Maxilla of Siamopithecus eocaenus (Anthropoidea, Primates) from the Paleogene of Krabi, Thailand, and its taxonomic status.

Detailed descriptions of the maxillae of Siamopithecus eocaenus, discovered from the latest Eocene/earliest Oligocene lignite mine in the Krabi basin of Peninsular Thailand, are presented. They include the morphology of P-M, the palate, a partial orbital region, and the zygomatic root. The specimen exhibits distinctive dental features including a single-rooted P alveolus, a protocone on the P and P, and a true hypocone on the upper molars, indicating its derived anthropoid dentition.