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 and 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 Location Stratigraphic position Abundance Notes Images 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, dinosaursWeishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 588-593. . and pterosaurs present in Veszprém, Hungary, near the village of Németbánya in the Iharkút locality, an open-pit bauxite mine.Makádi, L., Botfalvai, G., Ősi, A. 2006: Egy késő-kréta kontinentális gerinces fauna a Bakonyból: halak, kétéltűek, teknősök, gyíkok. Földtani Közlöny 136/4, pp. 487-502. Other finds include Abelisauridae indet., Rhabdodontidae indet.,Ősi, A. & Rabi, M., 2006. Egy késő-kréta kontinentális gerinces fauna a Bakonyból II.: krokodilok, dinoszauruszok, pteroszauruszok és madarak (The Late Cretaceous continental vertebrate fauna from the Bakony Mountains II: crocodiles, dinosaurs (Theropoda, Aves, Ornithischia), pterosaurs). Földtani Közlöny, 136, 4, 503–526. Tetanurae indet. Coprolites and eggshells are also known from the locality.
Fish Fish Genus Species Location Stratigraphic position Abundance Notes Images Atractosteus Indeterminate Iharkút locality "Jaw fragments, teeth, scales, vertebrae" Gar, genus extant Coelodus Indeterminate Possible dentary/premaxilla, vomers, prearticulars, teeth and possible scales Pycnodontiform Polazzodus P. mihalyfii A pycnodontid pycnodont 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 Stratigraphic position Abundance Notes Images 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 Location Stratigraphic position Abundance Notes Images 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 Location Stratigraphic position Abundance Notes Images 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 Location Stratigraphic position Abundance Notes Images 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 Stratigraphic position Abundance Notes Images Bakonydraco B. galaczi Veszprém "Premaxilla, complete mandible, 56 mandibular symphyses" Tapejarid Azhdarchidae Indeterminate "Cervical vertebrae, pelvic girdle elements, limb bones" Pterodactyloidea Indeterminate "3 mandibular symphyses"
Dinosaurs Dinosaurs of the Csehbánya Formation Genus Species Location Stratigraphic position Abundance Notes Images Ajkaceratops A. kozmai Fused premaxillae and rostral bones, with fragments of the maxillae, four predentaries. Referred teeth. A ceratopsian Bauxitornis B. mindszentyae Single right tarsometatarsus Avisaurid enantiornithine Hungarosaurus H. tormai Veszprém Several partial skeletons Struthiosaurine nodosaur 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
See also List of dinosaur-bearing rock formations List of fossiliferous stratigraphic units in Hungary
References