Theropithecus

Theropithecus is a genus of Old World monkeys in the family Cercopithecidae, tribe Papionini. It includes the living gelada (Theropithecus gelada) and several extinct species known from fossil records, such as Theropithecus oswaldi. The genus is closely related to baboons and other papionins, and it forms a distinct branch within the diversification of Africa’s cercopithecoids.

Distribution and habitat: The only living species, the gelada, is endemic to the Ethiopian Highlands, where it inhabits high-altitude grasslands and cliff-edge habitats. Fossil Theropithecus species had a wider African distribution in the fossil record, indicating a once more widespread lineage.

Physical characteristics: Geladas are large-bodied primates with long limbs and thick fur. Males are generally larger than females and display pronounced secondary sexual characteristics, including a bare, usually bright red patch of skin on the chest that swells during the breeding season. The dental formula is 2.1.2.3, like other cercopithecines. The pelage is gray-brown, with a characteristic mane in males.

Behavior and ecology: Geladas are highly social and live in multi-level societies comprising one-male units within larger bands. They are primarily herbivorous, feeding almost exclusively on grasses, and have specialized dentition and gut adaptations for grazing. They exhibit complex vocalizations and grooming behaviors, with female bonds and male competition shaping social dynamics. Reproduction is seasonal, with about a six-month gestation.

Evolution and conservation: Theropithecus belongs to the Papionini lineage of cercopithecoids and is most closely related to baboons. The gelada is currently listed as Vulnerable on the IUCN Red List, with habitat loss and human activity as ongoing threats; fossil species document the genus’ broader historical range.