a bare black face and chest, small ears, bare shaped brows that are joined, and nostril margins that are raised. They are clearly not the largest gorillas and the distinctiveness of their external characters still needs to be verified. Other statistics include: Average adult male height: . Average adult male weight: . Average adult female height: . Average adult female weight: . Evolution In 2000 Esteban E. Sarmiento and John F. Oates proposed and supported the hypothesis that the Cross River gorilla began to evolve into a distinct subspecies of Gorilla gorilla during an arid period of the African Pleistocene phase in response to declining food sources and a greater emphasis on herbivory and terrestrial behaviors. The team stated that ancestors to the Cross River gorilla may have been secluded to the forests near the Cross River headwaters and/or elsewhere in the Cameroon highlands. They wrote that the Cross River gorillas may not have spread much since their isolation. The Gorilla gorilla gorilla ancestors differentiated from the Cross River gorilla by spreading beyond this area somewhere to the south and/or east of the Sanaga. Sarmiento and Oates stated that there is no evidence to suggest that G. g. gorilla and G. g. diehli are sympatric. Habitat The Cross River gorilla, like many other gorilla subspecies, prefer a dense forest habitat that is uninhabited by humans. Due to the Cross River gorilla’s body size they require large and diverse areas of the forest to meet their habitat requirements. Similar to most endangered primates, their natural habitat exists where humans are often occupying and using for natural resources. Forests that are inhabited by the Cross River gorilla vary in altitude from approximately above sea level. Between 1996 and 1999, Field work was conducted on Afi Mountain in Cross River State, Nigeria for a period of 32 months. A great deal of data were collected, and things such as habitat types and topography mapped using line transects, climate, spatial and temporal availability of tree and herb foods and also the Cross River gorilla's wide range behavior, diet, and its grouping patterns. These data were all assessed from indirect evidence, such as feeding trails, nests, and feces. The habitats of the Cross River gorilla are negatively affected by the drastic deforestation and fragmentation of the land. These unfortunate events leave the gorilla species with few options for survival. As a result of deforestation and