Scientists have uncovered a new species of horse drawn from 4.4 million-year-old fossil-rich deposits in Ethiopia.
The species, Eurygnathohippus woldegabrieli, was about the size of a small zebra, had three-toed hooves and grazed the grasslands of the Afar Region, one of the lowest points in Africa. The findings, published in the Journal of Vertebrate Paleontology, describes how the new species could explain missing gaps in horses' evolutionary history.
"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 co-author of the research, said in a statement.
Researchers found teeth and bone fossils belonging to the prehistoric horse in 2001. The species was among a variety of animals that roamed Earth alongside the human ancestor, Ardipithecus ramidus, commonly called Ardi.
"The fossil search team spreads out to survey for fossils in the now arid badlands of the Ethiopian desert.," Simpson said. "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."
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A year later the team discovered another bone, a connecting shaft, which indicates the horse was a strong runner. Researchers also determined the horses had long legs, allowing them to cover great distances and escape predators like lions, sabre-tooth cats and hyenas. Tooth analyses also revealed the horse’s diet consisted of grass.
"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."
The new species, which had grazing habits akin to modern zebras, wildebeests and white rhinoceroses, was named after Giday WoldeGabriel, a geologist at Los Alamos National Laboratory who studied the Ethiopian Rift system where some of the oldest human ancestor fossils have been found.