In 2009, paleoanthropologists discovered eight foot bones of an ancient human ancestor in 3.4-million-year-old sediments at the Woranso Mille paleontological site in the Afar Rift of Ethiopia. According to a new study, the fossil, dubbed “Burtele's foot,” belongs to a species of hominin called I don't say Australopithecus. This discovery provides further evidence that two species of hominins – I don't say Australopithecus And Australopithecus afarensis — coexisted at the same time and in the same region.
“When we found the leg in 2009 and announced it in 2012, we knew it was different from Lucy's species. Australopithecus afarensiswhich has been widely known since that time,” said Arizona State University professor Johannes Haile-Selassie.
“However, it is not common in our field to name species based on postcranial elements, so we were hoping that we would find something above the neck that was clearly related to the foot.
“The skull, jaws and teeth are typically the elements used to recognize species.”
“When the Burtel foot was announced, some teeth had already been found in the same area, but we weren't sure if the teeth were from the same sediment level.”
“Then, in 2015, scientists announced a new species, I don't say Australopithecusfrom the same area, but did not include the leg in this species, although some specimens were found very close to the leg.”
“Over the last 10 years, as we've gone back into the field and found more fossils, we now have specimens that we can confidently link to Burtele's foot and the species I don't say Australopithecus“
I don't say Australopithecushis foot is more primitive than the feet of Lucy's species, Australopithecus afarensis.
It retains an opposable thumb, which is important for climbing. But when on earth, I don't say Australopithecus walked on two legs and, most likely, pushed off with the second toe, and not the big toe, as we modern people do today.
“The presence of a stolen big toe Ardipithecus ramidus This was a big surprise because 4.4 million years ago there was still an early ape ancestor that retained the opposable big toe, which was completely unexpected,” Professor Haile-Selassie said.
“Then, 1 million years later, 3.4 million years ago, we find Burtele's foot, which is even more amazing.”
“This is the time when we see species like Australopithecus afarensis the members of which were completely bipedal with the big toe adducted.”
“This means that bipedalism—walking on two legs—appeared in different forms in these early human ancestors.”
“The idea of finding specimens like Burtele’s foot suggests that there were many ways to walk on the ground on two legs, and later there was not just one way.”
To get an idea of your diet I don't say AustralopithecusThe authors sampled eight of the 25 teeth found at the Burtele sites for isotope analysis.
The process involves cleaning the teeth, and only samples of the enamel need to be taken.
“I take a sample of the tooth using a drill and a very tiny (<1mm) drill—the same equipment that dentists use to work on your teeth,” said University of Michigan professor Naomi Levine.
“Using this drill, I carefully remove a small amount of powder. I store this powder in a plastic vial and transport it back to our laboratory for isotope analysis.”
“The results were unexpected: although Lucy's species had a mixed diet, feeding on C3 (tree and shrub resources) and C4 (tropical grasses and sedges) plants, I don't say Australopithecus used resources that are more relevant to C3.”
“I was surprised that the carbon isotope signal was so clear and so similar to the carbon isotope data from older hominins. Australopithecus ramidus And Australopithecus anamus“
“I thought the differences between diet I don't say Australopithecus And Australopithecus afarensis would be more difficult to identify, but isotopic data clearly shows that I don't say Australopithecus did not have access to the same range of resources as Australopithecus afarensiswhich is the earliest hominin shown to utilize grass-based C4 food resources.”
Another key analysis of the data was carefully establishing the age of the fossils and understanding the ancient environments in which ancient hominids lived.
“We did a tremendous amount of careful field work at Woranso Mill to determine how different layers of fossils relate, which is critical to understanding when and under what conditions different species lived,” said Case Western Reserve University professor Beverly Saylor.
In addition to the 25 teeth found in Burtel, the researchers also discovered the jaw of a 4.5-year-old teenager, which, judging by the anatomy of the teeth, clearly belonged to I don't say Australopithecus.
“In a juvenile hominin of this age, we were able to see clear evidence of a growth difference between the front teeth (incisors) and the back chewing teeth (molars), very similar to what is seen in living apes and other early australopiths such as Lucy's species,” said Arizona State University professor Gary Schwartz.
“I think the biggest surprise has been that despite our growing awareness of how diverse these early australopith species (i.e. early hominins) were—in size, diet, locomotor repertoire and anatomy—these early australopiths seem remarkably similar in the way they grew.”
A paper the findings were published this week in the journal Nature.
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Y. Haile-Selassie etc.. New findings shed light on diet and movement I don't say Australopithecus. Naturepublished online November 26, 2025; doi: 10.1038/s41586-025-09714-4
