Two important reasons are listed here:
- Pre-australopithecines show evidence of bipedalism but they lived in forested areas
- Ardipithecus ramidus is a human ancestor that lived in a wooded environment approximately 4.2 to 4.5 million years ago
The savanna hypothesis states that early hominid traits were selected in response to increased aridity conditions and the emergence of savanna landscapes (i.e., open grasslands), as forests receded. This hypothesis enables us to understand better the evolution of bipedalism.
Pre-Australopithecines represent the oldest hominids that date from at least 7 to 4.4 million years ago (mya), depending on the species. Pre-australopithecines show evidence of bipedalism (and/or dentition similar to the later hominins who exhibit bipedalism), but it has been shown that they lived in forested areas. Therefore, this observation contradicts the savanna hypothesis which states that bipedalism evolved as an adaptation to the savanna.
Ardipithecus ramidus is a human ancestor dating to between 4.5 and 4.2 mya. The Ardipithecus ramidus fossils were discovered in Ethiopia alongside faunal remains, thereby indicating they lived in a wooded environment. In consequence, Ardipithecus ramidus fossils contradict the open savanna explanation for the origin of bipedalism.
Learn more about this topic here:
https://brainly.com/question/17078398
