The australopithecines were the first hominins to be found that we know for certain came after the human-chimpanzee split. The others that we’ve covered yet are still teetering on the edge of the split between humans and chimpanzees. Australopithecus anamensis is the first of this genus, and it was 4 million years old. Au. anamensis was probably the ancestor of Au. afarensis, or ‘Lucy’, arguably one of the most famous fossils ever, but the two species coexisted for 100,000 years, so scientists aren’t sure what happened here. There are also signs that showed that Au. anamensis was a descendant of Ardipithecus ramidus.
Australopithecines and their descendants had thickset and robust skulls with structures called sagittal crests on their skulls. Sagittal crests are used to anchor exceptionally large and strong jaw muscles and their presence signifies that the animal ate a lot of tough, hard foods. Australopithecines would later give rise to the Paranthropus genus, which had even more thickset skull and had huge sagittal crests and front-jutting faces.
Australopithecus anamensis is one the least known australopithecines, but it gives us a lot of context as to how our ancient cousins evolved.
Anay Ganesh 