Paranthropus aethiopicus represents one of the earliest members of this genus Paranthropus, which means "beside man".  This name infers that paranthropines were not direct ancestors of modern humans. 

Fossil remains found in West Turkana (Kenya) and Lower Omo (Ethiopia) suggest that P. aethiopicus has a relatively small cranial capacity at approximately 410 cc and a prognathic face. To date, no post-cranial P. aethiopicus material has been identified.  As with other paranthropines, P. aethiopicus derived features include a sagittal crest, a flattened face, and very large postcanine dentition. The advent of these novel features, earlier than other Paranthropus species suggests that P. aethiopicus may represent an early state of paranthropine evolution that is ancestral to the east African Paranthropus boisei.

The type specimen for P. aethiopicus is a fragmentary mandible known as Omo 18-1967-18 from Ethiopia that dates to 2.5 million years ago.  The “Black Skull”, or KNM-WT 17000, is the most famous P. aethiopicus fossil, which was found in West Turkana (Kenya) and dates to approximately 2.5 million years ago.