Abstract: Belemnites from Late Valanginian to earliest Barremian sedimentary rocks of the Bersek-hegy (Gerecse Mts, Hungary) are described and compared to faunas from other regions. Early Barremian to "Mid" Barremian faunas are briefly mentioned and will be published in more details in part II. Since the sampled sections also yielded rich ammonite assemblages, the belemnite stratigraphy can be evaluated within the well-studied Mediterranean ammonite zones. The Upper Valanginian to Barremian Hibolithes are discussed, i.e. "Subfusiformi" of Shvetsov, 1913. The status of Mesohibolites Stolley, 1919 is briefly discussed but will be described in detail in part II, as more research is needed to unravel the "Mesohibolites". A new genus will be introduced for the Upper Valanginian to lowermost Hauterivian part of Mesohibolites s. l. [= pars Combemorelites Gayte, 1984 (MS)], i.e. Adiakritobelus n. gen. The Early, "Mid" and Late Hauterivian are characterised by Hibolithes (gr.) subfusiformis, Duvalia dilatata spp., Pseudoduvalia spp. and Pseudobelus brevis. Uppermost Hauterivian to lowermost Barremian belemnite genera and species are comparable to the Duvaliidae-Hibolithes association, characteristic for this stratigraphical interval in southeast France. "Mesohibolites" spp. and Duvalia grasiana (Duval-Jouve, 1841) characterize the late Lower Barremian, while the "Mid" Barremian (latest Lower Barremian and earliest Upper Barremian) is characterised by Curtohibolites spp. Faunal differences in various areas in the Tethys are believed to be the result of incompleteness of the published faunas and do generally not have a palaeobiogeographical background. Lectotypes are indicated for Belemnites josephinae (Honnorat-Bastide, 1889) and Hibolites jaculiformis Shvetsov, 1913.Keywords:
Author(s): Janssen, N. M. & Főzy, I.
Title: Neocomian belemnites from the Bersek-hegy (Gerecse Mountains, Hungary) part I: Late Valanginian to earliest Barremian
stratigraphy, Valanginian, Hauterivian, Barremian, belemnite, ammoniteJournal: Fragmenta Palaeontologica HungaricaJournal abbreviation: Fragm. Palaeont. Hung.ISSN: 1586-930XPublisher: Hungarian Natural History Museum, BudapestEditor(s): Szabó, J.
& Matskási, I.