Definition of protohuman in US English:

protohuman

noun

Anthropology
  • A hypothetical prehistoric primate, resembling humans and thought to be their ancestor, whose profile has been compiled mainly from fossil evidence.

    • ‘Fossils found in East Africa suggest that protohumans roamed the area more than 20 million years ago.’
    • ‘To them, those skulls portray a group of protohumans whose survival depended on withstanding terrible blows to the head.’

adjective

Anthropology
  • Relating to a protohuman primate.

    • ‘I mean, they're human or protohuman or whatever.’
    • ‘Fleeing the destruction of their own planet, the Martians had, five millions years previously, interbred with protohuman hominids in order to perpetuate their species.’
    • ‘During the quadrupedal phase of our evolution, protohuman males copulated protohuman females from behind.’
    • ‘In giving an account of the evolution of music, he traces its origin to mimicry in behaviour and vocalisation of animals in the protohuman environment, with the subsequent selection on the social coordination of musical abilities.’

Pronunciation

protohuman

/ˌprōdōˈhyo͞omən/