Researchers working in Uganda say they have unearthed the well-preserved fossil skull of an ancient primate.

The 20 million-year-old specimen comes from the site of an extinct volcano in Uganda's north-east Karamoja region.

The scientists say preliminary analysis showed the tree-climbing herbivore was roughly 10 years old when it died.

The skull is about the same size as that of a chimp, but its brain was smaller....