Researchers working in Kenya have found a 4.2 million-year-old fossil of a miniature monkey which only weighed one kilogram. The newly discovered species, 'Nanopithecus browni', is the same size as the world's smallest Old World monkey, the talapoin. The dry grassland Kenyan habitat that 'Nanopithecus browni' lived in is also where some of earliest human ancestors' fossils have been discovered.