Final answer:
Ardipithecus ramidus is approximately 4.4 million years old and belongs to the Pliocene era. It exhibits bipedal traits such as a forward position of the foramen magnum and small upper arm bones. Other traits include thin dental enamel, reduced canines, and an opposable big toe.
Step-by-step explanation:
The geological age of Ardipithecus ramidus is approximately 4.4 million years ago (MYA). Ardipithecus ramidus is the first discovered hominin species to be dated to the Pliocene era. It was found in Ethiopia in 1992 and is believed to have been bipedal based on the forward position of the foramen magnum and the small size of its upper arm bones. Additionally, Ardipithecus possesses various traits such as thin dental enamel, reduced canines, and an opposable big toe.