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Ungulata

In traditional classification, "Ungulata" is a general term used to refer to mammals with hooves, including Perissodactyla and Artiodactyla. However, with the progress of molecular phylogenetic research, the traditional "ungulates" or "Ungulata" is not a strict monophyletic concept. In modern classification, whales (Cetacea) are included in even-toed ungulates and merged with even-toed ungulates (Artiodactyla) into "Cetartiodactyla". Therefore, when discussing ungulates today, they are usually broken down into two independent major living groups:

  1. Perissodactyla: including horses, rhinos, tapirs, etc., with an odd number of toes (the middle toe bears weight).

  2. Cetartiodactyla: integrates traditional even-toed ungulates (such as pigs, cattle, deer, camels) and cetaceans (whales, dolphins, porpoises) into a natural monophyletic group. Even-toed ungulates are characterized by an even number of toes on each foot (usually 2 or 4), while the evolution of whales shows that they are closely related to hippos.

Historically, "Ungulates" also included some extinct primitive groups (such as Callostomidae and "Obtsodontia" in a broad sense), but here we mainly focus on the two major living groups: Perissodactyla and Cetiformes.

I. Introduction to Hoofed Mammals

1. Traditional vs. Modern Classification:
Traditionally, “Ungulata” was used as a broad term to include all hoofed mammals. This encompassed horses, rhinos, tapirs (odd-toed) as well as pigs, camels, deer, cattle, and others (even-toed). However, with advances in molecular phylogenetics, it became clear that whales (Cetacea) share a close evolutionary relationship with hippopotamuses (Hippopotamidae), which are even-toed ungulates. As a result, whales have been placed within the same clade as even-toed ungulates, creating the order Cetartiodactyla. This modern grouping better reflects their evolutionary origins.

2. The Two Main Orders of “Ungulates”:

  • Perissodactyla (Odd-toed Ungulates): Horses, rhinos, and tapirs—characterized by having an odd number of toes (usually one or three) and bearing weight mainly on the middle toe.

  • Cetartiodactyla (Even-toed Ungulates + Whales): This group combines traditional Artiodactyla (even-toed ungulates like pigs, camels, deer, bovids) with Cetacea (whales, dolphins, porpoises). Even-toed ungulates typically have two or four toes, and whales are highly specialized aquatic descendants of ancient terrestrial ungulate ancestors.


II. Evolutionary History

  • In the Paleogene and Neogene periods (roughly 20–50 million years ago), hoofed mammals underwent extensive adaptive radiations, spreading across the globe.

  • Perissodactyls once included a much greater diversity, but only three families survive today. They dominated certain habitats in the past but declined due to changing climates and the rise of grasslands.

  • Artiodactyls diversified more extensively, giving rise to a broad range of large herbivores on land. Within the even-toed lineage, one group returned to the water, evolving into modern whales and dolphins. Molecular data confirm that whales are nested within the even-toed ungulates, closely related to hippos, leading to the modern concept of Cetartiodactyla.


III. Classification Tables

A. Perissodactyla (Odd-Toed Ungulates)

FamilyExample Genera/SpeciesNotes
Equidae (Horses, Zebras, Donkeys)Equus (horses, zebras, donkeys)Weight-bearing on a single central toe; adapted for running in open habitats.
Rhinocerotidae (Rhinoceroses)Rhinoceros (Indian rhino), Ceratotherium (white rhino)Thick-skinned herbivores with one or two horns, found in Africa and Asia.
Tapiridae (Tapirs)Tapirus (tapirs of Central/South America, Southeast Asia)Short, flexible proboscis; forest dwellers that feed on leaves and fruits.

B. Cetartiodactyla (Even-Toed Ungulates + Whales)

Even-Toed Ungulates (Artiodactyla)

FamilyExample Genera/SpeciesNotes
Suidae (Pigs)Sus (wild boar, domestic pig), Phacochoerus (warthog)Omnivorous, often with prominent canines; Old World distribution.
Hippopotamidae (Hippos)Hippopotamus amphibiusSemi-aquatic, closely related to whales at the molecular level; African.
Camelidae (Camels, Llamas)Camelus (camels), Lama (llamas), Vicugna (vicuñas)Adapted to arid and high-altitude environments in Africa, Asia, and South America.
Cervidae (Deer)Cervus (red deer), Rangifer (reindeer), Muntiacus (muntjacs)Males typically bear antlers (bone structures shed annually); widespread across Eurasia and the Americas.
Giraffidae (Giraffe, Okapi)Giraffa (giraffe), Okapia (okapi)African endemics, the giraffe is adapted to browsing high foliage.
Bovidae (Cattle, Sheep, Goats, Antelopes)Bos (cattle), Ovis (sheep), Capra (goats), various antelopesExtremely successful and diverse herbivores in Africa, Eurasia, and North America.

Whales (Cetacea, included in Cetartiodactyla)

FamilyExample Genera/SpeciesNotes
Balaenopteridae (Rorqual Whales)Balaenoptera (blue whale), Megaptera (humpback whale)Baleen whales filter-feeding on krill and small fish.
Balaenidae (Right Whales)Eubalaena (right whales)Slow-moving baleen whales that feed on zooplankton.
Physeteridae (Sperm Whales)Physeter (sperm whale)Deep-diving predators of squid; have a large, oil-filled head.
Delphinidae (Dolphins, Orcas)Tursiops (bottlenose dolphin), Orcinus (killer whale)Tooth-bearing whales, highly social and widespread.
Phocoenidae (Porpoises)Phocoena (harbor porpoise)Small toothed whales with shorter beaks, found in coastal waters.

(There are many other whale families; the above are representative examples.)


IV. Summary

The concept of “hoofed mammals” as a single order is outdated. Modern evolutionary and molecular studies have clarified their relationships, placing whales within the lineage of even-toed ungulates. Thus, today we speak of:

  • Perissodactyla (Odd-Toed Ungulates): Horses, rhinos, tapirs.

  • Cetartiodactyla (Even-Toed Ungulates + Cetaceans): Pigs, hippos, camels, deer, cattle, antelopes, and whales/dolphins.

This modern classification highlights the incredible evolutionary journey of some terrestrial herbivores that eventually took to the oceans and became fully aquatic cetaceans. By understanding these relationships, users can appreciate how modern taxonomy accurately reflects the deep evolutionary history and adaptation of hoofed mammals.

Carnivora Primates Rodents Chiroptera Eulipotyphla Ungulata Cetacea Lagoiformes Pholidota Proboscidea Monotremata
Tragelaphus derbianus

Tragelaphus derbianus

Tragelaphus derbianus

Features:Black marks on the ears and nose

Giant Eland (scientific name: Tragelaphus derbianus) has two subspecies.Giant Eland usually gathers in small groups of about 25, but large groups are not uncommon. The migration of the herd depends on the changing patterns of the seasons. Mature males are usually solitary, and male-female contact ca...

Tragelaphus buxtoni

Tragelaphus buxtoni

Tragelaphus buxtoni,mountain antelope, mountain antelope, alpine antelope, mountain antelope

Features:White patch between eyes, two white spots on cheeks, white spots on sides and rump

Mountain Nyala (scientific name: Tragelaphus buxtoni) is called Mountain Nyala in foreign language, and has no subspecies.Mountain Nyala is most active in the evening and early morning, collecting grass leaves, ferns, aquatic plants and lichens for food. In cold or hot weather, they often hide in de...

Tragelaphus angasii

Tragelaphus angasii

Tragelaphus angasii,White-striped antelope, white-spotted antelope, East African bushbuck, Anders's bushbuck, African bushbuck, Nyala bushbuck

Features:The fur is reddish brown with obvious stripes, very beautiful

Lowland Nyala (scientific name: Tragelaphus angasii) is called Lowland Nyala in foreign language, and has no subspecies.Lowland Nyala usually live alone or in small groups of 10. They have low territorial awareness, are shy, cautious, and highly vigilant. Males will stab their prey with their sharp...

Tetracerus quadricornis

Tetracerus quadricornis

Tetracerus quadricornis

Features:The male has two pairs of horns on his head, two between the ears and one on the forehead.

There are three subspecies of Tetracerus quadricornis.Tetracerus quadricornis do not live in groups, rarely more than two individuals are together. These animals are solitary, living in the same area for their entire lives. It is not known whether they are territorial animals. During the estrus peri...

Boselaphus tragocamelus

Boselaphus tragocamelus

Boselaphus tragocamelus,blue antelope, blue scimitar-horned antelope, Indian antelope, blue bull

Features:They have a white "beard" below their throats, their front legs are usually longer, and their legs are often marked with white "socks"

Bluebuck (scientific name: Boselaphus tragocamelus) is called Nilgai, Bluebuck in English, Nilgau in French, Nilgo in Spanish, Nilgau, Nilgauantilope in German, and has no subspecies.The blue antelope is a diurnal animal, more active in the early morning and evening. It lives in groups, with most se...

Pseudoryx nghetinhensis

Pseudoryx nghetinhensis

Pseudoryx nghetinhensis,Annamite antelope, Asian unicorn, Asian unicorn, Wuguang cattle, sword-horned cattle, Saura antelope

Features:It looks like an antelope, but when viewed from the side it appears to have only one horn, so it is also called the "Asian Unicorn".

The Saola (scientific name: Pseudoryx nghetinhensis), also known as Wu Guang Niu and Asian Qilin, is a monotypic species of the genus Saola in the family Bovidae of the order Artiodactylus. The Saola is a large mammal discovered in 1992. Its unique appearance caused a sensation in the scientific com...

Bubalus quarlesi

Bubalus quarlesi

Bubalus quarlesi,Mountain buffalo, Buffalo quagga

Features:It is the smallest species of buffalo.

Mountain buffalo (scientific name: Bubalus quarlesi) is called Mountain Anoa in English, Anoa de quarle, Anoa des montagnes in French, Anoa de Montaña in Spanish, Berg-Anoa, Berganoa in German, and has no subspecies. It is the smallest species in the genus Buffalo of the order Artiodactyla, family...

Bubalus mindorensis

Bubalus mindorensis

Bubalus mindorensis,Tamoro buffalo, Philippine buffalo, Mindanao buffalo, Mindoro buffalo

Features:The horns are short and black, and they are Y-shaped, not crescent-shaped like the buffalo.

Mindoro buffalo (scientific name: Bubalus mindorensis) is also known as Tamaraw in foreign languages. It has no subspecies. Mindoro buffalo only live in Mindoro. Together with the fossils of the genus Bubalus found on other islands, it shows that they were once widely distributed in the Philippines....

Bubalus depressicornis

Bubalus depressicornis

Bubalus depressicornis,Celebes buffalo, Lowland buffalo

Features:One of the smallest buffaloes in the world

Lowland buffalo (scientific name: Bubalus depressicornis) is called Lowland anoa in foreign language, and has no subspecies.Unlike other wild cattle, Lowland buffalo usually live alone. Mother-child pairs are common, and occasionally small herds of up to 5 are gathered. It is a terrestrial animal. M...

Bubalus arnee

Bubalus arnee

Bubalus arnee,Asian wild buffalo, Asian water buffalo, Indian wild buffalo

Features:Of all the bison species, the wild buffalo has the largest horns, which can reach up to 2 meters in size.

Wild buffalo (scientific name: Bubalus arnee) is called Wild Water Buffalo, Asian Buffalo, Asiatic Buffalo, Indian Buffalo, Indian Water Buffalo, Water Buffalo, Wild Asian Buffalo in English, Buffle d'Eau, Buffle de l'Inde in French, Búfalo arni in Spanish, Arni, Asiatischer Wasserbüffel i...

Bos grunniens

Bos grunniens

Bos grunniens

Features:It is the most famous livestock in the high altitude areas of central Asia.

Domestic Yak (scientific name: Bos grunniens) is an artificially cultivated animal of the order Artiodactyla, family Bovidae, and genus Bos. It is called "Zhong" in Tibetan and is the most typical animal on the Tibetan Plateau. It is large in size and has strong vitality.The length and fin...

Bos taurus

Bos taurus

Bos taurus,Cattle, European cattle

Features:Strong physique, mainly used for eating, labor, and some events

Domestic cattle (scientific name: Bos taurus) are also known as domesticated cattle or aurochs. They are a general term for many domesticated animals in the order Artiodactyla, family Bovidae, and genus Bos. There are 1.3 billion domestic cattle on Earth today, with a total of 897 breeds. They are g...

Bos sauveli

Bos sauveli

Bos sauveli,Kapolei cattle, gray cattle

Features:They are tall but narrow, and their hair is mostly brown, with older males having black hair.

Cambodian wild cattle (scientific name: Bos sauveli) English Kouprey, Grey Ox, French Boeuf gris Cambodgien, Spanish Toro Cuprey, German Kouprey, no subspecies. Cambodian wild cattle are a particularly rare wild cattle native to Southeast Asia. Scientists did not discover this wild cattle until 1937...

Bosprimigenius

Bosprimigenius

Bosprimigenius

Features:The ancestor of domestic cattle, now extinct

Bosprimigenius, scientific name, is a large cattle, now extinct. Its scientific name comes from the German word Auerochse, meaning primitive cattle. Extinct (1627).Aurochs is a legendary wild cattle. Although it is distributed in Europe, it is a completely different species from the European bison,...

Bison bonasus

Bison bonasus

Bison bonasus

Features:The largest native herbivore in Europe, with a very large body

European bison (scientific name: Bison bonasus) is called European Bison, European Bison, Wisent in English, Bison d'Europe, Bison d'Europe in French, Bisonte Europeo, Bisonte Europeo in Spanish, Europäischer Wisent, Wisent in German, and has two subspecies.The area of European bison habita...

Bison bison

Bison bison

Bison bison,bison, American buffalo, bison

Features:It is the national animal of the United States

American bison (scientific name: Bison bison) is called American Bison in English and Amerikanischer Bison in German. It has two subspecies.American bison live in large numbers on the Great Plains of the United States and Canada, from the Great Slave Lake in the far north of Canada to Mexico in the...

Raphicerus sharpei

Raphicerus sharpei

Raphicerus sharpei

Features:There is a white ring around the eyes and along the sides of the muzzle that extends into the nasal cavity

Sharpe's Grysbok (scientific name: Raphicerus sharpei) is called Sharpe's Grysbok in English, Grysbok de Sharpe in French, Sharpe se Grysbok in South Africa, and Sharpegreisbok in German. There is no subspecies.The Shamrock is easily distinguished from other members of the genus. The Shamroc...

Raphicerus melanotis

Raphicerus melanotis

Raphicerus melanotis

Features:Rather stocky, with large ears and white radial stripes on the inside

Black-eared antelope (scientific name: Raphicerus melanotis) is also known as Cape Grysbok, with no subspecies.Black-eared antelopes are territorial, and each animal has a clearly defined home. They mark nearby plants with scents from defecation, urination, and secretions from foot and preorbital gl...

Raphicerus campestris

Raphicerus campestris

Raphicerus campestris

Features:There is a circle of white hair around the big eyes, and a thin black triangle

Raphicerus campestris (Steenbok in English, Steenbok in French, Steenbok in South Africa, Steinbockchen in German) has 4 subspecies.The common duiker (Sylvicapra grimmia) is similar in size and color to the sylvicapra grimmia, but is usually more whitish (grey) in appearance. The common duiker usual...

Ourebia ourebia

Ourebia ourebia

Ourebia ourebia

Features:There is a line of white fur above the eyes and a bald black hairless patch under the ears

Orebia ourebia (scientific name: Ourebia ) is called Oribi in foreign language. It has 9 subspecies and is a medium-sized ungulate.Orebia usually live in pairs or small groups of up to 7. There is one adult male and up to three adult females in a group. These groups have their own territories,...

Oreotragus oreotragus

Oreotragus oreotragus

Features:The fur is thick and coarse, yellow and gray, with gray and white spots, and almost tailless.

Oreotragus oreotragus (English: Klipspringer, French: Oréotrague, South African: Klipspringer, German: Klippspringer, Dutch: "rock jumper"), with 11 subspecies.The average territory of the Oreotragus is about 0.081 square kilometers. The size of a male's territory will depend on the a...