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Ovis dalli
Ovis dalli, Thinhorn Sheep,Dall's Sheep,Stone’s sheep,Muflón de Dall
Dall's argali (scientific name: Ovis dalli) English Thinhorn Sheep, Dall's Sheep, Stone's sheep, Spanish Muflón de Da···
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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:
Perissodactyla: including horses, rhinos, tapirs, etc., with an odd number of toes (the middle toe bears weight).
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)
| Family | Example Genera/Species | Notes |
|---|---|---|
| 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)
| Family | Example Genera/Species | Notes |
|---|---|---|
| Suidae (Pigs) | Sus (wild boar, domestic pig), Phacochoerus (warthog) | Omnivorous, often with prominent canines; Old World distribution. |
| Hippopotamidae (Hippos) | Hippopotamus amphibius | Semi-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 antelopes | Extremely successful and diverse herbivores in Africa, Eurasia, and North America. |
Whales (Cetacea, included in Cetartiodactyla)
| Family | Example Genera/Species | Notes |
|---|---|---|
| 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.
Species directory
Browse Mammals
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Ovis canadensis
Ovis canadensis）,Bighorn Sheep,Mountain Sheep,Mouflon D'Amérique,Mouflon Du Canada,Mouflon Pachycère, Borrego Cimarrón,Carnero Del Canadá,Carnero Salvaje
Canadian Bighorn Sheep (scientific name: Ovis canadensis) is called Bighorn Sheep, Mountain Sheep in English, Mouflon D'Améri···
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Oreamnos americanus
Oreamnos americanus,Mountain Goat,Rocky Mountain Goat
Snow sheep (scientific name: Oreamnos americanus) is also known as Mountain Goat and Rocky Mountain Goat. There is no subspecies.T···
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Capricornis sumatraensis
Sumatran serow, Ming mane sheep, mountain donkey, rock donkey, four-legged beast, Pegasus, shepherd
Capricornis sumatraensis (English: Mainland Serow, Serow, Spanish: Serau de Sumatra, German: Südlicher Serau), has three subspeci···
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Capricornis crispus
Capricornis crispus,Japanese Serow
Japanese Serow (scientific name: Capricornis crispus) is also known as Japanese Serow, and has no subspecies. As one of Japan'···
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Nilgiritragus hylocrius
Nilgiritragus hylocrius,Nilgiri Tahr
The Nilgiri Tahr sheep (scientific name: Nilgiritragus hylocrius) has a foreign name of Nilgiri Tahr and has no subspecies.Nilgiri···
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Arabitragus jayakari
Arabitragus jayakari, Arabian Tahr，Wa’al Al ‘arabi
Arabian Tahr (scientific name: Arabitragus jayakari) English: Arabian Tahr, Arabic: Wa’al Al ‘arabi, no subspecies. Arabian Tahr···
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Capra walie
Capra walie
The Walia Ibex (Capra walie) has no subspecies. Walia Ibex are active or feeding only in the early morning and late evening. They ···
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Capra pyrenaica
Iberian ibex, Iberian wild goat, Spanish goat, Iberian wild goat, Alpine wild goat
Spanish ibex (scientific name: Capra pyrenaica) is called Iberian Wild Goat, Iberian Ibex in English, Bouquetin Ibérique in Frenc···
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Capra nubiana
Capra nubiana
Nubian ibex (scientific name: Capra nubiana) English Nubian Ibex, Spanish Íbice Núbico, Arabic Wa'al, German Nubischer Stein···
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Capra ibex
Ibex, Alpine Ibex, Capra Ibex, Alpine Ibex
Ibex (scientific name: Capra ibex) English Alpine ibex, French Bouquetin des Alpes, Spanish Íbice de los Alpes, German Alpenstein···
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Capra falconeri
Capra falconeri,spiral-horned goat
Markhor (scientific name: Capra falconeri) is called Markhor in English, Markhor and Schraubenziege in German, and has three subsp···
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Capra cylindricornis
Capra cylindricornis
Eastern Caucasian ibex (scientific name: Capra cylindricornis) English Eastern Tur, East Caucasian Tur, Spanish Tur oriental, Russ···
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Capra caucasica
Capra caucasica
West Caucasian ibex (scientific name: Capra caucasica) English Western Tur, Tur, West Caucasian Tur, Spanish Tur occidental, Germa···
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Capra hircus
Summer sheep, black sheep, domestic goat
Goats (scientific name: Capra hircus) are one of the earliest domesticated livestock by humans.Modern goats are domesticated from ···
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Capra aegagrus
Capra aegagrus,Persian Ibex
Wild goats (scientific name: Capra aegagrus) are also known as Wild Goat and Bezoar in foreign languages. There are 7 subspecies.I···
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Ammotragus lervia
Ammotragus lervia,Bearded sheep, Barbary sheep, Berber sheep
The scientific name of the Barbary Sheep is Ammotragus lervia, which is also known as Aoudad, Barbary Sheep, Uaddan in English, Mo···
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Addax nasomaculatus
Addax nasomaculatus (scientific name: Addax nasomaculatus) has two subspecies.Addax has a strong gregarious nature. It lives in sm···
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Oryx leucoryx
Oryx leucoryx,Arabian Oryx, Arabian Oryx, Arabian Oryx
Arabian Oryx (scientific name: Oryx leucoryx) is called Arabian Oryx in foreign language. It has no subspecies and is the smallest···
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Oryx gazella
Oryx gazella,Gemsbok,Gemsbok
South African Oryx gazella (scientific name: Oryx gazella) is also known as Gemsbok in foreign languages. It has 4 subspecies.Sout···
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Oryx dammah
Oryx dammah,Scimitar-horned oryx,Scimitar-horned oryx, white oryx, white oryx, scimitar-horned oryx, scimitar-horned oryx
Scimitar-horned oryx (scientific name: Oryx dammah) is called Scimitar-horned oryx in English. It has no subspecies. It was discov···
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Oryx beisa
East African Gemsbok, Oryx oryx, East African Gemsbok
East African Oryx (scientific name: Oryx beisa) English Beisa Oryx, French Oryx Beisa, German Eritrea-Spiessbock, Somali Be'id···
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Hippotragus niger
Hippotragus niger,Sable Antelope
Sable Antelope (scientific name: Hippotragus niger) is also known as Sable Antelope in English. There are 5 subspecies.Sable Antel···
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Hippotragus leucophaeus
Hippotragus leucophaeus，Bluebuck
The scientific name of the bluebuck is Hippotragus leucophaeus, and its foreign name is Bluebuck. It is an extinct antelope and th···
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