# Khok Kruat Formation

The Khok Kruat Formation (Thai: หมวดหินโคกกรวด) is a rock formation found in northeastern Thailand. It is the uppermost formation of the Khorat Group. 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. The group is a fluvial formation consisting primarily of red siltstones and sandstones.

## Vertebrate paleofauna

| 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. |
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. Fukuiraptor-like teeth have also been recovered from the formation.

### Reptiles
#### Dinosaurs

Dinosaurs reported from the Khok Kruat Formation :
| Genus | Species | Location | Material | Notes |
| cf. Asianopodus | cf. A. isp. | "Huai Dam Chum site, Ban Lao Nat, Tha Uthen District, Nakhon Phanom Province". | "At least 79 trackways composed of 341 consecutive tracks in total". | Theropod tracks. |
| Ichnogen. et. sp. indet. | | "Huai Dam Chum site, Ban Lao Nat, Tha Uthen District, Nakhon Phanom Province". | "Two trackways: T23 composed of 6 consecutive tracks and T35 composed of 3 discontinuous tracks". | Flattened possible theropod tracks. |
| Ornithomimosauria | Indeterminate | Ban Krok Duean Ha | "NRRU-F01020052, distal part of the right metatarsal III" | An ornithomimosaurian |
| Psittacosaurus | P. sattayaraki | Ban Dong Bang Noi | "Well preserved left dentary and an incomplete maxilla." | A ceratopsian |
| Ratchasimasaurus | R. suranareae | Nakhon Ratchasima province. | | An iguanodontian ornithopod |
| Siamodon | S. nimngami | Ban Saphan Hin | PRC-4, a well-preserved left maxilla, PRC-5, an isolated maxillary tooth and PRC-6, a braincase. | An iguanodontian ornithopod |
| Sirindhorna | S. khoratensis | Muaeng Nakhon Ratchasima District, Nakhon Ratchasima Province. | | An iguanodontian ornithopod |
| Siamosaurus | S. sp. | | Teeth | A spinosaurid |
| Siamraptor | S. suwati | Muaeng Nakhon Ratchasima District, Nakhon Ratchasima Province. | "A composite cranial and postcranial skeleton comprising premaxilla, maxilla, jugal, surangular, prearticular, articular, vertebrae, manual ungual, ischium, tibia, and pedal phalanx". | A carcharodontosaur |

#### Pseudosuchians

Pseudosuchians reported from the Khok Kruat Formation :
| Genus | Species | Location | Material | Notes | Images |
| Atoposauridae indet. | Indeterminate | Lam Pao Reservoir, Ban Noi, Sahatsakhan district, Kalasin province. | An isolated lanceolate tooth (PRCMR 282). | May be attributable to Theriosuchus. | |
| Khoratosuchus | K. jintasakuli | Ban Saphan Hin, Nakhon Ratchasima province. | A partial skull (NNRU-A 1803). | An advanced neosuchian. | |

#### Turtles

Turtles reported from the Khok Kruat Formation :
| Genus | Species | Location | Material | Notes | Images |
| Kizylkumemys | K. khoratensis | Ban Saphan Hin and Ban Khok Kruat localities, Nakhon Ratchasima province. | Shell material. | A carettochelyid. | |
| Shachemys | S. sp. | Ban Saphan Hin, Nakhon Ratchasima province. | Shell material. | An adocid, remains too fragmentary for specific assignment. | |

### Fish
#### Bony fish

Bony fish reported from the Khok Kruat Formation :
| Genus | Species | Location | Material | Notes | Images |
| Khoratamia | K. phattharajani | Ban Krok Duean Ha, Nakhon Ratchasima province. | Holotype (NRRU-F01020023), paratype (NRRU-F01020024) and a patch of scales (NRRU-F01020025). | An amiid. | |
| Lanxangichthys | L. sp. | Khok Pha Suam, Ubon Ratchathani province. | | A lepisosteiform. | |

#### Cartilaginous fish

Cartilaginous fish reported from the Khok Kruat Formation :
| Genus | Species | Location | Material | Notes |
| Acrorhizodus | A. khoratensis | Khok Pha Suam locality, Ubon Ratchathani province. | 5 teeth, most of them incomplete. | A hybodontiform. |
| Heteroptychodus | H. aff. steinmanni | Khok Pha Suam locality, Ubon Ratchathani province. | 20 teeth, most incomplete. | A ptychodontid. |
| Hybodus? | H.? sp. | Khok Pha Suam locality, Ubon Ratchathani province. | 22 incomplete teeth. | Possibly represents a new genus, but the available material is too fragmentary to warrant erecting a new taxon. |
| Thaiodus | T. ruchae | Khok Pha Suam locality, Ubon Ratchathani province. | One incomplete tooth. | A hybodontid. |