Final answer:
The three potential hominin genera from the early Pliocene are Ardipithecus, Sahelanthropus, and Orr Orin, with Ardipithecus being the youngest and showing signs of bipedalism.
Step-by-step explanation:
The three potential hominin genera in the early Pliocene are Ardipithecus, Sahelanthropus, and Orr Orin. Ardipithecus is the youngest of these, with species such as A. ramidus and A. Kadamba, and has been demonstrated to be bipedal, with specimens dating up to 5.6 MYA. The status of the genus Ardipithecus as a human ancestor, however, is still uncertain. Although the genus Homo, which includes species like H. habilis and the earlier-discovered Homo autogenesis, appeared later, between 2.5 and 3 million years ago, it is not considered one of the genera from the early Pliocene.