Khok Kruat Formation

The Khok Kruat Formation is a rock formation found in northeastern Thailand. It is the uppermost formation of the Khorat Group.[1] It is dated to the Aptian stage of the Early Cretaceous period, and is notable for its fossils of dinosaurs. It is equivalent to the Gres superieurs Formation of Laos.[2] The group is a fluvial formation consisting primarily of red siltstones and sandstones.[1]

Khok Kruat Formation Stratigraphic range: Aptian ~120–113 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Khorat Group
Underlies	Maha Sarakham Formation
Overlies	Phu Phan Formation
Lithology
Primary	Sandstone, siltstone
Other	Conglomerate, shale
Location
Coordinates	15.9°N 102.0°E
Approximate paleocoordinates	16.3°N 105.3°E
Region	Indochina
Country	Thailand
Extent	Khorat Plateau
Type section
Named by	Ward & Bunnag
Year defined	1964
Khok Kruat Formation (Thailand)

Vertebrate paleofauna

The Khok Kruat Formation has yielded remains of sharks, fishes, turtles, crocodilians and pterosaurs. Phuwiangosaurus-like teeth, Siamosaurus teeth, and fragmentary postcranial remains of spinosaurids have also been recovered from it.[3] Fukuiraptor-like teeth have also been recovered from the formation.[4]

Dinosaurs of the Khok Kruat Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Psittacosaurus	P. sattayaraki[5]	Ban Dong Bang Noi		"Well preserved left dentary and an incomplete maxilla."[3]	A ceratopsian
Ratchasimasaurus	R. suranareae[6]				An iguanodontian ornithopod
Siamodon	S. nimngami[7]	Ban Saphan Hin		PRC-4, a well-preserved left maxilla, PRC-5, an isolated maxillary tooth and PRC-6, a braincase.[7]	An iguanodontian ornithopod
Sirindhorna	S. khoratensis				An iguanodontian ornithopod
Siamosaurus	S. sp.[8]			Teeth	A spinosaurid
Siamraptor	S. suwati			A composite cranial and postcranial skeleton comprising premaxilla, maxilla, jugal, surangular, prearticular, articular, vertebrae, manual ungual, ischium, tibia, and pedal phalanx	A carcharodontosaur

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

See also

• List of dinosaur-bearing rock formations

References

1. Eric Buffetaut (2009). Late Palaeozoic and Mesozoic Ecosystems in SE Asia. Geological Society of London. p. 146. ISBN 978-1-86239-275-5.
2. Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, Asia)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 563-570. ISBN 0-520-24209-2.
3. Eric Buffetaut; Varavudh Suteethorn; Jean Le Loeuff; Sasidhorn Khansubha; Haiyan Tong; Kamonlak Wongko (2005). "New dinosaur species from the Upper Triassic Upper Maleri and Lower Dharmaram formations of central India". International Conference on Geology, Geotechnology and Mineral Resources of Indochina (GEOINDO 2005): 575–581.
4. Chokchaloemwong, Duangsuda; Azuma, Yoichi; Shibata, Masateru; Jintasakul, Pratueng (2015). "The Carcharodontosaurid Teeth from the Lower Cretaceous Khok Kruat Formation of Nakhon Ratchasima, Thailand". 2nd International Symposium on Asian Dinosaurs 2015 Bangkok.
5. Buffetaut, Eric & Suteethorn, Varavudh. (1992). A new species of the ornithischian dinosaur Psittacosaurus from the Early Cretaceous of Thailand. Palaeontology 35: 801-812.
6. Masateru Shibata, Pratueng Jintasakul, and Yoichi Azuma (2011). "A New Iguanodontian Dinosaur from the Lower Cretaceous Khok Kruat Formation, Nakhon Ratchasima in Northeastern Thailand". Acta Geologica Sinica - English Edition. 85 (5): 969–976. doi:10.1111/j.1755-6724.2011.00230.x.CS1 maint: uses authors parameter (link)
7. Eric Buffetaut and Varavudh Suteethorn (2011). "A new iguanodontian dinosaur from the Khok Kruat Formation (Early Cretaceous, Aptian) of northeastern Thailand". Annales de Paléontologie. 97 (1–2): 51–62. doi:10.1016/j.annpal.2011.08.001.CS1 maint: uses authors parameter (link)
8. Milner, Angela; Buffetaut, Eric; Suteethorn, Varavudh (2007). "A tall-spined spinosaurid theropod from Thailand and the biogeography of spinosaurs". Journal of Vertebrate Paleontology. 27 (supplement 3): 118A.