Final answer:
The Negroid (African) skull refers to the skull of Paranthropus aethiopicus, displaying traits of both robust and gracile australopithecines.
Step-by-step explanation:
The Negroid (African) skull, specifically that of Paranthropus aethiopicus, displays characteristics of both robust and gracile australopithecines. This species, dated to about 2.5 MYA, was discovered in Ethiopia in 1967. It is sometimes referred to as the 'black skull.