Artiodactyla

Artiodactyls are a large group of mammals that we often call even-toed ungulates.

These animals are special because they carry their weight on an even number of toes. Usually, they use their third and fourth toes to walk. These toes often grow into a hard hoof. This is different from perissodactyls, which walk on an odd number of toes. Many artiodactyls are herbivores that eat plants. They have special stomach chambers to help them digest plant cellulose.

This way of eating helps them get energy from tough plants. Some members, like pigs, are omnivores and eat both plants and meat.

How these animals live and eat can vary a lot.

Most land-based artiodactyls are herbivores, such as cattle, sheep, and goats. Others, like the camel or the llama, live in different environments. Some animals in this group are even more surprising. Scientists found that whales, dolphins, and porpoises belong to this branch too.

These ocean animals are called cetaceans. They are most closely related to hippopotamuses. Because they are so different, some scientists use a new name, Cetartiodactyla, to include both the land and sea animals. This name helps show they all share a common history.

We can look back in time to see where they began.

The oldest fossils of even-toed ungulates are about 53 million years old. These fossils come from the early Eocene period. They were found in Europe, Asia, and North America at the same time. This makes it hard to know exactly where they first started. The very first artiodactyls belonged to a family called Diacodexeidae.

One famous member was called Diacodexis. These were small animals, sometimes only as big as a hare. They had slim bodies, long tails, and legs that were longer in the back than the front.

Many different kinds of artiodactyls have lived throughout history.

Some were very large, like the Entelodonts. These animals lived from the middle Eocene to the early Miocene. They had stocky bodies and massive heads with bony bumps on their jaws. Another group called Anthracotheres lived from the middle Eocene to the Pliocene.

These animals were pig-like and are thought to be the ancestors of modern hippos. Hippos themselves appeared later, in the late Miocene. They live in Africa and Asia but never lived in the Americas. Other groups, like the Merycoidodontidae, were camels that lived in North America until about 10,000 years ago.

Learning about these animals involves much more than just looking at bones.

In the 1990s, researchers began using molecular biology to study them. This means they look at the DNA, or the genetic code, inside living things. By comparing DNA, scientists proved that whales are related to even-toed ungulates.

They also found fossils in Pakistan that helped tell the story. These fossils, like Pakicetus, were about 48 million years old. These ancient whales had ankle bones that looked just like the ones in land animals. This discovery helped prove how a land animal could eventually become a whale.