16 – Origin of specialized chewing apparatus
2.5 million years ago
The skull of Australopithecus africanus shows a series of critical adaptations towards a new form of mastication, or chewing. A. africanus has an arrangement of muscle attachments that puts greater force on the anterior (front) of the mouth, rather than primarily over the molars. They have anterior pillars, a structure of bone on either side of the nose, as a possible reinforcement for increased chewing force. It isn’t clear exactly what these individuals ate to require this reorganization.
Image credit Shutterstock.
Environmental and Climate Changes
Shifts to even more open and arid environments 3 to 2.5 Ma
Pleistocene glaciation 2.5 Ma