Ancestor of man who first stood erect was Australopithecus.

Australopithecus was a genus of hominids that lived in Africa from around 4 million to 2 million years ago. They were the first known hominids to walk upright on two legs, a trait known as bipedalism.

Evidence of bipedalism in Australopithecus comes from the shape of their pelvis and thigh bones, which suggest that they walked on two legs. They also had a curved spine, which is another adaptation to bipedalism.

Australopithecus was a small-brained species, with a brain size of around 400-500 cubic centimeters. They had a more ape-like face, with a protruding jaw and a flattened nose. They also had long arms and curved fingers, which were adaptations for climbing trees.

There were several species of Australopithecus, including Australopithecus afarensis, which is the species that the famous fossil Lucy belongs to. Other species include Australopithecus africanus, Australopithecus boisei, and Australopithecus sediba.

Australopithecus is considered to be an important ancestor of modern humans because it was the first hominid to walk upright on two legs. This adaptation allowed them to move more efficiently across the ground and freed up their hands for other tasks, such as carrying food or tools.

In conclusion, Australopithecus was the ancestor of man who first stood erect. They were the first hominids to walk upright on two legs, which was a crucial adaptation that allowed them to survive and evolve into the modern humans we are today.