COMPLEX BIOSTRATIGRAPHIC SCHEME OF THE JURASSIC DEPOSITS OF THE PIENNINE ZONE OF THE UKRAINIAN CARPATHIANS

The article summarizes the results of the study of paleontology and biostratigraphy of the Jurassic of the Piennine Zone of the Ukrainian Carpathians by domestic and foreign researchers. For the first time, a summary paleontological description of these sediments is presented, taking into account numerous published data on identified macro- and mictofossils. A correlation biozonal scale has been created, as well as complex biostratigraphic schemes for each Jurassic series of its region in accordance with the International Stratigraphic Scale (2020). Because the stratigraphic sequence was disturbed by disjunctive dislocations, these schemes were developed by analysis of fragmentary sections. At present, three series of the Jurassic are determined by ammonites, belemnites, pelecypods, brachiopods, the Lower and Upper series are also dated by dinocysts, the Upper also by foraminifera and tintinnids. The stages and standard zones of the modern international scale are determined by ammonites: Liasicus of the Gettangian; Bucklandi, Obtusum, Raricostatum of the Sinemurian; Jamesoni, Emaciatum of the Pliensbachian; Tenuicostatum, Serpentinum, Bifrons, Thouarcense of the Toarcien; Opalinum, Murchisonae, Bradfordensis, Concavum of the Aalenian; Propinquans, Humpriesianum, Parkinsoni of the Bajocian; Zigzag, Aurigerus, Subcontractus, Bremeri, Retrocostatum of the Bathonian; Athletа of the Callovian; Plicatilis і Bifurcates of the Oxfordian; Divisum, Acanticum і Cavouri of the Kimmeridgian. Continuous dinocyst zonation is traced in the Upper Jurassic – Fibrata Аcme (Upper Oxfordian), Parvula Acme, Moluccana і Borzai (Kimmerigian), Pulla, Tithonica, Malmica, Semiradiata (Lower Tithonian) and all standard tintinnide zones of Tithonian — Chitinoidella (підзони Dobeni і Boneti), Praetintinnopsella, Crassicollaria. The boundaries of the stages from the Gettangiean to the Oxfordian are not determined. The boundaries between the Lower and Upper Oxfordian as well as between the Kimmeridgian substages are determined by ammonites as well as the boundary between the Kimmeridgian and Tithonian is determined by dinocysts, and the boundary between the Jurassic and Cretaceous is determined by tintinnids (corresponds to the boundary between the zones Crassicollaria of Tithonian and Calpionella of Berriassian). Stratigraphic unconformities were revealed by the macro- and mictofossils: the regional erosion on the boundary between the Aalenian and Bajocian as well as in Early Callovian, and short gap on the boundary between the Lower and Upper Bajocian.

First record of an erymid lobster (Crustacea, Decapoda) from the upper Bajocian of Northwest Bulgaria

Fossil chela of an erymid lobster from a single locality of the upper Bajocian in the Western Fore-Balkan Mts (NW Bulgaria) was studied. Two segments of the thoracic appendages, probably belonging to one individual, were described: 1) P1 propodus with partially preserved pollex and dactylus; and 2) P1 carpus and P1 merus attached. These elements of the first pair of pereiopods of a lobster were identified as Eryma compressum (Eudes-Deslongchamps, 1842). Eryma compressum a is well-known taxon from numerous Jurassic localities in Europe but has not been recorded in Bulgaria to date. Therefore, albeit being an isolated finding with only a few elements, the Bulgarian example contributes to the overall record of European erymid faunas from the Middle Jurassic, and especially in Eastern Europe, from where only a few erymids have been reported.

New insights into the taxonomy and evolution of Jurassic planktonic foraminifera

Globuligerina glinskikhae nov. sp. Gradstein & Waskowska and Globuligerina waskowskae nov. sp. Gradstein are new species of Jurassic planktonic foraminifera from the Middle Jurassic of Dagestan and Poland. G. glinskikhae nov. sp. with its remarkable ‘protoglobigerine’ test may be an early evolutionary offshoot of Globuligerina oxfordiana (Grigelis). It may be an index taxon for upper Bajocian through Bathonian strata in Eastern Europe and Southwest Asia, and might be recognizable also in thin sections. We consider G. waskowskae nov. sp. to be a possible forerunner of Conoglobigerina helvetojurassica (Haeusler), the first planktonic foraminiferal species with a reticulate wall texture. Currently, is only known from Poland. In some localities, specimens of G. oxfordiana and of G. glinskikhae nov. sp. posses an additional apertural opening, often lacking a rim; its function is enigmatic. The postulated lineage from Jurassic Globuligerina balakhmatovae (Morozova) to Cretaceous Clavihedbergella eocretacea Neagu is refined with the description of Petaloglobigerina simmonsi nov. gen., nov. sp. Gradstein from the Kimmeridgian of Portugal. The evolutionary transition from G. balakhmatovae to P. simmonsi occurs by means of the ontogenic development of a petaloid test, with a pronounced flattening of the whorl with ovate chambers, the last ones often offset and twisted. Jurassic planktonic foraminifera, now known to consist of three genera and 12+ species underwent long periods of stasis, interrupted by late Bajocian, mid-Oxfordian and early Kimmeridgian evolution. The three ‘stasis and root’ taxa G. oxfordiana, G. bathoniana and G. balakhmatovae are geographically widespread in lower to mid palaeo-latitudes, and stratigraphically long ranging within the Middle and Late Jurassic. Modern digital microscopes, with co-axial and side LED lighting and excellent image stacking software are important tools in the study of Jurassic planktonic foraminifera, and fast and cost-effective communication tools in modern micropalaeontology.

Assessment of serpulid-hydroid association through the Jurassic: A case study from the Polish Basin

The coexistence of sessile, tube-dwelling polychaetes (serpulids) and hydroids, has been investigated. Serpulid tubes bearing traces after hydroids are derived from different stratigraphic intervals spanning the Middle and Upper Jurassic, the rocks of which represent the diverse paleoenvironments of the Polish Basin. Although fossil colonial hydroids classified under the species Protulophila gestroi are a commonly occurring symbiont of these polychaetes during the Late Cretaceous and Cenozoic, they seem to be significantly less frequent during the Jurassic and limited to specific paleoenvironments. The hydroids described here are represented by traces after a thin stolonal network with elongated polyp chambers that open to the outer polychaete tube’s surface with small, more or less subcircular apertures. Small chimney-like bulges around openings are an effect of the incorporation of the organism by in vivo embedment (bioclaustration) within the outer layers of the calcareous tube of the serpulid host. Considering the rich collection of well-preserved serpulid tubes (>3000 specimens), the frequency of bioclaustrated hydroids is very low, with an infestation percentage of only 0.6% (20 cases). It has been noticed that only specimens of the genus Propomatoceros from the Upper Bajocian, Lower Bathonian, Middle Bathonian, and Callovian have been found infested. However, the majority of bioclaustrated hydroids (17 cases) have been recorded in the Middle Bathonian serpulid species Propomatoceros lumbricalis coming from a single sampled site. Representatives of other genera are not affected, which is congruent with previous reports indicating that Protulophila gestroi was strongly selective in the choice of its host. A presumably commensal relationship is compared with the recent symbiosis between the hydroids of the genus Proboscidactyla and certain genera of sabellid polychaetes.

Ammonite occurrences in North Sea cores: implications for Jurassic Arctic–Mediterranean marine seaway connectivity

The paucity of ammonite recovery from North Sea wells has meant that offshore correlations are largely dependent upon microfossil assemblages. While rare, ammonites have been found in a few boreholes during the course of oil exploration activities. The occurrence of ammonites in ten wells in the UK sector of the Viking Graben and the Moray Firth rift arms provides a new basis by which to demonstrate that there was a distinct separation between Arctic and sub-Mediterranean species that lasted from Bajocian to Early Callovian times. Five wells contain ‘Boreal Bathonian' ammonites from the Arctic Realm. Arctocephalites from the Boreal Arcticus Zone (uppermost Bajocian) correlates basinal partly anoxic mudstones in the Beryl Embayment (9/13b) with both bioturbated siltstones in the southern Viking Graben (9/10b), and calcareous mudstones in the East Shetland Basin (211/21). Upper Bajocian Pompeckji Zone Cranocephalites and younger Arcticoceras from Lower to Middle Bathonian Greenlandicus, Ishmae and Cranocephaloide zones are confined to 211/21 demonstrating that the marine transgression began earlier and lasted longer. A Cadoceras from well 3/3-8 dates to the Lower Callovian Koenigi and Calloviense zones during which renewed extensional faulting re-established ammonite migration routes between the Boreal and sub-Mediterranean realms. A Middle Oxfordian (Densiplicatum Zone) Perisphinctes from well 22/5b-8 confirms an episode of northward migration from the sub-Mediterranean into the Boreal Realm. Upper Oxfordian (Regulare to Rosenkantzi zones) Amoeboceras in wells 211/21-1 and 9/13b-19 are close to Upper Bajocian/Lower Bathonian faunas, suggesting an absence of Upper Bathonian to Middle Oxfordian strata as a result of rift-related footwall uplift and erosion. In four wells from Block 15/21 (-4, -11, -12A and -25) Lower Kimmeridgian ammonites have been documented, including Rasenia, Amoebites, Aulacostephanoides and Zenostephanoides, from the Baylei (?), Cymodoce, Mutabilis and Eudoxus zones, the latter (confirmed at well 13/28b-8) dating a widespread regional marine flooding surface in the Inner Moray Firth.Supplementary material: The detailed measurements of dimensions of the ammonites described are available at: https://doi.org/10.6084/m9.figshare.c.5087313