Home>>All Animals>>Mammal>>Ungulata

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 Pangolins Proboscidea Monotremata
Pudu mephistophiles

Pudu mephistophiles

Pudu mephistophiles,De Winton

Features:Antlers are short and have only a simple trunk

Pudu mephistophiles (De Winton) is also known as the northern Pudu deer.Pudu mephistophiles mainly eat understory plants in moist forests, including ferns and leaves. Because their food is full of water, they rarely drink water. They defecate in the same place, forming a pile of dung, which may be u...

Ozotoceros bezoarticus

Ozotoceros bezoarticus

Ozotoceros bezoarticus

Features:Male savannah deer have well-developed scent gland sacs on their hind legs

The scientific name of the steppe deer is Ozotoceros bezoarticus, which is an endangered deer species unique to South America. In spring, they often gather in small groups of 3 to 5, and live alone or in pairs in winter. It is small and looks unremarkable. However, the male steppe deer has developed...

Blastocerus dichotomus

Blastocerus dichotomus

Blastocerus dichotomus,Swamp Deer

Features:The largest deer in South America

The South American Swamp Deer (scientific name: Blastocerus dichotomus), also known as the swamp deer, is the largest deer in South America.The South American Swamp Deer is solitary or lives in groups of less than 6, but this changes according to the season and specific circumstances. They do not fo...

Odocoileus hemionus

Odocoileus hemionus

Odocoileus hemionus,Mule Deer、Black-tailed Deer、Cedros Island Mule Deer、Cedros Island Black-tailed Deer

Features:It is named after its mule-like ears.

Mule Deer (scientific name: Odocoileus hemionus) is also known as Mule Deer, Black-tailed Deer, Cedros Island Mule Deer, Cedros Island Black-tailed Deer, and has 11 subspecies. It is named after its mule-like ears and is also called black-tailed deer.Mule deer are like nomads, following water and gr...

Odocoileus virginianus

Odocoileus virginianus

Odocoileus virginianus,White-tailed Deer,Key Deer,Key Deer Toy Deer, Cariacú, Venado Cola Blanca,Virginia Deer

Features:The white-tailed deer gets its name because its tail is lifted up when it runs, and the white base of the tail is visible.

White-tailed Deer (scientific name: Odocoileus virginianus) English White-tailed Deer, Key Deer, Key Deer Toy Deer, Spanish Cariacú, Venado Cola Blanca, is a large herbivore of the Cervidae family and the genus Odocoileus.White-tailed deer are the most vigilant and timid species among deer. They ty...

Capreolus pygargus

Capreolus pygargus

Capreolus pygargus,Siberian Roe Deer,Eastern roe deer,Siberian Roe,Oriental roe deer, roe deer, dwarf deer, roe deer

Features:Has a strong "curiosity", known as the silly roe deer

Siberian roe deer (scientific name: Capreolus pygargus) is also known as Siberian Roe Deer, Eastern roe deer, and Siberian Roe. It has four subspecies. It is one of the two species in the genus Capreolus, Cervidae, and is listed alongside the western roe deer.Siberian roe deer are alert, with keen s...

Capreolus capreolus

Capreolus capreolus

western roe deer,Capreolus capreolus,European roe deer

Features:Only male roe deer have horns, which are short and straight.

Western roe deer (English: western roe deer, scientific name: Capreolus capreolus), also known as European roe deer, mainly lives in mountains and is rarely seen in plains or islands. There are 5 subspecies.The western roe deer is often active in the evening. It mainly moves in and out of the forest...

Rangifer tarandus

Rangifer tarandus

Rangifer tarandus,Reindeer

Features:Both males and females have horns, and the complex branching of the horns is an important feature of their appearance.

Reindeer (scientific name: Rangifer tarandus) is called Reindeer in foreign language. There are 17 subspecies. Also known as horned deer, it is the only animal under the genus Reindeer in the family Cervidae.The most amazing behavior of reindeer is the annual migration of hundreds of kilometers. As...

Muntiacus vaginalis

Muntiacus vaginalis

Muntiacus vaginalis,Barking Deer、Indian Muntjac、Indian Red Muntjac、Northern Red Muntjac,Northern Red Muntjac

Features:

The scientific name of Indian Red Muntjac is Muntiacus vaginalis. Its foreign names include Barking Deer, Indian Muntjac, Indian Red Muntjac, and Northern Red Muntjac. Similar to the Yellow Muntjac, it will bark when in danger, so it is also called the Barking Deer. Except for the mating season, it...

Muntiacus truongsonensis

Muntiacus truongsonensis

Muntiacus truongsonensis,Annamite Muntjac、Annam Black Muntjac、Annamite Dark Muntjac、Pygmy Muntjac、Truongson Muntjac、Truong Son Muntjac

Features:One of the smallest muntjac species

The scientific name of the Truong Son Muntjac is Muntiacus truongsonensis, and its foreign names are Annamite Muntjac, Annam Black Muntjac, Annamite Dark Muntjac, Pygmy Muntjac, Truongson Muntjac, and Truong Son Muntjac. It was discovered in Truong Son, Vietnam and its surrounding areas in 1997. It...

Muntiacus rooseveltorum

Muntiacus rooseveltorum

Muntiacus rooseveltorum,Muntjac,Roosevelts' Barking Deer,Roosevelt Muntjac, Barking Muntjac

Features:

Roosevelt's Barking Deer is a subspecies of the Barking Deer, and was proposed as a separate species by the Field Museum in 1929 on a hunting expedition led by Theodore (JNR) and Kermit Roosevelt. The specimen provided by the museum was slightly larger than the common small muntjac, and DNA test...

Muntiacus putaoensis

Muntiacus putaoensis

Muntiacus putaoensis,Leaf Muntjac,Leaf Deer,Fossil muntjac

Features:The smallest muntjac in the world

Leaf Muntjac (scientific name: Muntiacus putaoensis) is also known as Leaf Muntjac and Leaf Deer. It has no subspecies and is the smallest muntjac in the world.Leaf Muntjac is solitary. This is consistent with the view that leaf muntjacs represent an ancient group of muntjacs. Ancient muntjacs were...

Muntiacus puhoatensis

Muntiacus puhoatensis

Muntiacus puhoatensis,Puhoat Muntjac,Przewalski's muntjac

Features:A newly discovered species

The scientific name of the Puhoat Muntjac is Muntiacus puhoatensis, and its foreign name is Puhoat Muntjac. It is a newly discovered species that is only distributed in the Pu hoat area of Vietnam, which borders Laos. Some scientists also believe that the Puhoat Muntjac and the Luo Muntjac are the s...

Muntiacus montanus

Muntiacus montanus

Muntiacus montanus,Sumatran Muntjac

Features:

The scientific name of the Sumatran Muntjac is Muntiacus montanus, and its foreign name is Sumatran Muntjac. It is a solitary animal with timid and cautious habits. It mostly forages at night or in the early morning and dusk, and hides in the bushes to rest during the day. When frightened, it can ma...

Muntiacus vuquangensis

Muntiacus vuquangensis

Muntiacus vuquangensis,Giant Muntjac, Giant Barking Deer

Features:The largest muntjac species in the world

The Vietnamese giant muntjac, scientifically known as Muntiacus vuquangensis, is a species of muntjac. It is the largest muntjac species in the world and was discovered in Ha Tinh Province, Vietnam and central Laos in 1994. The giant muntjac is a solitary animal with timid habits. It mostly forages...

Muntiacus atherodes

Muntiacus atherodes

Muntiacus atherodes,Bornean Yellow Muntjac、Bornean Yellow Muntjack,Tufted Deer

Features:The length of the antlers is only 7 cm, which is smaller than that of ordinary muntjacs.

The scientific name of the Bornean Yellow Muntjac is Muntiacus atherodes, and its foreign names are Bornean Yellow Muntjac and Bornean Yellow Muntjack. It has only been recognized as an independent species in recent years. Its antlers are only 7 cm long, which is smaller than those of ordinary muntj...

Muntiacus reevesi

Muntiacus reevesi

Muntiacus reevesi,Chinese Muntjak,Formosan Reeves' Muntjac、Reeve’s Muntjac、Reeves's Muntjac,Mountain barking deer, dog muntjac, horned muntjac, yellow muntjac, mountain muntjac

Features:The head is bright brown, the body hair is tan, and the nape of the neck is darker and dark brown.

Muntiacus reevesi (scientific name: Chinese Muntjak, Formosan Reeves' Muntjac, Reeve's Muntjac, Reeves's Muntjac), has three subspecies and is a small deer animal.The activity pattern of the small muntjac is similar to that of the red muntjac. It is an animal active during the day, and i...

Muntiacus muntjak

Muntiacus muntjak

Muntiacus muntjak,Bornean Red Muntjac,Indian muntjac, Borneo red muntjac, red muntjac, southern red muntjac, barking deer, yellow muntjac

Features:The length of the horn handle is the longest among muntjacs

Red Muntjac (scientific name: Muntiacus muntjak) is also known as Bornean Red Muntjac. It has 17 subspecies and is the largest species among muntjacs.Red muntjacs often appear around the forest, especially in the morning and evening, and are less active during the day. Their calls are rarely heard f...

Muntiacus feae

Muntiacus feae

Muntiacus feae,Fea's Muntjac、Forest muntjac,Wood muntjac, black muntjac, Fischer's muntjac

Features:The shape of the nasal bone is long in the middle and short on both sides, forming an inverted "V" shape.

Fea's Muntjac (scientific name: Muntiacus feae) is also known as Fea's Muntjac and Forest muntjac in foreign languages. It has no subspecies.Philippine muntjacs often move alone, and when startled, they often swim across streams and hide in the forest on the other side. When frightened by pr...

Dama dama

Dama dama

Dama dama,Fallow Deer

Features:One of the most beautiful deer in Europe

Fallow Deer (scientific name: Dama dama) has two subspecies.Male fallow deer in estrus will expand their territory, and female fallow deer will join them. The population can reach up to 150 at most. They like to live in groups and are particularly good at running. Fallen deer herds have no concept o...

Dama mesopotamica

Dama mesopotamica

Dama mesopotamica,Mesopotamian Fallow Deer、Persian Fallow Deer,Mesopotamian fallow deer, Mesopotamian deer

Features:The Persian fallow deer is larger than the fallow deer, and has larger antlers, but less palmate.

The scientific name of the Persian fallow deer is Dama mesopotamica, and its foreign names are Mesopotamian Fallow Deer and Persian Fallow Deer. They were introduced to Cyprus in the Neolithic Age. They are found in many places, including Kirokitia. There are Greek records in 200 that they swam acro...