Bennettitales from the Grisethorpe Bed (Middle Jurassic) at Cayton Bay, Yorkshire, UK

Middle Jurassic fossil plants from the Grisethorpe Bed at Cayton Bay and Grisethorpe Bay, Yorkshire, UK, are preserved in a soft claystone, and plant mesofossils recovered by sieving reveal excellent details of external structure. Studies of these mesofossils complement previous work on macrofossils from the Grisethorpe Bed and allow the plant fossils in this classic flora to be studied in a similar way to those preserved in Cretaceous mesofloras. Bennettitales, a key group in discussions of how angiosperms may be related to other seed plants, are especially well represented among mesofossils from the Grisethorpe Bed. Abundant bennettitalean leaves, scale leaves, and fragments of pollen and ovulate organs provide new information on these extinct plants. In particular, a specimen of Williamsoniella coronata (presumed aborted) shows only weak differentiation between interseminal scales and ovules and provides further evidence of homology between these structures.     

Middle Jurassic (upper Bajocian) marine vetigastropods from the Western Saharan Atlas,Algeria

Whereas Middle Jurassic gastropods are very well known in Europe and other regions of the world, these faunas have been much less studied from northern Africa and most contributions available in literature have been based on relatively well-preserved material. Except a little lower Bajocian fauna from the Central High Atlas (Morocco) described at the turn of the 21th century, nothing is known about the Middle Jurassic gastropods of the southwestern Tethyan margin. The present paper aims to update the systematics of two vetigastropod species: Obornella cf. granulata (Sowerby, 1818) and Ambercyclus ornatus (Sowerby, 1819) recently found in the upper Bajocian succession of the Ksour Mountains (Tniet el Klakh Formation) at western Saharan Atlas (northern Algeria). The new Ambercyclus material found in well-preserved conditions confirms the absence of umbilicus in Ambercyclus; thus, we emend the original generic diagnosis. The specimens of Obornella cf. granulata and Ambercyclus ornatus represent the first occurrence of both genera and species in the upper Bajocian marine deposits of the western Saharan Atlas, and provide new taxonomic and palaeobiogeographic information about Middle Jurassic vetigastropods in Algeria.     

Callovian (Middle Jurassic) marine microplankton from southwestern Germany: Biostratigraphy and paleoenvironmental interpretations

Late Middle Jurassic dinoflagellate cyst assemblages are documented from a section in Kandern and in samples from additional localities in southern Germany. The changes in the composition of the marine microfloras through the Callovian sections are related to fluctuations in sea-levels and changes in depositional environments. The Lower Callovian claystones, which represent inner shelf, soft bottom deposits, contain rich, diverse and well preserved dinoflagellate cyst assemblages. In the Kandern section a marked transition from the Lower Callovian claystone facies to the Anceps-oolite occur within the Calloviense zone. This transition was caused by a regression, and coincides with the LZA−3.1/LAZ−3.2 boundary on the cycle chart of Haq et al. (1987). Diverse dinoflagellate cyst assemblages also occur in the Anceps-oolite, but they are not so abundant as the acritarchs which dominate the overall palynofloras. The Anceps-oolite is interpreted as representing an offshore, but shallow marine environment. The transition to the overlying Upper Callovian “Renggeri Clay” is more gradual, but accompanied by marked changes in the overall composition of the marine microfloras. The “Renggeri Clay”, which represent an outer shelf, soft bottom depositional environment, shows a higher species diversity and abundance of dinoflagellate cysts than the underlying sequences. The distribution pattern of selected species through the Kandern section indicates that some species were related to specific environments, i.e. open marine forms, and that others could have been opportunistic forms, tolerating more shallow marine environments.

The distribution of the dinoflagellate cysts from southern Germany is related to the standard Northwest European ammonite zonation. The ranges of selected biostratigraphic key species are compared with ranges previously reported from the British and northwest European Jurassic. There are several discrepancies with respect to the earliest appearance and extinction datums, the only relevant Callovian palynostratigraphic “events” coinciding in southern Germany and Britain being: The extinction of Aldorfia aldorfensis at the top of the Calloviense zone, and the earliest incoming of Belodinium spp. and Liesbergia scarburghensis at the base of the Lamberti zone.     

Pterosaur and dinosaur remains from the Middle Jurassic Balabansai Svita in the northern Fergana Depression, Kyrgyzstan (Central Asia)

Abstract: Isolated pterosaur and dinosaur teeth and a sauropod metatarsal I and manual phalanx V-1 from the Middle Jurassic (Callovian) Balabansai Svita in the northern Fergana Valley, Kyrgyzstan, are described and attributed to the pterosaur taxon Rhamphorhynchinae indet., a theropod Tetanurae indet., a sauropod Neosauropoda indet., and a new pachycephalosaurid Ferganocephale adenticulatum gen. et sp. nov. The Balabansai theropod is possibly a stem-lineage representative of Dromaeosauridae. The new pachycephalosaurid is the oldest representative of the group and extends its known history by 10–20 myr. The Balabansai vertebrate assemblage is most similar to the Callovian assemblages from the Qigu and Upper Shaximiao formations in China, and intermediate in the evolutionary level of the taxa present between the Bathonian assemblages from Wucaiwan and the Lower Shaximiao formations (China) and the Late Jurassic Shar Teg fauna from Mongolia.     

Fossil coniferous wood from the Middle Jurassic of Liaoning Province, China

Silicified coniferous wood was collected from the Lanqi Formation (late Middle Jurassic in age) at Shebudaigou Village, Liaoning Province, China. Three taxa are identified, namely Pinoxylon dacotense Knowlton, Xenoxylon phyllocladoides Gothan, and Araucariopitys sp. Based on these new data, and those of other fossil plants reported previously from the same formation, we consider the climate during the deposition of the Lanqi Formation was subtropical, humid and seasonal. In this respect the Lanqi flora differs from the coeval Shimengou and Longmen floras from North China. The Longmen flora was deposited during more humid, subtropical conditions, while the Shimengou Formation indicates that the climate was warm temperate and dry. Our data would suggest that the Late Jurassic climatic pattern was initiated as early as the late Middle Jurassic.     

Cyrtocrinids (Crinoidea) and associated stalked crinoids from the Lower/Middle Oxfordian (Upper Jurassic) shelfal deposits of southern Poland

Five cyrtocrinid crinoid taxa previously unknown from the epicratonic deposits of Poland, as well as associated millericrinids and isocrinids, are described. The studied materials were derived mainly from the Lower and Middle Oxfordian, but crinoids are also from uppermost Callovian and/or lowermost Oxfordian sediments of the Polish Jura Chain (southern Poland). The crinoids, preserved as more or less complete (e.g., basal circlets) cups, include Lonchocrinus dumortieri, Phyllocrinus belbekensis, Remisovicrinus polonicus, Remisovicrinus aff. polonicus, Tetracrinus moniliformis and Sclerocrinus sp. The occurrence of Remisovicrinus polonicus in the late Middle Oxfordian of the southern Poland is confirmed. Moreover, the present study extends the geographic range of all cyrtocrinid species studied and discusses their unusual environmental adaptations.     

Vladimariales ordo nov. (Gymnospermae) from the Middle Jurassic deposits of the Mikhailovskii rudnik locality (Kursk Region,European Russia)

Composite seed-bearing capsules (formed by fusion of eight radially arranged elementary capsules), assigned to a new monotypic order Vladimariales ordo nov., were found in the Upper Bathonian deposits of the Mikhailovskii rudnik locality (Zheleznogorsk town, Kursk Region). In its morphology, the new order demonstrates valuable, phylogenetically conditioned similarity to Peltaspermales and Umkomasiales, but it is evolutionarily more advanced than these latter. A base of the composite capsule is supported by a collar on a stalk, which in external appearance is not different from collar of Ginkgo L., but has stalk, vascularized in a different way (its conducting tissue consisted of eight radially arranged collateral vascular bundles; each vascular bundle correspond to one of eight fused elementary capsules, each of which contain a solitary seed). Capsules and seeds are inverted relative to the collar; as a result, collar protects micropilar tips of seeds. The presence of collar and whole aspect of the new plant composite capsules give them the significant superficial similarity with seed-bearing organs of modern Ginkgo. Mature composite capsule in Vladimariales ordo nov. dehisced along the lines of fusion of elementary capsules, forming the composite capsule, and scattered seeds; opened composite capsule detached from axis. The significance of the new order for gymnosperm phylogeny is discussed.     

Bone histology of the Middle Jurassic turtle shell remains from Kirtlington, Oxfordshire, England

The Middle Jurassic (Bathonian) turtle material from the Mammal Bed at Kirtlington, Oxfordshire, England, has recently been tentatively referred to the Pleurosternidae, although the known synapomorphies of this clade were absent from the specimens. Here we present new evidence from shell bone histology that corroborates reports of pleurosternids at Kirtlington and further reveal that two different histomorphs (= two different taxa) are present in this locality. The first histomorph presents the distinctive histological structure of pleurosternids, which is described herein for the first time: the external cortical bone layers are differentiated into an inner zone of coarse, irregularly interwoven structural fibre bundles and an outer fine-fibred zone. The second histomorph has a more plesiomorphic structure and can only be assigned to Cryptodira indet. A morphological reassessment of the Kirtlington material fails to recognize two different taxa and shows that only sparse evidence supports the presence of pleurosternids in this locality. Shell bone histology thus appears as a powerful tool to study poorly preserved specimens and may in some case (like with pleurosternids) help resolve phylogenetic relationships. According to our results, the stratigraphic appearance of the Pleurosternidae is adjusted from the Kimmeridgian (Late Jurassic) to the Bathonian (Middle Jurassic), which significantly reduces the ghost lineage of Paracryptodira.     Bone histology, turtles, Paracryptodira, Pleurosternidae, Middle Jurassic, Kirtlington.     

Turtle remains from the Middle Jurassic Xintiangou Formation of Yunyang,Sichuan Basin,China

Three turtle shells from the Middle Jurassic Xintiangou Formation of Yunyang (Chongqing, China) are described and assigned to Xinjiangchelyidae (Testudines: Eucryptodira). This is the first report of turtle remains from the Xintiangou Formation, Sichuan Basin and represents the oldest known Xinjiangchelyidae. The assemblage includes two taxa, Protoxinjiangchelys sp. and Xinjiangchelyidae indet. This discovery extends the stratigraphical distribution of Xinjiangchelyidae and improves our knowledge about the early evolution of that family. It demonstrates that by the Middle Jurassic, at the time of deposition of the Xintiangou Formation, the group was already diversified in the Sichuan Basin.     

Calcareous nannofossils of the Cenomanian/Turonian boundary interval from the Boreal Realm (Wunstorf,northwest Germany)

The Cenomanian/Turonian boundary interval (CTBI) is marked by an intense climatic warming presumably caused by large magmatic eruptions. This warming was characterised by one of the most prominent Mesozoic perturbations of the carbon cycle, the Oceanic Anoxic Event 2 (OAE2), which is marked by a well pronounced positive carbon isotope excursion (CIE). Sediments of the OAE2-interval often consist of organic rich black shales suggesting widespread bottom water anoxia during the CTBI. This study focuses on calcareous nannofossils from the CTBI of a European section (Wunstorf Core; northwest Germany). A total of 105 samples were examined for calcareous nannofossils using the settling technique. Eight bioevents (last occurrences: Corollithion kennedyi, Lithraphidites acutus; first occurrences: Rotelapillus biarcus, Corollithion exiguum, Eprolithus octopetalus, Eprolithus eptapetalus, Quadrum gartneri, Eiffellithus eximius) have been recognised throughout the middle Cenomanian to middle Turonian interval. With the exception of eleven samples preservation is moderate to good. Calcareous nannofossils are abundant (mean 2.0 billion specimens/g sediment) and highly diverse (mean 58 species/sample). Assemblages are dominated by Watznaueria spp. (32.3%), Prediscosphaera spp. (13.4%), Zeugrhabdotus spp. (11.2%) and Biscutum spp. (10.5%). Pre-OAE2 and also post-OAE2 nannofossil assemblages show high abundances of Biscutum spp. (～ 20%) indicative for stable mesotrophic conditions. The assemblages of the OAE2 itself are marked by high values for Watznaueria spp. and low frequencies of Biscutum spp. making oligotrophic conditions during the OAE2 likely. High absolute abundances of organic walled dinoflagellates and the occurrence of frequent stress tolerant nannofossil genera like Retecapsa spp. in the organic rich intervals suggest, however, a deposition of black shales enhanced by high primary productivity. Thus dinoflagellates and calcareous nannofossils are interpreted to reflect different seasonal signals during the time of black shale deposition. Short-term high fertile seasons allowed the blooming of the organic walled dinoflagellates whereas calcareous nannofossils dominated the longer oligotrophic seasons. The black shale deposition was supported by the formation of large amounts of organic matter during fertile seasons as well as by surface water stagnation during oligotrophic seasons.     

The callovian (Middle Jurassic) crinoids from northern Lithuania

Callovian strata in northern Lithuania (Papilė area) have yielded some crinoid taxa[Chariocrinus andreae (Desor),Balanocrinus berchteni Hess —Pugin,B. subteres (Münster inGoldfuss) andIsocrinus nicoleti (Desor)], which have not been described from this area. The only form known previously wasBalanocrinus pentagonalis (Goldfuss).Palaeocomaster jaegeri n. sp. is the first free-living crinoid recorded from the Callovian of eastern Europe. It is characterized by possessing a very low, strongly flattened and narrow radial cavity. A very similar crinoid assemblage is known from the Callovian glacially-derived clays exposed in the Łuków region (eastern Poland), which were originally located near the Baltic Sea during the Middle Jurassic. It is considered that the allochthonous Callovian deposits from Poland are facies equivalents of the deposits known from Lithuania. The sole significant exception is the domination of free-moving comatulids (Comatulida) in the sediments known from the Papilė region, which may suggest that the Lithuanian sea basin was a little shallower than that located farther west in the Baltic area.      

Middle to Late Jurassic radiolarians from Sicily (Italy)

Middle and Upper Jurassic radiolarian faunas from two sections of Sicily are compared with the previously proposed zonations. The ages of the faunas are estimated by correlation with these zonations and by concurrent range zone. The faunas could be assigned to the Bathonian or earlier late Tithonian or early Berriasian. Two new spumellarian species (Bernoullius furcospinus andBernoullius rectispinus) from Middle Jurassic are described.     

Neoselachian sharks and rays from the British Bathonian (Middle Jurassic)

Extensive sampling of Bathonian sediments from localities across southern and central England has produced over 8000 neoselachian teeth. These comprise diverse faunas, with over 25 species being represented in total, most of them previously undescribed. Seventeen new species and seven new genera are named: Palaeoscyllium tenuidens sp. nov., Praeproscyllium oxoniensis gen. et sp. nov., Eypea leesi gen. et sp. nov., Proheterodontus sylvestris gen. et sp. nov., Paracestracion bellis sp. nov., Palaeobrachaelurus mussetti sp. nov., Heterophorcynus microdon gen. et sp. nov., Dorsetoscyllium terraefullonicum gen. et sp. nov., Ornatoscyllium freemani gen. et sp. nov., Pseudonotidanus semirugosus gen. et sp. nov., Synechodus duffini sp. nov., Protospinax magnus sp. nov., P. bilobatus sp. nov., P. carvalhoi sp. nov., Belemnobatis kermacki sp. nov., B. stahli sp. nov. and Spathobatis delsatei sp. nov. In addition, a new family, the Pseudonotidanidae fam. nov., is defined and the status of Paranotidanus Ward and Thies, 1987, Hybodus levis Woodward, 1889 and Breviacanthus brevis (Phillips, 1871) are discussed. These taxa show strong facies specificity, with different species being restricted to different palaeoenvironments.     

Evidence and cause of small size in Bathonian (Middle Jurassic) marine bivalves of north-western Europe

Data from the monographic literature indicate a general size reduction amongst Bathonian marine bivalves in southern England: mean size is reduced in all subclasses and major mode-of-life categories relative to the immediately preceding Bajocian stage (27 per cent. reduction) and the later Oxfordian stage (41 per cent. reduction). Smaller size cannot be explained in terms of sedimentary facies, nor as a 'pure' evolutionary phenomenon (involving no environmental change); it therefore probably reflects some quality of the ambient water. A comparable reduction in average size (19 per cent. relative to Bajocian, 46 per cent. relative to Oxfordian) is evident amongst oyster and scallop lineages studied throughout Europe and a sedimentary-facies (and pure evolutionary) control can be ruled out at least for an area extending from southern England to the east side of the Paris Basin. A lowering of salinity to the mid-twenties per mil is the likeliest cause of size reduction in this area. Isolation of the region from the oceans, combined with high fresh water runoff, was probably the determining factor in such widespread lowering of salinity. High runoff may have been caused by increased rainfall. Tests are proposed for the ubiquity of the pattern identified, and the suggested proximate and ultimate causes. It is noted that recognition of widespread reduced salinity has implications for the salinity tolerances of certain 'stenohaline-marine' taxa and the salinity ranges ascribed to certain nearshore faunal associations. In addition, recognition that environmentally determined size reduction may occur over a broad area has implications for the general issue of interpreting phyletic size change.     

On a longirostrine crocodylomorph (Thalattosuchia) from the Middle Jurassic of Tunisia

The geographic origins and distributional patterns of Gondwanan teleosauroids during the Jurassic have been fiercely debated over many years. Unlike the rich thalattosuchian fossil record from Laurasia, teleosauroids described from Gondwanan ecosystems are relatively scarce. Most of the known occurrences consist of isolated and fragmentary bones collected in Madagascar, Morocco, Tunisia, India, and Ethiopia. Nevertheless, these specimens, although fragmentary, have provided substantial information for assessing the evolutionary scenarios of multiple teleosauroid lineages and have shown that certain teleosauroid taxa were widespread rather than endemic to Western Europe. Here, a partial skeleton of a teleosauroid crocodylomorph is described. It was found in the late Middle Jurassic (Callovian) deposits of southeastern Tunisia by a team of French and Tunisian paleontologists; however, it has not been thoroughly studied at both macro- and microscopic scale until now. The new specimen is composed of an incomplete symphyseal portion of a lower jaw in addition to isolated teeth, osteoderms (both dorsal and ventral), thoracic and caudal vertebrae, and several thoracic ribs. The specimen has several morphological characters that are reminiscent of longirostrine teleosauroids. Due to the total absence of other cranial bones, as well as the pectoral and pelvic girdles, the specimen is not diagnostic to the generic level. However, these new remains represent the youngest ascertained occurrence of a definitive non-machimosaurin teleosauroid in Africa, provide additional insights into the geographic distribution of Thalattosuchia, and raise once again the question whether the origins of this clade were Gondwanan or Laurasian.     

A trace fossil assemblage from fluvial Old Red deposits (Wood Bay Formation; Lower to Middle Devonian) of NW-Spitsbergen, Svalbard

From the fluvial Old Red Sandstone (ORS) of the Lower to Middle Devonian Wood Bay Formation (NW-Spitsbergen), a diverse trace fossil assemblage, including two new ichnotaxa, is described: Svalbardichnus trilobus igen. n., isp. n. is interpreted as the three-lobed resting trace of an early phyllocarid crustacean (Rhinocarididae). Cruziana polaris isp. n. yields morphological details that point towards a trilobite origin. This occurence of presumably marine trace makers in a fluvial red bed sequence raises the question of whether we are dealing with marine ingressions that are not sedimentologically expressed, with homeomorphy, or with an adaptation of marine groups to non-marine environments.     

Bryozoan (Stenolaemata) records from the upper Callovian (Middle Jurassic) of the Moscow region

Encrusting bryozoans (Stenolaemata, Tubuliporida) discovered from upper Callovian deposits (Middle Jurassic) near the town of Kolomna in the Moscow region are described. They belong to two new species: Microeciella kolomnensis sp. nov. and Diplosolen akatjevense sp. nov. These bryozoans encrust a fragment of the large shell of cephalopod mollusk (ammonite), which is an unusual substrate not only for bryozoans but also for the other encrusting organisms.