Final answer:
The earliest 'possible hominin' discovered to date is Sahelanthropus tchadensis, also known as 'Toumai'. It was found in Chad, West Africa, in 2002, and its cranial capacity was equivalent to that of a modern chimpanzee. Its discovery was surprising because it occurred outside of the traditional East African region.
Step-by-step explanation:
The earliest 'possible hominin' discovered to date is Sahelanthropus tchadensis, also known as 'Toumai'. It was found in Chad, West Africa, in 2002 and is estimated to have lived approximately 7 million years ago. Sahelanthropus had a cranial capacity of 350 cubic centimeters, equivalent to that of a modern chimpanzee. The location of its discovery was surprising because it was found outside of the traditional East African region where hominin fossils were typically found.
Sahelanthropus is considered a possible early hominin because it exhibits a mix of primitive and evolved characteristics. However, it is not confirmed if it is a direct ancestor of modern humans. Genetic studies indicate that the divergence between humans and chimpanzees happened between 5 and 7 million years ago, which overlaps with Sahelanthropus' estimated age.
Keywords: earliest 'possible hominin', nickname hominin, cranial capacity, modern chimpanzee, discovery surprising