This image provided by the Cleveland Museum of Natural History shows a bone fragment from a 3.4-million-year-old partial foot recovered during an excavation in Ethiopia. It is a significant discovery because it demonstrates there was more than one pre-human species living in East Africa between three and four million years ago, each with its own method of moving around. The researchers say they do not have enough remains to identify the species of hominin, or human ancestor, from which the right foot came. "This is just another window into solving the problem of how we got from a primitive foot to the modern human foot," said Bruce Latimer of Cleveland's Case Western Reserve University, who helped discover the fossil remains. Scientists don't yet know because no skull or teeth have been recovered to make a determination. Image caption The eight elements are all from the forefoot 
 
 The other creature was the famous "Lucy" animal (Australopithecus afarensis), whose remains were first identified in the Afar in the 1970s. These were arranged such that the foot could push off, or toe-off - something only humans do as they walk, and something flat-footed apes cannot achieve. Her big toe was aligned with the other four digits of the foot, and she had a human-like arch that allowed for very efficient locomotion. The fossils indicate it had no arch and the big toe was opposed to the other digits, enabling the animal to grasp branches in a tree. But the fact this creature could and would walk on the ground is evidenced by the nature of the bone joints. ___ 
 
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– Lucy was not alone. Scientists have unearthed fossilized bones that they believe must have belonged to the foot of another pre-human species that walked upright around 3 million years ago, the AP reports. It's the first evidence of such a species during that era since the one made famous by the Lucy skeleton. This foot clearly comes from a different species, but like Lucy its foot was designed to both walk and grab tree branches, with an opposable toe. The bones were discovered in Ethiopia, and dated to 3.4 million years ago, according to the BBC. For now, scientists can't classify the creature further, because they haven’t found its skull. "We've kept digging," says the curator of the Cleveland Museum of Natural History. "We have a few isolated teeth, but that's all." Still, even this limited find "is really exciting," one London palaeoanthropologist says. "This new foot helps elucidate the process of how the bi-pedal foot evolved."