Spinosaurid theropod teeth from the Red Beds of the Khok Kruat Formation (Early Cretaceous) in Northeastern Thailand

Abstract

Teeth from the Aptian - Albian Khok Kruat Formation of the Khorat Group in Northeastern Thailand, are described as belonging to spinosaurine dinosaurs. They consist of two morphotypes, i.e., the Khok Kruat morphotype and Siamosaurus morphotype. The Khok Kruat morphotype shows fine ridges and a smooth enamel surface of the crown while the Siamosaurus morphotype shows coarse ridges and a wrinkled enamel surface. Comparisons of the Thai material with the teeth of Asian and other spinosaurids indicate that the Khok Kruat morphotype is similar to other Asian spinosaurid teeth and more closely to those of Siamosaurus suteethorni or Siamosaurus morphotype from the older Sao Khua Formation of Northeastern Thailand. The differences in their morphology indicate a greater diversity of spinosaurids in Thailand and Asia.