09 – Hominin with opposable big toe
3.4 million years ago
In 2012, a team of researchers made a shocking discovery. They found a fossil now called the Burtele foot, a partial hominin foot found at the site Woranso-Mille in the Afar region of Ethiopia dated to 3.4 million years old. This fossil foot showed long toes and an abducted big toe—like other apes and only the earliest hominins. What makes the foot so intriguing is that the morphology of the Burtele foot is different from the foot of Australopithecus afarensis, a species that was also living in the same place and time. The Burtele foot shows us that some nonbiped hominin lineages must have persisted for much longer than we previously thought. It has not been assigned to any particular species, as it does not match the morphology of any known hominin species from the time. The difference in morphology suggests that there were at least two different modes of locomotion present in hominin species at the time.
Image credit: Yohannes Haile-Selassie.
Environmental and Climate Changes
Continued aridity, enhanced seasonality—Loss of forests and savanna expansion 4.4 Ma