4.4 Million-Year-Old Horse Fossil Discovered, May be A New Species

The fossil of a new horse species has been discovered from 4.4 million-year-old fossil-rich deposits in Ethiopia by a group of researchers.

It is as big as a zebra and has three-toed hooves. Evidence also suggests that the animal grazed on grasslands and shrubby woods in the Afar Region. Teeth and bone remains of the species were first discovered in 2001 in the same region. The fossil not only fills a gap in the evolutionary history of horses but can also help researchers document how old a fossil locality is. This fossil horse was among the diverse array of animals that lived in the same areas as the human ancestors,  Ardipithecus ramidus, commonly called Ardi.

"This horse is one piece of a very complex puzzle that has many, many pieces," Scott Simpson, professor of anatomy at Case Western Reserve's School of Medicine, and coauthor of the research said in the statement. "The fossil search team spreads out to survey for fossils in the now arid badlands of the Ethiopian desert. Among the many fossils we found are the two ends of the foreleg bone-the canon-brilliant white and well preserved in the red-tinted earth."

 Now, almost a year later the team has found part of the connecting shaft, which though split lengthwise, still showed the full length of the bone. Judging from the slender bone, it is clear that the species was a great runner like modern zebras. The teeth reveal that they grazed heavily on the grassy woodlands in the region.

Researchers also noted that the newly discovered horse species had longer legs than horses that lived 6 to 10 million years ago. This development of longer legs has helped modern horses run faster, fleeing lions and other predators and hunting hyenas. An analysis of the teeth fossil revealed that the species had adapted to grazing over time as their teeth were longer than ancestral horses. The isotopic composition of the enamel also confirms that the animal was a grass-eater. The bones clearly show that the horse was significantly different than horses that existed more than 5 million years ago.

The species has been named Eurygnathohippus woldegabrieli, after the geologist Giday WoldeGabriel. Researchers of the new project decided to name the species after the geologist because of his immense contribution in unraveling the geological complexities of the deposits in Ethiopia where fossils of some of our oldest human ancestors have been found.