cacti on the ground, rubbing the spines off. It may pull off the spines with its teeth and spit them out. The kidneys are specialized to break down acids from the cacti. The two-chambered stomachs are also well suited to digest tough foods. Occasionally grazing on bromeliad roots, it also eats acacia pods and fallen cactus flowers. This species of peccary seeks out salt licks formed from ant mounds and construction projects (road building and land clearings). The Chacoan peccary gains essential minerals like calcium, magnesium, and chlorine from the salt licks.
Because the Chacoan peccary is endemic to a formerly isolated region of South America, it is most vulnerable to human activity. Just as quickly as this species is discovered in an area, it disappears. Herd numbers are decreasing as a result of habitat loss and fragmentation. Their range is being quickly transformed into large Texas-style ranches. Hunting also continues, as well as an unidentified disease that has plagued the herds in recent years. A population has been established in North American and European zoos. Preserves have also been established in Paraguay, but are not highly enforced.
A peccary is a medium-sized, pig-like hoofed mammal of the family Tayassuidae. They are found throughout Central and South America, Trinidad in the Caribbean, and in the southwestern area of North America. They usually measure between 90 and 130 cm in length, and a full-grown adult usually weighs about 20 to 40 kg. They represent the closest relatives of the family Suidae, which contains pigs and relatives. Together Tayassuidae and Suidae are grouped in the Suina within the Artiodactyla.
The year 1975 in science and technology involved some significant events, listed below.
Suina is a suborder of omnivorous, non-ruminant artiodactyl mammals that includes the domestic pig and peccaries. A member of this clade is known as a suine. Suina includes the family Suidae, termed suids, known in English as pigs or swine, as well as the family Tayassuidae, termed tayassuids or peccaries. Suines are largely native to Africa, South America, and Southeast Asia, with the exception of the wild boar, which is additionally native to Europe and Asia and introduced to North America and Australasia, including widespread use in farming of the domestic pig subspecies. Suines range in size from the 55 cm (22 in) long pygmy hog to the 210 cm (83 in) long giant forest hog, and are primarily found in forest, shrubland, and grassland biomes, though some can be found in deserts, wetlands, or coastal regions. Most species do not have population estimates, though approximately two billion domestic pigs are used in farming, while several species are considered endangered or critically endangered with populations as low as 100. One species, Heude's pig, is considered by the International Union for Conservation of Nature to have gone extinct in the 20th century.
The Gran Chaco or Dry Chaco is a sparsely populated, hot and semiarid lowland natural region of the Río de la Plata basin, divided among eastern Bolivia, western Paraguay, northern Argentina, and a portion of the Brazilian states of Mato Grosso and Mato Grosso do Sul, where it is connected with the Pantanal region. This land is sometimes called the Chaco Plain.
The Paraguayan Chaco or Región Occidental is a semi-arid region in Paraguay, with a very low population density. The area is being rapidly deforested. Consisting of more than 60% of Paraguay's land area, but with less than 10% of the population, the Chaco is one of the most sparsely inhabited areas in South America.
The collared peccary is a species of artiodactyl (even-toed) mammal in the family Tayassuidae found in North, Central, and South America. It is the only member of the genus Dicotyles. They are commonly referred to as javelina, saíno, or báquiro, although these terms are also used to describe other species in the family. The species is also known as the musk hog. In Trinidad, it is colloquially known as quenk.
The white-lipped peccary is a species of peccary found in Central and South America and the only member of the genus Tayassu. Multiple subspecies have been identified. White-lipped peccaries are similar in appearance to pigs, but covered in dark hair. The range of T. pecari, which extends from Mexico to Argentina, has become fragmented, and the species's population is declining overall. They can be found in a variety of habitats. Social animals, white-lipped peccaries typically forage in large groups, which can have as many as 300 peccaries.
Catagonus is a genus of peccaries that contains the living Chacoan peccary and several extinct species. The genus has always been restricted to South America.
Archaeotherium is an extinct genus of entelodont artiodactyl endemic to North America during the Eocene and Oligocene epochs (35—28 mya), existing for approximately 9.1 million years. Archaeotherium fossils are most common in the White River Formation of the Great Plains, but it has also been found in the John Day Basin of Oregon and the Trans-Pecos area of Texas.
Platygonus is an extinct genus of herbivorous peccaries of the family Tayassuidae, endemic to North and South America from the Miocene through Pleistocene epochs, existing for about 10.289 million years. P. compressus stood 2.5 feet tall.
The Chacoan naked-tailed armadillo is a species of South American armadillo.
The Gran Chaco is a plain of about 1.000.000 km2. It covers parts of Bolivia, Paraguay, Brazil and Argentina.
Kaa-Iya del Gran Chaco National Park and Integrated Management Natural Area is the biggest national park in Bolivia and one of the largest in South America. It is a protected area in the region of the Gran Chaco and has a larger surface area than Belgium. It is situated in the south of Santa Cruz Department on the border with Paraguay in the Cordillera Province and Chiquitos Province.
The chacoan gracile opossum is a species of opossum in the family Didelphidae. It is native to Argentina, Brazil and Paraguay. Its habitat is seasonally flooded grasslands and forests in and near the Gran Chaco.
Platygonus compressus, the flat-headed peccary, is an extinct mammal species from the Tayassuidae-family, that lived in North-America during the Pleistocene. It was first described in 1848 by John L. Leconte.
Catagonus stenocephalus is an extinct species of peccary that lived in South America during the Late Pleistocene. Fossils have been found in Brazil, Argentina and Bolivia. It is commonly known as the narrow-headed peccary due to its long and markedly convex rostrum.
Catagonus metropolitanus is an extinct species of peccary known from the Pleistocene of Argentina.
Catagonus carlesi, or Parachoerus carlesi, is an extinct species of peccary that lived in Argentina during the Late Pleistocene.