Field teams working at Woranso-Mille in the Afar Rift found a set of foot bones in 2009 that are about 3.4 million years old. The bones, nicknamed the Burtele Foot, have now been associated with Australopithecus deyiremeda. The work appears in the journal Nature and had outside funding support.
Paleoanthropologists decided not to name a species from the foot alone initially, but returning to the site over several years produced more fossils. The team links the Burtele Foot to A. deyiremeda after these additional finds.
University researchers sampled teeth from the site to study diet. Isotope analysis shows A. deyiremeda relied on foods from trees and shrubs, while A. afarensis ate a broader mix that included tropical grasses and sedges. A juvenile jaw with baby and developing adult teeth suggests similar growth patterns between the species.
Anatomically, the Burtele Foot kept an opposable big toe and had long, flexible toes for climbing. When walking on two legs, A. deyiremeda probably pushed off with the second toe. Scientists say these fossils show early human ancestors used different walking styles and diets to live together.
Difficult words
- paleoanthropologist — scientist who studies ancient human remainsPaleoanthropologists
- associate — connect one thing to another in studyassociated
- fossil — preserved remains or traces of ancient organismsfossils
- isotope analysis — chemical test of remains to study diet
- juvenile — young individual not yet fully grown
- opposable — able to move against other digits for grasping
- sedge — a grass-like plant that grows in wetlandssedges
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How might different diets help two similar species live in the same area?
- What can scientists learn from a juvenile jaw about growth and development?
- Do you think an opposable big toe would help with tree climbing? Why or why not?
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