Abnormal fossil upper molar of Pongo from Thailand: Quaternary climatic changes in southeast Asia as a possible cause

We interpret an unusual left M-3 attributed to Pongo from the Late Middle P leistocene of Thailand to be an abnormal tooth rather than a supernumeracy molar. Its peculiar morphology cannot be related to classical known causes that affect the dental germ: Gemination, schizodontia, synodontia. The onto genic mechanism that might have led to the morphology of the tooth perhaps reflects stress related to a phase of marked climatic changes during the La te Middle Pleistocene in Southeast Asia.