Ammonite stratigraphy of a Toarcian (Lower Jurassic) section on Nagy-Pisznice Hill (Gerecse Mts, Hungary)

Abstract In the Jurassic rocks exposed in a small abandoned quarry on the northwestern edge of Nagy-Pisznice Hill in the Gerecse Mts, fairly well preserved parts of a crocodile skeleton was found in 1996. The bed which yielded the skeletal remains is the uppermost layer of the Kisgerecse Marl Formation exposed here and was determined as belonging to the Upper Toarcian Grammoceras thouarsense Zone. The beds of the sequence above and below were carefully sampled in the late 1990s, and the encountered ammonites were evaluated biostratigraphically. As a result, the Lower Toarcian Harpoceras serpentinum Zone, the Middle Toarcian Hildoceras bifrons and Merlaites gradatus Zones, and the Upper Toarcian Grammoceras thouarsense and Geczyceras speciosum Zones were identified. Within most of these zones the subzones and even the faunal horizons were successfully recognized. The lowermost beds above the underlying Pliensbachian red limestone did not yield any fossils; thus the lowermost Toarcian Dactylioceras tenuicostatum Zone could not be documented. The highest Toarcian ammonite zones also remained unidentified, because the beds of the Tölgyhát Limestone above were not sampled all the way up. This paper presents the lithostratigraphic and biostratigraphic details of the sequence, and the paleontological descriptions of the most important ammonites

Tmetoceratidae (Ammonitina) fauna from the Gerecse Mts (Hungary)

Abstract Taxonomic and stratigraphic problems of the family Tmetoceratidae and the genera Dumortieria, Catulloceras, Cotteswoldia, Pleydellia and Tmetoceras included in it are briefly discussed. Fifteen species of Tmetoceratidae are described and illustrated from the Upper Toarcian-Aalenian ammonite assemblages of the Gerecse Mts (NE Transdanubian Range, Hungary). The fauna described here is closely allied to the Mediterranean Province of the Mediterranean-Caucasian Realm

New species and stratigraphic data on Lower Bajocian (Middle Jurassic) lytoceratids (Ammonoidea) from Lókút, Bakony Mts, Hungary

From exceptionally rich and mostly well-preserved Lower Bajocian ammonite assemblages, eight lytoceratid species are described and discussed in detail. They belong to four genera (Lytoceras, Megalytoceras, Alocolytoceras and Nannolytoceras) and include some stratigraphically important forms. Thus the material yielded the hitherto known youngest (Lower Bajocian Otoites sauzei Zone) representative of genus Alocolytoceras (A. isztimeri n. sp.). On the basis of here-identified forms,the range of Lytoceras subfrancisci could be extended up into the Otoites sauzei Zone. A new species (Nannolytoceras gibbosum n. sp.) from the Witchellia laeviuscula/Otoites sauzei zonal boundary interval suggests that the origin of Nannolytoceras could have been earlier than previously recorded. The faunal compositions of the assemblages reflect a typical Tethyan character, with lytoceratids representing only the third most numerous ammonite group behind Phylloceratina and Ammonitina