# Csehbánya Formation

The Csehbánya Formation is a geological formation in the Transdanubian Mountains of Veszprém County, Hungary. The formation dates to the Late Santonian (around 85-84 million years ago) of the Late Cretaceous. It represents a floodplain environment as opposed to the swampy lacustrine environment of the simultaneous Ajka Coal Formation, though there is complete overlap in terms of fauna. It underlies the Jákó Marl Formation, and laterally transitions to the Ajka Coal Formation.

## Geology

The lithology of the unit is a cyclic variation of conglomerate, sandstone, variegated siltstone, clay and marl layers with some sporadic thin coal seams. It is unconformably overlies the Late Triassic Main Dolomite Formation, which has deposits of the Upper Cretaceous Nagytárkány Bauxite Formation within deep karstic sinkholes in the formation. There is a basal conglomerate of dolomite clasts at the base of the Csehbánya formation. The main exposed portion of the formation is called the Iharkút locality, which is a disused bauxite quarry. At this location due to Paleogene uplift, it is unconformably overlain by the Lutetian Ikharkút Conglomerate. In the upper levels of the formation, there are sandstone lens beds present, which represent channel bodies. These are indicative of an anastomosing fluvial system. The exposure at this locality is between 100–150 m. Most of the fossils are found within the SZ-6 site at the locality, which is interpreted as a lag channel deposit

## Invertebrate paleofauna

Amber is known from both the Ajka Coal and Csehbánya Formations, and is commonly referred to as ajkait. However most of the arthropod inclusions in these are undescribed, only being shown in photographs, with only two species of Ceratopogonids (biting midges) in the extant genus Leptoconops and the extinct genus Adelohelea being described. A list of known taxa is given below.
Invertebrates :
| Genus | Species | Notes |
| Adelohelea | A. magyarica | Biting midge |
| Leptoconops | L. clava | Biting midge, genus currently extant |
| Coleoptera | Indeterminate | |
| Diptera | Indeterminate | |
| Hymenoptera | Indeterminate | |
| Nematocera | Indeterminate | |

## Vertebrate paleofauna

Fishes, amphibians, turtles, squamates, crocodilians, dinosaurs and pterosaurs present in Veszprém, Hungary, near the village of Németbánya in the Iharkút locality, an open-pit bauxite mine. Other finds include Abelisauridae indet., Rhabdodontidae indet., Tetanurae indet. Coprolites and eggshells are also known from the locality.

### Fish

Fish :
| Genus | Species | Location | Abundance | Notes |
| Atractosteus | Indeterminate | Iharkút locality | "Jaw fragments, teeth, scales, vertebrae" | Gar, genus extant |
| Coelodus | Indeterminate | | Possible dentary/premaxilla, vomers, prearticulars, teeth and possible scales | Pycnodontiform |
| Vidalamiinae | Indeterminate | | "Two vertebrae" | |
| Amiidae | Indeterminate | | A left anterior ceratohyal and a vertebra | |
| Elopiformes | Indeterminate | | 13 vertebrae | |
| Ellimmichthyiformes | Indeterminate | | At least two distinct taxa represented by four and one vertebrae | Clupeimorph |
| cf. Salmoniformes | Indeterminate | | two vertebrae | |
| Acanthomorpha | Indeterminate | | Three vertebrae and 18 fin spines | |
| Teleostei | Indeterminate | | Teeth, vertebrae and cycloid scales | |
| Actinopterygii | Indeterminate | | 9 distinct teeth morphotypes and some teeth bearing elements | |

### Amphibians

Amphibians :
| Genus | Species | Location | Abundance | Notes |
| Albanerpeton | Indeterminate | Iharkút locality | Skull and jaw elements | Albanerpetontid |
| Bakonybatrachus | B. fedori | Iharkút locality | Pelvic elements | Discoglossid frog |
| Hungarobatrachus | H. szukacsi | Iharkút locality | Pelvic elements | Advanced frog |
| Palaeobatrachidae | Indeterminate | Iharkút locality | Postcranial remains | |
| Pelobatidae | Indeterminate | Iharkút locality | Postcranial remains | |

### Squamates

Squamates :
| Genus | Species | Abundance | Notes |
| Bicuspidon | B. aff. hatzegiensis | Fragmentary mandibles, maxillae | Polyglyphanodontid |
| Chromatogenys | C. tiliquoides | Partial right mandible | Scincomorph |
| Distortodon | D. rhomboideus | Dentaries, maxilla | Polyglyphanodontid |
| Pannoniasaurus | P. inexpectatus | Partial skeleton | Mosasaur, also known from Ajka Coal Formation |
| Pelsochamops | P. infrequens | Fragmentary dentary, dentary fragments | Chamopsiid |
| Scincomorpha | Indeterminate | Fragmentary dentaries | At least 3 distinct taxa, 4 mentioned in paper, but unsure if this counts Chromatogenys |

### Crocodyliformes

Crocodyliformes of the Csehbánya Formation :
| Genus | Species | Abundance | Notes |
| Iharkutosuchus | I. makadii | "Complete and partial skulls, mandibles, various cranial elements, teeth" | Hylaeochampsid |
| Doratodon | D. carcharidens | "Teeth, Jaw fragment" | |
| ?Theriosuchus | Indeterminate | "Teeth, cranial elements" | |
| ?Allodaposuchus | Indeterminate | "Teeth, jaw fragments, cranial elements" | |

### Turtles

Turtles of the Csehbánya Formation :
| Genus | Species | Abundance |
| Foxemys | F. trabanti | "Complete and partial skulls, mandibles, vertebrae, pectoral and pelvic girdle elements, limb bones, plastron and carapax fragments" |
| Kallokibotion | Indeterminate | Shell fragments |
| Dortokidae | Indeterminate | Shell fragments |

### Pterosaurs

Pterosaurs of the Csehbánya Formation :
| Genus | Species | Location | Abundance | Notes |
| Bakonydraco | B. galaczi | Veszprém | "Premaxilla, complete mandible, 56 mandibular symphyses" | Tapejarid |
| Azdarchidae | Indeterminate | | "Cervical vertebrae, pelvic girdle elements, limb bones" | |
| Pterodactyloidea | Indeterminate | | "3 mandibular symphyses" | |

### Dinosaurs

Dinosaurs of the Csehbánya Formation :
| Genus | Species | Location | Abundance | Notes |
| Ajkaceratops | A. kozmai | | Fused premaxillae and rostral bones, with fragments of the maxillae, four predentaries. Referred teeth. | Ornithischian, possibly a ceratopsian |
| Bauxitornis | B. mindszentyae | | Single right tarsometatarsus | Avisaurid enantiornithine |
| Hungarosaurus | H. tormai | Veszprém | Several partial skeletons | Struthiosaurine nodosaur |
| Mochlodon | M. vorosi | | Partial skull and postcrania | Rhabdodontid |
| Pneumatoraptor | P. fodori | Veszprém | Single left scapulocoracoid | Paravian |
| Struthiosaurus | Indeterminate | | Humerus and partial hip, and pelvic armor elements. | Struthiosaurine nodosaur |
| Abelisauridae | Indeterminate | | Femur and pedal ungual phalanx | |
| Enantiornithes | Indeterminate | | Limb bones | |
| Paraves | Indeterminate | | "Teeth, caudals, limb bones" | |
| Sauropoda | Indeterminate | | Single tooth | |
| Tetanurae | Indeterminate | | More than 50 teeth | |