The locality of Khok Sung, Nakhon Ratchasima province, which corresponds to an ancient river terrace,
has yielded the richest Pleistocene fauna of Thailand with a thousand of fossil vertebrate remains. This
fauna has been previously dated between the Early Pleistocene and the Middle Pleistocene. We describe
here a nearly complete hyaenid skull and associated mandible identified as belonging to spotted hyaena
Crocuta crocuta ultima. The spotted hyaena C. c. ultima, which extended its maximum latitudinal distribution
from northern China to Peninsular Thailand, is a characteristic component of Southeast Asian
Middle Pleistocene faunas. These new biochronological data, coupled with a magnetostratigraphic study
of the lithological section, provide a powerful multiproxy approach for the dating of Khok Sung fauna,
pinpointing rather a late Middle Pleistocene age than the Early Pleistocene. In addition, the occurrence in
the Khok Sung section of a short reverse excursion of the magnetic field within the Brunhes normal
Chron can be tentatively identified as corresponding either to the “Iceland Basin” (188 ka) or to the
“Pringle Falls” (213 ka) excursion, suggesting an even more precise dating of the locality. According to the
presence of a spotted hyaena, the Khok Sung fauna may illustrate an open canopy habitat in a floodplain
with abundant and diversified herbivores, close to the main river channel. This interpretation contrasts
with the paleobotanical data which indicate wet and dry tropical forests and may instead describe the
surrounding upland vegetation.