it as a possible spinosaurine, given its lack of dental serrations. Likewise in 2010, British palaeontologist David Hone and colleagues placed Siamosaurus and "S." fusuiensis in the Spinosaurinae. British palaeontologist Thomas Arden and colleagues identified Siamosaurus as a basal (early diverging or "primitive") member of this subfamily in 2019; their cladogram can be seen below: Later in 2019, the Khok Kruat Formation teeth were also referred to the Spinosaurinae by Kamonrak and colleagues, on the basis that both the Khok Kruat and Siamosaurus morphotypes lack characteristics seen in baryonychines, such as long and slender roots, 0–10 flutes on each side, no well defined carinae, a sculptured surface of the crown base, and 45 degree orientation of the blood grooves. But they share with spinosaurines a sub-circular to oval cross-section, fluted tooth crowns, well defined front and rear carinae, distinct striations on the crown, varying denticle size, and a wrinkled surface of the crown base. The authors also noted that unlike spinosaurines such as Irritator and Spinosaurus, Asian spinosaurines usually have more laterally compressed tooth crowns, and wrinkles across more of the enamel surface. In 2020, a paper by British palaeontologist Robert Smyth and colleagues considered S. suteethorni a dubious name and attributed its teeth to an indeterminate spinosaurine, given the uncertainties of classifying spinosaurid teeth at the genus or species level, as well as the degree of heterodonty (variation within the tooth row) that spinosaurines apparently exhibited. Due to new discoveries and research on spinosaurid teeth since Siamosaurus was named in 1986, a reassessment of the genus' validity is currently being prepared by Buffetaut. Palaeobiology Diet and feeding Buffetaut and Ingavat suggested in 1986 that Siamosaurus probably led a heavily piscivorous (fish-eating) lifestyle, since its dentition—like those of other spinosaurids—had a highly specialised morphology better suited for piercing rather than tearing flesh, due to the long, straight conical tooth crowns with reduced or absent serrations. The authors noted that this dental morphology is also seen in other piscivorous predators like plesiosaurs and long-snouted crocodilians. Such a dietary preference had been suggested for Baryonyx the same year by British palaeontologists Angela Milner and Alan Charig, and was later confirmed in 1997 with the discovery of acid-etched fish scales inside the body cavity of its holotype skeleton. The elongate, interlocking jaws of spinosaurids also had snout tips that fanned out into a rosette-like shape—a trait also observed in highly piscivorous crocodilians such