The fossil skull was from a three-year-old bipedal primate that he named Australopithecus africanus. The first report was published in Nature in February 1925. Dart realised that the fossil contained a number of humanoid features, and so, he came to the conclusion that this was an early ancestor of humans....

The correct answer is option 'C': Australopithecus.

Australopithecus is considered to be the first ancestor of man whose fossils have been discovered. Let's explore the reasons why Australopithecus is considered the earliest ancestor of humans:

1. Australopithecus Fossils: Fossils of Australopithecus have been found in various parts of Africa, particularly in Ethiopia, Tanzania, and South Africa. These fossils provide evidence of hominins that existed between 4 and 2 million years ago.

2. Morphological Features: The skeletal remains of Australopithecus display a combination of ape-like and human-like traits. For example, they had a small brain size similar to that of apes, but their teeth and jaws resembled those of early humans. This combination of features suggests a transitional form between apes and humans.

3. Bipedalism: One of the key characteristics of Australopithecus is its ability to walk on two legs, known as bipedalism. Fossil footprints and bone structures indicate that Australopithecus walked upright, which is a defining trait of humans. Bipedalism allowed Australopithecus to free its hands for tool use and contributed to the development of other human traits.

4. Lucy: One of the most famous Australopithecus fossils is "Lucy," scientifically known as Australopithecus afarensis. Lucy's skeleton, dated to around 3.2 million years ago, provided crucial evidence for bipedalism and helped shape our understanding of human evolution.

5. Preceding Hominins: While Australopithecus is considered the earliest ancestor of humans whose fossils have been discovered, it is important to note that other hominins existed before Australopithecus. These include Sahelanthropus, Orrorin, and Ardipithecus, which are believed to be even more ancient hominins. However, their fossils are relatively scarce, making it challenging to draw definitive conclusions about their evolutionary significance.

In summary, Australopithecus is considered the first ancestor of man whose fossils have been discovered due to its morphological traits, particularly bipedalism, and the abundance of fossil evidence found in Africa. Its significance in understanding human evolution cannot be overstated.