Final answer:
Sahelanthropus tchadensis, discovered by Michel Brunet, presents an atypical combination of primitive and more advanced traits that intrigue scientists about its role in human evolution. Its small cranial capacity and large brow ridge resemble ape-like features, while the position of its foramen magnum challenges assumptions about its locomotion.
Step-by-step explanation:
Sahelanthropus tchadensis, with its mixture of traits, has puzzled scientists regarding its position in the hominin lineage. Found by paleoanthropologist Michel Brunet, Sahelanthropus exhibits an unusual combination of characteristics. For instance, it has a cranial capacity similar to that of a chimpanzee at approximately 350 cubic centimeters, a significant brow ridge, and the location of the foramen magnum suggests a non-bipedal stance. However, these features contrast with some evidence of traits that could suggest bipedalism, seen in other early hominins. Sahelanthropus represents a crucial time in the evolutionary history, possibly existing around the time when humans and chimpanzees diverged.