size range suggests the teeth are from individuals of different ages. Among theropods, this may also indicate size variation along the tooth row in the jaws, which is observed to have been prevalent in spinosaurids. The holotype tooth is relatively straight, with only minor front to back curvature. It is oval in cross-section while other specimens are nearly circular in this aspect. Unlike in most theropods, the carinae (cutting edges) of Siamosaurus teeth lack well-defined serrations, though unworn teeth do exhibit very fine denticles. Some teeth (including the holotype) have a wave-like double recurvature when viewed from the front or back, which Buffetaut and Ingavat compared to that seen in carnosaur teeth from the same formation and one Deinonychus tooth described by John Ostrom in 1969. The S. suteethorni holotype is symmetrically concave front to back, and bears 15 flutes (lengthwise grooves) on its lingual (inward facing) and labial (outward facing) surfaces. These flutes run from the base of the crown before stopping from the rounded tooth tip. A region of the holotype where the enamel (outer layer of the teeth) has weathered away reveals that these flutes extend down to the dentin (second layer of the teeth). The enamel also has a granular (finely wrinkled) texture, as seen in teeth from the spinosaurid Baryonyx. Some of the root is preserved in the holotype and, as in all theropods, there is a large pocket for the tooth pulp, which would have housed blood vessels and nerves. Khok Kruat teeth Of the two Khok Kruat Formation tooth morphotypes assigned by Kamonrak and colleagues in 2019, morphotype I, the Khok Kruat morphotype, is on average in total length, of which the crown takes up , with a wide base. They are oval in cross-section, have well-defined carinae, and a smooth enamel surface, which becomes wrinkled at the base of the crown. They bear fine, sharply defined flutes, of which there are about 21 to 32 on each side. Morphotype II, the Siamosaurus morphotype, is on average long, with a tall crown that is wide at the base. They are also oval in cross-section and have distinct carinae, but unlike the Khok Kruat morphotype, the entire length of the crown has wrinkled enamel, and the flutes are coarser and fewer in number, with 11 to 16 on each side. The Siamosaurus morphotype also shares with S. suteethorni, GMNH-PV-999, and IVPP V 4793 a