Equidae is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. The family evolved around 50 million years ago from a small, multi-toed ungulate into larger, single-toed animals. All extant species are in the genus Equus, which originated in North America. Equidae belongs to the order Perissodactyla, which includes the extant tapirs and rhinoceros, and several extinct families.
Perissodactyla is an order of ungulates. The order includes about 17 living species divided into three families: Equidae, Rhinocerotidae (rhinoceroses), and Tapiridae (tapirs). They typically have reduced the weight-bearing toes to three or one of the five original toes, though tapirs retain four toes on their front feet. The nonweight-bearing toes are either present, absent, vestigial, or positioned posteriorly. By contrast, artiodactyls bear most of their weight equally on four or two of the five toes: their third and fourth toes. Another difference between the two is that perissodactyls digest plant cellulose in their intestines, rather than in one or more stomach chambers as artiodactyls, with the exception of Suina, do.
Tapirs are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a pig, with a short, prehensile nose trunk. Tapirs inhabit jungle and forest regions of South and Central America and Southeast Asia. They are one of three extant branches of Perissodactyla, alongside equines and rhinoceroses. Only a single genus, Tapirus, is currently extant. Tapirs migrated into South America during the Pleistocene epoch from North America after the formation of the Isthmus of Panama as part of the Great American Interchange. Tapirs were formerly present across North America, but became extinct in the region at the end of the Late Pleistocene, around 12,000 years ago.
The South American tapir, also commonly called the Brazilian tapir, the Amazonian tapir, the maned tapir, the lowland tapir, anta, and la sachavaca, is one of the four recognized species in the tapir family. It is the largest surviving native terrestrial mammal in the Amazon.
Tapirus is a genus of tapir which contains the living tapir species. The Malayan tapir is usually included in Tapirus as well, although some authorities have moved it into its own genus, Acrocodia.
Macrauchenia is an extinct genus of large ungulate native to South America from the late Pliocene to the end of the Pleistocene. It is a member of the extinct order Litopterna, a group of South American native ungulates distinct from the two orders which contain all living ungulates which had been present in South America since the early Cenozoic, over 60 million years ago, prior to the arrival of living ungulates in South America around 2.5 million years ago as part of the Great American Interchange. The bodyform of Macrauchenia has been described as similar to a camel, being one of the largest known litopterns, with an estimated body mass of around 1 tonne. The genus gives its name to its family, Macraucheniidae, which like Macrauchenia typically had long necks and three toed feet, as well a retracted nasal region, which in Macrauchenia manifests as the nasal opening being on the top of the skull behind the eye sockets. This has historically been argued to correspond to the presence of a tapir-like proboscis, but some recent authors suggest a moose-like prehensile lip or a saiga antelope-like nose to filter dust are more likely.
Nannippus is an extinct genus of three-toed horse endemic to North America during the Miocene through Pleistocene, about 13.3—1.8 million years ago (Mya), living around 11.5 million years. This ancient species of three-toed horse grew up to 3.5 feet and weighed between 165 pounds to 199 pounds, which was around the same size as a domestic sheep.
The giant tapir is an extinct species of tapir that lived in southern China, Vietnam and Laos, with reports suggesting it also lived in Taiwan, Java, and potentially Borneo. The species has been recorded from Middle and Late Pleistocene. There is only weak evidence for a Holocene survival. Tapirus augustus was larger than any living tapir, with an estimated weight of about 623 kilograms (1,373 lb). The species was also placed in its own genus of Megatapirus, however, it is now conventionally placed within Tapirus.
Protapirus is an extinct genus of tapir known from the Oligocene and Miocene of North America and Eurasia.
Tapirus californicus, the California tapir, is an extinct species of tapir that inhabited North America during the Pleistocene. It became extinct about 13,000 years ago.
Tapirus merriami, commonly called Merriam's tapir, is an extinct species of tapir which inhabited North America during the Pleistocene.
Tapirus haysii, commonly known as Cope's tapir, is an extinct species of tapir that inhabited North America during the early to middle Pleistocene Epoch (~2.5–1 Ma). The fossil remains of two juvenile T. haysii were collected in Hillsborough County, Florida on August 31, 1963. It was the second largest North American tapir; the first being T. merriami.
Tapirus cristatellus is an extinct species of tapir from the Pleistocene of South America. Remains are known from Brazil, specifically the states of Minas Gerais and Bahia.
Tapirus greslebini is an extinct species of tapir that lived in South America during the Pleistocene.
Tapirus lundeliusi is an extinct species of tapir that lived in Florida in the early Pleistocene. It was similar in size and shape to the still-living mountain tapir, with an estimated weight of 203 kg
Tapirus mesopotamicus is an extinct species of tapir that lived in South America during the Pleistocene. It is considered a possible ancestor of all extant South American tapirs.
Tapirus oliverasi is likely an invalid extinct species of tapir from South America.
Tapirus rondoniensis is an extinct species of large sized tapir that lived in northwestern parts of Brazil during the Pleistocene. Fossils of the species were found in the Río Madeira Formation of Rondônia, after which the species is named.
Trichechus hesperamazonicus, the western Amazonian manatee, is an extinct species of manatee that lived about 40 thousand years ago in the Madeira River, in the Brazilian state of Rondonia. It is known from this single locality, with possible occurrences in the Brazilian state of Acre.
