Casts of two key specimens (IMAGE) Proceedings of the National Academy of Sciences Caption Casts of two key specimens of Paranthropus aethiopicus (left; "Black Skull"; KNM-WT-17000) and P. boisei (right; "Zinj", OH 5) Credit Image credit: Zeresenay Alemseged Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.