September 2023: Publication Tropical Natural History
Asian Miocene Great Apes: Searching for Orangutan Ancestors
Pongids are represented today by the genus Pongo (orangutan), with three species that live on islands of Southeast Asia. However, orangutans were much more widely distributed during the Pleistocene. The changes in their geographical distribution and taxonomy are discussed here since the first appearance of this genus in the early Pleistocene (⁓2.2 million years ago) in South China. During the Pleistocene, orangutans coexisted with Gigantopithecus in South China, sharing their food and environment. Between the middle and late Miocene (12.5–5.4 million years ago), four distinct large apes were evolving in South and Southeast Asia. Each genus has been proposed as a potential ancestor of extant orangutans. However, Lufengpithecus, from South China is excluded from the pongids and is interpreted as having Eurasian dryopithecines ancestors. Sivapithecus, from India-Pakistan, exhibits orangutan skull characters but its dentition is more primitive, and its postcranial skeleton is specialized in another locomotory repertoire. Indopithecus appears to be the closest relative of Sivapithecus and is considered a potential ancestor of Gigantopithecus. Khoratpithecus, from Thailand and Myanmar, is recognized as the closest sister taxon of extant orangutans because both genera share characters such as the symphysis structure, teeth and jaw morphology, the absence of anterior digastric muscles of the mandible, and the organization of the nasoalveolar clivus. However, the absence of Pliocene large apes in Southeast Asia prevents us from documenting the evolutionary transition between Khoratpithecus and orangutans.
FIGURE 4. Comparison of skulls and face structures of A) Pongo, B) Sivapithecus indicus (GSP 15000), and C) Lufengpithecus lufengensis (PA644) from Xu and Lu (2008) in frontal view. Not to scale.
References
Chaimanee Y., Jaeger J.-J. 2023 – Asian miocene great apes: searching for orangutan ancestors – Tropical Natural History Supplement 7, 260–275 – Détails de l’article…