Question

Approximately 2 million years ago the genus Australopithecus gave rise to a new genus, Homo. Today, we retain the genus as Homo sapiens. What important fossil evidence MOST likely helped scientists change the classification of those early human ancestors? A) opposable thumb B) teeth and skull size C) pelvis and leg bones D) spine alignment and foot size

Answer 1

There was two of the same question, but here is the answer again with a little more depth.

D - spine alignment and foot size.

It was only the late Australopiths that had an S-shaped spine. This allowed for them to be bipedal, that is, the ability to walk on two legs as we do. This is because the S-shaped spine allowed them to balance when they were standing. The late Australopiths also have shorter and less flexible toes. These smaller, but sturdier feet made pushing off the ground much easier - aiding in their bipedalism. 

Answer 2

The correct answer is B) teeth and skull size