Fossils Unveil the Ancient Origins of Horses and Rhinos in India

Scientists may have just managed to fill in some major gaps in the evolution of a group of animals that includes horses and rhinos. The researchers have uncovered new fossils from the edge of a coal mine in India, revealing new insights into this group of animals.

Modern horses, rhinos and tapirs all belong to a biological group called Perissodactyla, also known as "odd-toed ungulates." Animals in this order have an uneven number of toes on their hind feet and a distinctive digestive system. While researchers have found remains of these creatures as far back as the Eocene epoch about 56 million years ago, their earlier evolution has remained a mystery-until now.

The researchers uncovered a rich vein of ancient bones. Of these bones, more than 200 fossils belonged to an animal named Cambaytherium thewissi. Although little is known about this animal, researchers believe that it's about 54.5 million years old. Not only that, but it could serve as a window into what the common ancestor of Perissodactyla might have looked like.

"Many of Cambaytherium's features, like the teeth, the number of sacral vertebrae, and the bones of the hands and feet, are intermediate between Perissodactyla and more primitive animal," said Ken Rose, one of the researchers, in a news release. "This is the closest thing we've found to a common ancestor of the Perissodactyla order."

These new fossils don't only offer information about Perssodactyla, though; they also provide tantalizing clues about India's separation from Madagascar and eventual collision with the continent of Asia. Researchers believe that several groups of mammals that appear at the beginning of the Eocene might have evolved in India when it was isolated.

The findings reveal a bit more about the evolution of this group of animals and shed a bit more light on their common ancestor.

The findings are published in the journal Nature Communications.