Answer: All of the following statements are true about Ardipithecus ramidus:
a) possessing thin tooth enamel
b) lacking any knuckle-walking adaptations
c) human-like lower limb proportions
d) lack of a canine diastema
Ardipithecus ramidus is an early hominid species that lived about 4.4 million years ago in Africa. It is considered to be one of the oldest known hominids and is considered a key transitional species between apes and humans. Some of the characteristics that distinguish Ardipithecus ramidus from other hominids and apes include thin tooth enamel, lack of knuckle-walking adaptations, human-like lower limb proportions, and a lack of a canine diastema (a space between the upper canine tooth and the incisor tooth). These features suggest that Ardipithecus ramidus was a bipedal species that may have had some degree of social complexity and may have used tools.