Final answer:
Michel Brunet, a French paleoanthropologist, discovered Sahelanthropus tchadensis in 2002. This specimen, nearly 7 million years old, contributes to the understanding of human evolutionary history, yet its exact place in our ancestral tree is still debated.
Step-by-step explanation:
The person who discovered Sahelanthropus tchadensis was French paleoanthropologist Michel Brunet. His team found a complete cranium of Sahelanthropus in Chad in 2002. The specimen, informally known as "Toumai," is significant for its age, dating to nearly 7 million years ago, which is around the time when humans and chimpanzees are thought to have diverged according to molecular data. Although its cranial capacity is similar to a chimpanzee's, and it possesses a very large brow ridge, the location of the foramen magnum led to suggestions that Sahelanthropus tchadensis might stand closer to the common ancestor of humans and chimpanzees than other early hominins. However, this classification and its role in human evolution remain a subject of debate among scientists.