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Ungulate

life science Maturity 5-7 Next article →

Ungulates are a diverse group of mammals characterized primarily by having hooves. The term comes from the Late Latin word "ungula," which means a small nail or hoof.

Equus quagga (white background)
Equus quagga (white background)

Most terrestrial ungulates use the hard, hoofed tips of their toes to support their body weight. This physical structure allows them to stand and move efficiently across various landscapes. While most people associate ungulates with land animals, the group actually includes marine mammals too.

Cladogram of Cetacea within Artiodactyla (Camelus bactrianus)
Cladogram of Cetacea within Artiodactyla (Camelus bactrianus)

These animals are central to many ecosystems because of how they eat and move.

Living ungulates are divided into two distinct biological orders: Perissodactyla and Artiodactyla. Perissodactyla are known as odd-toed ungulates because of their toe structure. This order includes horses, rhinoceroses, and tapirs.

Rhino white background
Rhino white background

Artiodactyla are known as even-toed ungulates. This group is much larger and includes cattle, antelope, pigs, giraffes, camels, sheep, deer, and hippopotamuses.

Interestingly, cetaceans like whales and dolphins are also classified as artiodactyls. Even though they lack hooves, they descended from early artiodactyl ancestors.

Bluewhale877
Bluewhale877

This classification shows how much animals can change over millions of years.

Most ungulates are herbivorous, meaning they eat plants. To survive on tough vegetation, many use specialized gut bacteria to digest cellulose. Cellulose is the tough material found in plant cell walls.

Tapir white background
Tapir white background

However, not all ungulates follow this rule. Several species of pigs are omnivorous, meaning they eat both plants and meat. The extinct entelodonts were also omnivorous.

Pecari tajacu white background
Pecari tajacu white background

Some members, like modern cetaceans and the extinct mesonychians, are actually carnivorous. This dietary variety shows how the group has adapted to different food sources.

Scientific understanding of these animals has changed significantly due to new technology. In the past, scientists used a broad group called "Ungulata" to include many different mammals. This old group included elephants, aardvarks, and sea cows.

Hippopotamus - 04
Hippopotamus - 04

However, molecular data—the study of DNA—showed this grouping was polyphyletic. This means the animals in that group did not all share a single common ancestor. In 2001, true ungulates were reclassified into the clade Euungulata.

This new classification placed them within the larger clade Laurasiatheria. Meanwhile, groups like elephants and aardvarks were moved to a different clade called Afrotheria.

The evolutionary history of ungulates stretches back millions of years. One of the earliest known members might be the tiny Protungulatum. This mammal lived 66 million years ago, coexisting with the last non-avian dinosaurs.

Recherches pour servir à l'histoire naturelle des mammifères (Pl. 80) (white background)
Recherches pour servir à l'histoire naturelle des mammifères (Pl. 80) (white background)

Perissodactyls began to diversify and spread across continents about 55 million years ago. Early horses, belonging to the family Equidae, appeared in the early Eocene about 54 million years ago. These early ancestors were only the size of a fox. They had four toes on their front feet and three on their hind feet.

Zebras Ngorongoro Crater
Zebras Ngorongoro Crater

Over time, they developed teeth better suited for grinding tough grasses.

Some extinct ungulates were truly massive or unusual in form. The Paraceratherium was an enormous Asian rhinoceros. It reached a size that was more than twice the weight of an elephant.

There were also the desmostylians, which were large amphibious animals. They lived near the ocean and had unique teeth that looked like clusters of pipes or volcanoes.

The deer of all lands (1898) Hangul white background
The deer of all lands (1898) Hangul white background

In South America, two other orders called Notoungulata and Litopterna once thrived. These animals became extinct at the end of the Pleistocene, around 12,000 years ago. This shows how environmental changes can impact even successful groups.

Understanding ungulates helps scientists study convergent evolution. This happens when different species develop similar traits independently. For example, the extinct Australian marsupial Chaeropus developed hooves similar to artiodactyls.

Even though they are not closely related, they both found that hooves were useful. This concept connects ungulate biology to the broader study of how life adapts to its environment. By studying their teeth, bones, and DNA, we learn how animals transform to fit their worlds.

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🖼️ Images & Media (44)
File:Zebras Ngorongoro Crater.jpg
Zebras Ngorongoro Crater.jpg
File:Diceros bicornis.jpg
Diceros bicornis.jpg
File:Elaphurus davidianus 001.jpg
Elaphurus davidianus 001.jpg
File:Hippopotamus - 04.jpg
Hippopotamus - 04.jpg
File:Bluewhale877.jpg
Bluewhale877.jpg
File:Comdolph.jpg
Comdolph.jpg
File:Equus quagga (white background).jpg
Equus quagga (white background).jpg
File:Tapir white background.jpg
Tapir white background.jpg
File:Rhino white background.jpg
Rhino white background.jpg
File:Cladogram of Cetacea within Artiodactyla (Camelus bactrianus).png
Cladogram of Cetacea within Artiodactyla...
File:Pecari tajacu white background.jpg
Pecari tajacu white background.jpg
File:Recherches pour servir à l'histoire naturelle des mammifères (Pl. 80) (white background).jpg
Recherches pour servir à l'histoire...

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