Kruat Formations had a more semi-arid climate than the older, more humid Phu Kradung Formation, dated to the Berriasian. The Khok Kruat Formation is composed mostly of sandstones, conglomerates, siltstones, and shales. Similar to the Sao Khua Formation, the deposition of these sediments occurred in an arid to semi-arid floodplain environment of slow-moving, meandering rivers. This ecosystem included pterosaurs, sinamiid fish; carettochelyid and acocid turtles; ptychodontid, hybodontid, and thaiodontid sharks; and the crocodyliform Khoratosuchus jintasakuli, as well as goniopholidids. Besides Siamosaurus, the dinosaur fauna of the Khok Kruat Formation included the carcharodontosaurid Siamraptor suwati; iguanodontians like Sirindhorna khoratensis, Ratchasimasaurus suranaerae, and Siamodon nimngami; a titanosauriform sauropod similar to Phuwiangosaurus; an indeterminate ceratopsian; and various indeterminate theropods. The formation is probably equivalent to the Grès supérieurs Formation of Laos, since animals like spinosaurids, sauropods, and derived ("advanced") iguanodontians have also been found there. In 2007, Milner and colleagues suggested that spinosaurids and iguanodontians may have spread from western to eastern Laurasia—the northern supercontinent at the time—during the Aptian, based on their distribution and presence in the Khok Kruat Formation. American palaeontologist Stephen Brusatte and colleagues noted in 2010 that the discovery of spinosaurids in Asia, a family previously known only from Europe, Africa, and South America, suggests a faunal interchange between Laurasia and Gondwana (in the south) during the early Late Cretaceous. Though it may also be possible that spinosaurids already had a cosmopolitan distribution before the Middle Cretaceous, preceding the breakup of Laurasia from Gondwana. However, the authors noted that more evidence is needed to test this hypothesis. In 2012, Allain and colleagues suggested such a global distribution may have occurred earlier across Pangaea before the Late Jurassic, even if Asia became separated from the supercontinent first. In 2019, Spanish palaeontologist Elisabete Malafaia and colleagues also indicated a complex biogeographical pattern for spinosaurs during the Early Cretaceous, based on anatomical similarities between Ichthyovenator and the European genus Vallibonavenatrix. References External links Spinosaurids Barremian life Early Cretaceous dinosaurs of Asia Cretaceous Thailand Fossils of Thailand Fossil taxa described in 1986 Taxa named by Éric Buffetaut