# Jinju Formation

The Jinju Formation (Korean: 진주층; Hanja: 晋州層; RR: Jinju-cheung), also known as the Dongmyeong Formation (Korean: 동명층; Hanja: 東明層; RR: Dongmyeong-cheung) in some literature is an Early Cretaceous geologic formation in South Korea. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus. The depositional age of this formation spans from approximately 112.4 ± 1.3 to 106.5 million years ago (early Albian) based on detrital zircon U-Pb dating. It predominantly consists of black shale, with sandstone packets, deposited in a fluvial-lacustrine setting.
A diverse arthropod fauna, including freshwater arthropods, spiders, and insects, is known from the formation. Other notable fossils known from the formation include several freshwater fishes, ostracods, and plants. This formation has also "attracted global ichnological attention" for the variety of important ichnofossils. Columnar and rod-shaped stromatolites have also been found here.

## Fossil content
### Plants

Plants of the Jinju Formation :
| Genus | Species | Notes |
| Cupressinocladus | C. sp. | The presence of this conifer indicates that a mixed type of the Tetori-Type and the Ryoseki-Type flora existed in this formation. |
| Ruffordia | R. sp. | Schizaeaceae ferns |
| Cladophlebis | C. sp. | |
| Sphenopteris | S. sp. | |
| Onychiopsis | O. elongata | leptosporangiate ferns |
| Brachyphyllum | B. japonicum | |

### Spiders

Spiders of the Jinju Formation :
| Genus | Species | Region | Notes |
| Korearachne | K. jinju | Jinju | likely to be a lycosoid |
| Koreamegops | K. samsiki | Jinju | a lagonomegopid |
| Jinjumegops | J. dalingwateri | Jinju | a lagonomegopid |
| Mygalomorphae | indeterminate | Jinju | |
| Araneomorphae | indeterminate | Jinju | |
| Palpimanoidea | indeterminate | Jinju | |
| "Cribellate Entelegynae" | "species 1" "species 2" | Jinju | |

### Insects

Jinju formation consists of a diverse order of insects: Orthoptera, Homoptera, Mantodea, Diptera, Coleoptera, Hymenoptera, Dermaptera, Neuroptera, Blattoidea, Hemiptera, Odonata, Mecoptera, etc.

#### Odonata

Dragonflies and damselflies of the Jinju Formation :
| Genus | Species | Region | Member | Material | Notes | Image |
| Hemeroscopus | H. baissicus | | | | | |
| Koreapodagrion | K. coloratus | | | | | |

#### Dermaptera

Earwigs of the Jinju Formation :
| Genus | Species | Region | Member | Material | Notes | Image |
| cf. Pygidicranoidea | indeterminate | | | | | |

#### Orthoptera

Orthopterans of the Jinju Formation :
| Genus | Species | Region | Member | Material | Notes | Image |
| Panorpidium | P. spica | | | | A member of Elcanidae | |

#### Alienoptera

Alienopterans of the Jinju Formation :
| Genus | Species | Notes |
| Umenocoleus | U. minimus | A member of Umenocoleidae |
| Pseudoblattapterix | P. weoni | A member of Umenocoleidae |
| Petropterix | P. koreaensis | A member of Umenocoleidae |

#### Blattodea

Blattodeans of the Jinju Formation :
| Genus | Species | Region | Notes |
| Rhipidioblattina | R. sp. cf. R. radipinguis R?. sp. cf. R. jilinensis R. sp. A | | |
| Mesoblattina | M. sp. A M. sp. B M. sp. C M. sp. D | | |
| Samaroblatta | S. sp. cf. S. rhypha | | |
| Blattula | B. sp. cf. B. exetenuata B. sp. A | | |
| Mesoblattula | M. sp. | | |
| Sclerotermes | S. samsiki | Jinju | A termite known only from an isolated wing, uncertain placement |
| Indeterminate | A total of 13 indeterminate species | | |

#### Hemiptera

Hemipterans of the Jinju Formation :
| Genus | Species | Region | Member | Material | Notes | Image |
| Jinjupopovina | J. eosahwae | | | | A member of Yuripopovinidae | |

#### Hymenoptera

Hymenopterans of the Jinju Formation :
| Genus | Species | Notes |
| Korehelorus | K. jinjuensis | A parasitic wasp belonging to the family Heloridae |
| Hanguksyntexis | H. haeretica | A sawfly belonging to the family Anaxyelidae |
| Cretosphecium | C. jinjuensis | A wasp belonging to the family Angarosphecidae |

#### Raphidioptera

Snakeflies of the Jinju Formation :
| Genus | Species | Region | Member | Material | Notes | Image |
| Mesoraphidia | M. koreensis M. phantasma | | | | A member of Mesoraphidiidae | |

#### Neuroptera

Lacewings of the Jinju Formation :
| Genus | Species | Notes |
| Tachinymphes | T. koraiensis | A member of the family Mesochrysopidae. |
| Araripeneura | A. asiatica | A member of Araripeneuridae |
| Araripenymphes | A. koreicus | A member of Cratosmylidae |

#### Coleoptera

Beetles of the Jinju Formation :
| Genus | Species | Material | Notes |
| Coptoclava | C. sp. | Nymph remains abundant; Adult remains relatively rare | A member of the extinct family Coptoclavidae. Similar to C. longipoda, but assigned to a yet undescribed species since C. longipoda is usually considered to be a species complex. |
| Megalithomerus | M. magolhalmii | | A member of Elateridae |
| Koreagrypnus | K. jinju | | A member of Elateridae |
| Cretosaja | C. jinjuensis | | A member of Silphidae |
| Notocupes | N. premeris | | A member of Archostemata |
| Asiana | A. pax | | A member of Archostemata |
| Brochocoleus | B. sacheonensis | | A member of Ommatidae |
| Brochocoleus | B. cf. punctatus | | A member of Ommatidae |
| Omma | O. sp. | | A member of Ommatidae |
| Zygadenia | Z. cornigera | | A member of Ommatidae |
| Laetopsia | L. leei | | A member of Hydrophiloidea |
| Laetopsia | L. cf. hydraneoides | | A member of Hydrophiloidea |
| Laetopsia | L. sp. | | A member of Hydrophiloidea |
| Cretotaenia | C. pallida | | A member of Hydrophiloidea |
| Psacodromeus | P. recta | | A member of Trachypachidae |
| Necronectulus | N. lazarus | | A member of Trachypachidae |

#### Diptera

Flies of the Jinju Formation :
| Genus | Species | Region | Member | Material | Notes | Image |
| Buccinatormyia | B. gangnami | | | | A member of the family Zhangsolvidae. Named after Gangnam Style, the famous K-Pop hit song | |

### Crustaceans
#### Isopoda

Isopods of the Jinju Formation :
| Genus | Species | Region | Member | Material | Notes | Image |
| Archaeoniscus | A. coreaensis | | | | A freshwater occurrence of the genus Archaeoniscus | |

#### Ostracoda

Ostracods of the Jinju Formation :
| Genus | Species | Region | Notes |
| Scabriculocypris | S. yanbianensis | Jeongcheon | |
| Cypridea | C. jinjuria C. khandae C. samesi | C. jinjuria in Gwanghyeon | |
| Mongolocypris | M. kohi | | |
| Lycopterocypris | L. cf. celsa | Jeongcheon | |
| Candona | C. sp. | | |
| Djungarica | D. sp. | Jeongcheon | |
| Rhinocypris | R. sp. | | Previously assigned to as Ilyocypris sp. |

#### Spinicaudata

Clam shrimps of the Jinju Formation :
| Genus | Species | Region | Member | Material | Notes | Image |
| Yanjiestheria | Y. kyongsangensis Y. chekiangensis Y. cf. wannanensis Y. jinjuensis Y. sp. | | | | | |

### Vertebrates

Source:

#### Actinopterygii

Fishes of the Jinju Formation :
| Genus | Species | Region | Material | Notes |
| Wakinoichthys | W. aokii | | Multiple complete skeletons | An osteoglossiform |
| Jinjuichthys | J. cheongi | Jinju | Articulated skeletons | A possible ichthyodectiform, though this classification remains controversial |
| Albuliformes | indeterminate | | | |
| Sinamia | S. sp. | | Articulated incomplete tail | An amiiform |
| Lepidotes | L. sp. | | Articulated skeleton, missing the anterior part of the head | Largest fish found in this formation, reaching 40 cm (1.3 ft) in total length. |
| Elopiformes | indeterminate | | | A small fish, reaching 3 cm (1.2 in) in total length. |

#### Archosauria

Reptiles of the Jinju Formation :
| Genus | Region | Material | Notes |
| Crocodyliformes indet. | Goryeong | a right mandible | |
| Titanosauriformes indet. | Sacheon and Goryeong | teeth | A tooth from Sacheon was initially suggested to be of Asian Brachiosaurid by Lim, Martin and Baek (2001), but Barrett et al. (2002) and Choi & Lee (2017) consider it to be indeterminate titanosauriform. Meanwhile, another tooth from Goryeong was suggested to be of Diplodocoidea by Yun et al. (2007), but Choi and Lee (2017) also considered it indeterminate titanosauriform. |
| Pterodactyloidea indet. | Goryeong | teeth | While the KPE 40001 suggested to be of Boreopterid origin by Choi & Lee (2017), Yun (2021) and Yun (2024) consider them to be Anhanguerian instead based on the morphological disparity from Boreopteridae and the results of two-dimensional geometric morphometric analyses. |

### Mollusks
#### Bivalvia

Bivalves of the Jinju Formation :
| Genus | Species | Notes |
| Plicatounio | P. naktongensis | |
| Nagdongia | N. soni | The genus Nagdongia is considered to be synonymous with Nakamuranaia by some. |
| Trigonioides | T. jaehoi | |
| Sphaeriun | S. coreanicum | |

#### Gastropoda

Gastropods of the Jinju Formation :
| Genus | Species | Notes |
| Brotiopsis | B. kobayashi | Dominant gastropod of the formation |
| Thiara | T. sp. | |
| Viviparus | V. sp. | |

### Ichnofossils

Unnamed ichnofossils from the Jinju Formation include Ornithopod tracks and Caddisfly bioherms.
Ichnofossils of the Jinju Formation :
| Ichnogenus | Ichnospecies | Region | Notes |
| Gyeongsangsauropus | G. isp. | Jinju | Sauropod tracks |
| Grallator | G. isp. | Jinju | Theropod track; similar to the ichnospecies G. yangi |
| Corpulentapus | C. isp. | Jinju | Theropod track |
| Asianopodus | A. isp. | Jinju | Theropod track |
| Minisauripus | M. isp. | Jinju | One of the smallest known theropod tracks. Currently the oldest record of this ichnogenus from South Korea. |
| Dromaeosauriformipes | D. rarus | Jinju | The smallest known non-avian dinosaur didactyl tracks possibly made by a small microraptorine, with indication of important flight behaviors such as flap-running, take-off, and landing. |
| Dromaeosauripus | D. jinjuensis | Namhae | Didactyl tracks made by a 40 cm (1.3 ft) tall dromaeosaur. |
| Ignotornis | I. seoungjoseoi | Sacheon | Bird Track |
| Jindongornipes | J. isp. | Sacheon | Bird Track |
| Koreasaltipes | K. jinjuensis | Jinju | Traces left by a hopping mammal |
| Neosauroides | N. innovatus | Jinju | The largest reported lizard trackway in South Korea. |
| cf. Chelichnus | | Sacheon | Turtle trackway; first identified as Chelonipus isp. |
| Ranipes | indeterminate | Jinju | Oldest known frog trackway. Made by a species that hopped in short distances. |
| Crocodylopodus | C. isp. | Sacheon and Jinju | First report of this ichogenus from Asia. |
| Batrachopus | B. grandis | Sacheon | Archosaur track made by either a bipedal crocodylomorph or therizinosaur; the pterosaur trackway ichnospecies Haenamichnus gainensis from the Haman Formation is now assigned to this species as B. cf. grandis. Paleontologist James I. Kirkland expresses doubts on the ichnogenus assignment. |
| Pteraichnus | P. gracilis "P. seopoensis" | | Pterosaur trackway. P. seopoensis is currently a naked name, since it was only described in a master's thesis. |
| Lockeia | L. gigantus | | Resting trace, made by bivalve tracemakers |
| Diplichnites | D. isp. | | Arthropod tracks |
| Coclichnus | C. isp. | | Trace by Annelida tracemakers |
| Radialimbricatus | R. bitoensis | | Potential tracemakers include arthropods, cnidarians or annelids |
| Protovirgularia | P. dichotoma | | First nonmarine occurrence of this ichnotaxon; possibly made by larvae of dragonfly |
| Fictovichnus | indeterminate | | Probable insect cocoon or pupation chamber; the earliest record of an insect pupation structure probably associated with a burrow |
| Chondrites | C. isp. | | |
| Palaeophycus | P. tubularis | | |
| Helminthopsis | H. hieroglyphica | | |
| Skolithos | S. magnus | | |
| Taenidium | T. barretti | | |
| Torrowangea | T. rosei | | |