Final answer:
Human ancestral hominins exhibited small jaws and teeth, a larger third molar, skull shape resembling H. erectus or H. habilis, a sagittal keel, bipedal and humanlike locomotion, and humanlike feet with arches and ankles.
Step-by-step explanation:
Human ancestral hominins display several key features:
- Small jaws and teeth: Hominins had smaller jaws and teeth compared to their ancestors.
- Third molar larger than other molars: This trait was found in australopithecines and some early Homo species.
- Skull shaped like H. erectus or H. habilis: The skull of ancestral hominins resembled the skulls of Homo erectus or Homo habilis.
- Sagittal keel: This small raised ridge on top of the skull, seen in H. erectus, is a distinguishing feature of ancestral hominins.
- Bipedal and humanlike locomotion: Hominins were adapted for bipedal walking with a human gait.
- Humanlike feet: Ancestral hominins had feet with arches and ankles similar to modern humans.