Horses have undergone all sorts of evolutionary changes, which is why the recent discovery of a previously unknown, 4.4 million year-old species of horse, Eurygnathohippus woldegabriel (named for geologist Giday WoldeGabriel), will help add to the overall picture, according to Science World News.

"This horse is one piece of a very complex puzzle that has many, many pieces," said Scott Simpson, who co-authored research on the ancient fossil.

The complexity of those pieces along with more advanced technology might explain why Simpson and colleagues are only publishing their research recently after discovering the fossil's first pieces in 2001, according to the press release.

About the size of a small zebra, the horse fossil was found in the Ethiopian desert, which wasn't arid over 4 million years ago but filled with grasslands and woods, and home to a wide variety of animals. To evade a biologically diverse set of predators like sabre tooth cats, lions, and hyenas, the species evolved longer legs from its forbearers six to ten million years ago, according to the release. The adaptation also helped them travel long distances to feed on available grass.

In addition to learning more about the evolution of horses, the discovery -- and ones like it -- helped scientists gain a better understanding of ancient environments. For example, they could tell the horse ate grass just by analyzing its teeth. Thus, they gained further information on the time period's grasslands.

"Grasses are like sandpaper," Simpson said. "They wear the teeth down and leave a characteristic signature of pits and scratches on the teeth so we can reliably reconstruct their ancient diets."

Fossil records indicated that proceeding horse species had even longer legs and faces for further adaptations to the grassland, according to the release.