A distinctive new theropod dinosaur track from the Cretaceous of Thailand: Implications for theropod track diversity

Highly distinctive, well-preserved, three-toed dinosaur footprints with bilobed heel impressions from the Cretaceous of Thailand are assigned to the new ichnotaxon Siamopodus khaoyaiensis. The tracks, which represent small- to medium-sized gracile theropods, are unlike any previously known from Thailand or elsewhere. By contrast other robust, small- to medium-sized theropod tracks with bulbous heel impressions are reported from a new locality and shown to be similar to Lower Cretaceous tracks from elsewhere in Asia. When added to previously reported robust, large theropod tracks, the Cretaceous track record in Thailand appears dominated by a significant diversity of theropod track types that differ from one locality to the next. Thus, the track record is in general agreement with the skeletal record of theropods in Thailand. The occurrence of footprints with bilobed heel impressions is reviewed briefly.