Aalenian and Bajocian ammonites from the Qiangtang block (North Tibet) are described. Comparisons with successions of similar age in Europe allow the establishment of a correlation at zonal level. The relationship between early stephanoceratids and the otoitid Emileites is discussed. Emileites callomoni sp. nov. is erected. Haplopleuroceras , Fontannesia , Witchellia and Sonninia also occur and their significance highlighted. A lectotype for Haplopleuroceras mundum Buckman is designated.

Aalenian to Lower Bajocian ammonites from the Qiangtang block (North Tibet)

A revision of the Bajocian Lissoceratinae is presented. The study of a huge quantity of lissoceratins from different sites of the Western Tethys (Northwest European, Sub-Mediterranean and Mediterranean bioprovinces) within the Tethys-Panthalassa Realm provided data useful to implement the systematics of these almost neglected, never deeply analysed ammonites. Two genera, Lissoceras Bayle and Semilissoceras n. gen., are described with 16 species, among which 8 (four dimorphic, three macroconchiate and one microconchiate) new species: L. submediterraneum, L. maizetense, L. ovale, L. sturanii, L. maerteni, S. ellipticum, S. turgidulum and S. costellatum. The neotype of L. oolithicum is established. The microconchiate genus Microlissoceras is regarded as the junior synonym of the macroconchiate Lissoceras. Taxa are discussed according to four groups that gather taxa sharing common morpho-structural features. They roughly relate to successive biochronostratigraphical intervals within the Bajocian Stage and are headed by species largely known in literature: S. semicostulatum (Buckman) with suboval to compressed whorl section and rectiradiate ribs on the outer half flank; L. oolithicum (d’Orbigny) with subtriangular to ovate whorl section, large and depressed ventral saddle, large suspensive lobe; L. haugi Sturani with ovate to globular whorl section, narrow lobe E and suspensive lobe; and L. psilodiscus (Schloenbach) with highly compressed whorl section, high ventral saddle and narrow lobe E. The phyletic relation of Lissoceras and Semilissoceras to the Aalenian-Bajocian Bradfordia-group is discussed, regarding Semilissoceras as the known stem-taxon on which the subfamily Lissoceratinae bases.

Bajocian lissoceratinae (haploceratoidea, ammonitida) from the mediterranean-caucasian subrealm

\n This paper provides the first assessment of the paleoecology and biogeography of foraminiferal assemblages from the continuous Aalenian–lower Bajocian succession from the pelagic region of the Neotethys. Foraminiferal assemblages were extracted by glacial acetic acid from the Tűzkövesárok section B of Bakonycsernye (Hungary), which is well dated by ammonites and consists of Ammonitico Rosso type limestones. Palaeoenvironmental changes were evaluated based on microfacies studies, taxonomic and palaeoecological analyses (abundance, diversity, morphogroups, and ecozones) of the 49 benthic and one planktic taxa. The grazer-dominated foraminiferal assemblages indicated normal marine salinity and well-oxygenated conditions in a pelagic swell-graben environment below the photic zone. The majority of the foraminifera likely grazed on a biofilm or mat produced by microbes and/or fungi and also may have fed on marine snow. At the Aalenian–Bajocian transition, the decrease in abundance and diversity was linked with a sea-level fall event (JBj1). In the upper Bajocian, dissolution due to deepening resulted in the gradual and selective impoverishment of the fauna. In addition, two biomes, Boreal-Atlantic and Mediterranean, were distinguished within the area of the Boreal-Atlantic-Caucasian Province, based on the review of the coeval faunas.

Aalenian–Lower Bajocian Foraminiferal Fauna from the Ammonitico Rosso Series of Bakonycsernye (Hungary). Part 2: Palaeoecological and Palaeobiogeographical Aspects

Biostratigraphy is presented for horizons in the Discites to Sauzei zones at Coombe Quarry and Top Field at Mapperton, Dorset. The significance of these horizons is highlighted. Part of a chronocline is described in the Sonniniidae of the Discites Zone. A new ammonite faunal horizon, Docidoceras higginsi sp. nov. is erected as the oldest of the Ovale Zone. A revised subdivision of the zone is presented and the implications for the taxonomy and biogeography of the Stephanoceratidae is discussed. The distribution of Docidoceras may imply entry to western Tethys via a Hispanic Corridor. A method is presented for the allocation of generic names constituting segments of lineages.

A new ammonite faunal horizon in the Ovale Zone (Middle Jurassic, Lower Bajocian) and observations on the ammonite genus Sonninia at Coombe Quarry, Mapperton, near Beaminster, Dorset

\n This paper provides the first record of isolated foraminiferal assemblages from the continuous Aalenian–lower Bajocian succession from the pelagic region of the Neotethys. The studied Tűzkövesárok section B of Bakonycsernye (Hungary) has been well dated by ammonites and consists of Ammonitico Rosso type limestones. The foraminiferal fauna extracted by glacial acetic acid yielded 49 benthic taxa (species and subspecies); protoglobigerinids also occurred. Most specimens belonged to the suborder Spirillinina, followed by the suborder Lagenina and Rotaliina; agglutinated forms were subordinate and miliolids were absent. The majority of the species have wide stratigraphic ranges; moreover, the distributions of 11 species changed based on their appearances in this section. Nevertheless, the Aalenian and Bajocian parts of the section could be distinguished based upon the stratigraphic distributions of some species.

Aalenian–Lower Bajocian Foraminiferal Fauna from the Ammonitico Rosso Series of Bakonycsernye (Hungary). Part 1: Taxonomy and Biostratigraphy

New collecting from the Middle Jurassic beds of the classic Bakonycsernye locality yielded very rich ammonite assemblages from the topmost Aalenian and the Lower Bajocian. A single bed, called here the Ovale Bed gave a high diversity Fissilobiceras ovale Zone fauna, with several stratigraphically diagnostic species and rich representation of early otoitids and stephanoceratids. These latters include topotypes of species described in classic monographs from this place. Here the earliest otoitids and stephanoceratids, Docidoceras wysogorskii and Westermannites chocsinskyi, respectively, appear first in beds belonging into the Graphoceras concavum Zone. The type horizon of W. telegdirothi, the best-known stephanoceratid from Csernye, most probably is within the Hyperlioceras discites Zone. Two new species are described, the otoitid Trilobiticeras (Emileites) kecskemetii n.sp. and the stephanoceratid Mollistephanus ottiliae n.sp., both form the Ovale Bed. Faunal affinities and the early development of the Otoitidae and Stephanoceratidae are discussed.

Ammonites from the Lower Bajocian (Middle Jurassic) beds of the classic locality of Bakonycsernye (Transdanubian Hungary), with special regard to the early otoitids and stephanoceratids

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Ammonites from the Lower Bajocian (Middle Jurassic) beds of the classic locality of Bakonycsernye (Transdanubian Hungary), with special regard to the early otoitids and stephanoceratids