Parataxonomy and palaeobiogeographic significance of dinosaur eggshell fragments from the Upper Cretaceous strata of the Cauvery Basin,South India

Abstract

In the past, fossilised dinosaur eggshells have been extensively documented from the Upper Cretaceous Lameta Formation of Central India and as many as nine oospecies are known at present from this formation. Compared to this, only one dinosaur oospecies has been described from the Cretaceous succession of the Cauvery Basin. However, the first fossil egg from India, identified as a chelonian egg, was documented from the Aptian – Albian Karai Formation of the Cauvery Basin in 1957. Following this, a solitary titanosaurid dinosaur egg was described from the Upper Cretaceous (Lower Maastrichtian) Kallankuruchhi Formation, Cauvery Basin in 1996. More recently, we have recovered isolated eggshell fragments from the marine part of the Upper Cretaceous (Late Maastrichtian) Kallamedu Formation. Based on eggshell morphology, microstructure and ultrastructure, these eggshell fragments are assigned to the oospecies Fusioolithus baghensis. The new find from the Cauvery Basin is important from palaeobiogeographic point of view as the oofamily Fusioolithidae is found in the Upper Cretaceous strata of India, France, Argentina and Morocco. Based on the common occurrence of similar oospecies in South America, Africa, Europe and India, a Late Cretaceous palaeobiogeographic connection between India and South America as well as Europe via Africa is suggested.     

Dating the “red beds” of the Eastern Moroccan High Plateaus: Evidence from late Late Cretaceous charophytes and dinosaur eggshells

A new locality in the poorly known “red beds” of Tendrara (High Plateaus, Morocco) has yielded four charophytes species (Feistiella anluensis, Lamprothamnium stipitatum, Peckisphaera portezueloensis, Platychara caudata) and dinosaur eggshells (Pseudomegaloolithus atlasi). These red beds, which overly the Cenomanian-Turonian marine deposits, generally assigned to “Senonian” based on geometric position, are directly dated by these fossils: the charophytes species and dinosaur oospecies association indicates a Campano-Maastrichtian or Maastrichtian age for these calm floodplain deposits.     

Otolith chemistry of prey fish consumed by a fish predator: does digestion hinder Russian doll techniques?

The effect of digestion by a predatory fish (largemouth bass Micropterus salmoides) on stable isotopic (δ¹³C and δ¹⁸O) and trace elemental (Sr:Ca and Ba:Ca) compositions of prey fish (bluegill Lepomis macrochirus) otoliths was investigated in a laboratory experiment. Trace element and stable‐isotopic signatures of L. macrochirus otoliths were not significantly altered for up to 16 h after L. macrochirus were consumed by M. salmoides. Prey fish otoliths recovered from predator digesta can retain environmental stable isotopic and trace elemental signatures, suggesting that determination of environmental history for prey fishes by stable‐isotope and trace‐element analysis of otoliths recovered from stomachs of piscivorous fishes will be feasible.     

A new oospecies of Similifaveoloolithidae from the Xiuning Basin,Late Cretaceous of Anhui,China

Well-preserved dinosaur eggs from the Cretaceous Huizhou Formation in the Xiuning Basin, Anhui Province, China, are analysed in this paper. We describe a new oospecies, Similifaveoloolithus qiyunshanensis, based on several distinct characters of external morphology, size, eggshell thickness, and internal microstructure. Radial sections of this new oospecies show branched eggshell units with a fused layer near the outer surface, while numerous irregular pores and cones constitute a honeycomb pattern in tangential sections. The discovery of S. qiyunshanensis expands the distribution of Similifaveoloolithidae dinosaur eggs in China and provides new fossils for researching dinosaur eggshell formation mechanisms which are different from those of the currently known oofamilies. The dinosaur-egg-bearing strata in the Huizhou Formation have been dated to the early Late Cretaceous (Cenomanian-Turonian) on the basis of a similar dinosaur egg assemblage in the Tiantai Basin in Zhejiang Province. The eggs described in this paper are thought to have been laid in a buried nest while enrichment of trace elements in eggshells may have been caused by their ingestion into the body of the dinosaur producer. We suggest that the paleoclimate of this habitat was semi-arid to arid and that this environment was favourable for the preservation of eggs.http://zoobank.org/LSIDurn:lsid:zoobank.org:pub:9D63A51F-5A4B-4249-901D-42A33E9FA933     

The first record of a dinosaur from Bulgaria

Mateus, O., Dyke, G.J., Motchurova-Dekova, N., Kamenov, G.D. & Ivanov, P. 2010: The first record of a dinosaur from Bulgaria. Lethaia, Vol. 43, pp. 88–94.
A portion of a left humerus from the Upper Maastrichtian of Vratsa district (NW Bulgaria) is shown to be from a non-avian theropod dinosaur: this is the first record of a dinosaur from Bulgaria. We describe this bone, suggest that it most likely pertains to an ornithomimosaur, and discuss the fossil record of other similar taxa of Late Cretaceous age that have been reported from Europe. To investigate the taphonomy of this fossil, rare earth element (REE) analysis is combined with strontium (Sr) isotope data to confirm that this Bulgarian dinosaur bone was initially fossilized in a terrestrial environment, then later re-worked into late Maastrichtian marine sediments. □ Bulgaria , Dinosauria , Late Cretaceous , Ornithomimosauria , rare earth elements , Sr isotopes , taphonomy , Theropoda .     

Structure of fossil dinosaur eggshell from the Aix Basin,France

At least four types of dinosaur eggshell are distinguished among samples of fossil eggshell from Late Cretaceous deposits of southern France. Recognition is based on shell microstructure, porosity, and shell thickness. Estimated values of water vapour conductance for these dinosaur eggshells are much greather than predicted for avian eggs, suggesting that the eggs were incubated under conditions of high humidity, such as would occur underground.     

Titanosaur eggshells from the Tremp Formation (Upper Cretaceous,Southern Pyrenees,Spain)

Hundreds of megaloolithid eggshells have been found at the Costa de la Coma site (Tremp Fm, South-Central Pyrenees, Spain), the microstructural features (spherulitic eggshell units, thickness, ornamentation and pore system) of which agree with the Megaloolithus oogenus diagnosis. Comparisons with other megaloolithids from the Tremp Basin, southern France and South America, however, showed that these eggshells share many features with the South American oospecies Megaloolithus patagonicus. A cladistic analysis of the qualitative eggshell features of the main dinosaur taxa was performed. The results grouped the Costa de la Coma eggshells with Megaloolithus patagonicus, forming a clade separated from other megaloolithids, and revealed a polytomy of megaloolithids (associated with sauropods) and spheroolithids (associated with hadrosaurs). The finding of Megaloolithus cf. patagonicus in the Tremp Fm agrees with skeletal evidence provided by four indeterminate titanosaur forms from the Formation's late Cretaceous deposits. Other Megaloolithus oospecies of the Tremp Fm may belong to hadrosaurs, the skeletal remains of which are also abundant in the Tremp Basin.     

Two new theropod egg sites from the Late Jurassic Lourinhã Formation,Portugal

Two new Late Jurassic (uppermost Late Kimmeridgian) dinosaur eggshell sites are described, Casal da Rola and Porto das Barcas, both near Lourinhã, central-west Portugal. Casal da Rola yields eggshells with an obliquiprismatic morphotype comparable to those from a nest with the associated fossil embryos from Paimogo, tentatively assigned to the theropod Lourinhanosaurus antunesi. The Porto das Barcas eggshells have a dendrospherulitic morphotype with a prolatocanaliculate pore system. This morphotype was also recognised in eggshells from a clutch with associated Torvosaurus embryos at the Porto das Barcas locality. A preliminary cladistic analysis of eggshell morphology suggests theropod affinities for the Casal da Rola eggs, but is unable to resolve the phylogenetic position of the Porto das Barcas eggs. The eggshells at both sites are preserved in distal flood plain mudstones and siltstones. Carbonate concretions within the deposits indicate paleosol development.     

Did central Australian megafaunal extinction coincide with abrupt ecosystem collapse or gradual climate change?

Aim In central Australia, the giant flightless bird Genyornis newtoni disappeared about 45–50 thousand years ago (ka). It has been reported that coincident with this extinction the carbon isotopic composition of preserved eggshells of the extant emu (Dromaius novaehollandiae) shows an abrupt dietary shift from tropical grasses (C₄ photosynthesis) to temperate grasses and/or woody browse (C₃ photosynthesis). This abrupt shift has been interpreted as signalling ‘ecosystem collapse’ due to landscape burning by humans. We evaluate an alternative interpretation, that the shift in diet was not abrupt, but gradual, and caused by the weakening of the Australian monsoon. Location Lake Eyre, central Australia. Methods We re‐analysed a large, published dataset of emu diet δ¹³C (inferred from δ¹³C of preserved eggshells) spanning the last 140,000 years, using time‐series analysis. Using Akaike's information criterion, we compared two contrasting models: (1) there was an abrupt shift in δ¹³C coincident with the extinction of Genyornis, assumed 47.5 ka; and (2) there was a gradual shift in δ¹³C, correlated with reconstructed water level in Lake Eyre, a proxy for monsoon intensity. Results There was little evidence of an abrupt shift in emu diet δ¹³C about 45–50 ka, but δ¹³C appeared to steadily decrease between about 80 and 30 ka. Indeed, the model representing a correlation between δ¹³C and lake level was more than seven times more likely than the model representing an abrupt shift at 47.5 ka. Main conclusions The emu eggshell isotopic record from Lake Eyre does not support the hypothesis that landscape burning by humans transformed a savanna?grassland mosaic into the modern desert scrub, contributing to the extinction of Genyornis. While our findings cast strong doubt on the foremost line of evidence that landscape burning by humans caused the megafaunal extinctions, and suggest that central Australia was becoming increasingly arid in the Late Pleistocene, the relative roles of hunting by humans and climate change in the megafaunal extinctions remain unresolved.     

A new peculiar dinosaur egg,Sankofa pyrenaica oogen. nov. oosp. nov. from the Upper Cretaceous coastal deposits of the Aren Formation,south‐central Pyrenees,Lleida, Catalonia,Spain

Abstract: A new type of small, ovoid dinosaur egg, Sankofa pyrenaica oogen. nov. oosp. nov., with a prismatic type eggshell is described from upper Cretaceous (upper Campanian–Maastrichtian) deposits of the Montsec area, South Pyrenean Central Unit, Lleida, Catalonia, Spain. This egg type was sub‐vertically laid in only two rich monospecific sites of a single stratigraphic layer from coastal deposits of the Aren Formation, interpreted as an emerged beach ridge of a barrier island – lagoon depositional system. The size and shape of these eggs with their asymmetric poles are roughly similar to modern hen eggs, which is unusual in the Cretaceous fossil egg record. Its phylogenetic position clusters with bird and Troodontid eggs. A morphospace analysis of egg shapes shows the similarity of the new egg to a Campanian fossil bird egg from Argentina, both being intermediate between modern‐bird eggs and extinct nonavian theropod eggs. However, the eggshell microstructure of Sankofa pyrenaica differs from that of bird eggs in its incipient squamatic texture. It has a peculiar pattern of interlocking small crystals in the middle of the palisade layer, instead of the thick squamatic structure commonly present in modern avian eggshells. This new egg type is attributed to a small theropod, probably with a single oviduct like birds and whose mosaic distribution of features is a combination between that of birds and nonavian theropods. This enhances the arguments supporting the close phylogenetic relationships between both groups.     

Asteriscus v. lapillus: comparing the chemistry of two otolith types and their ability to delineate riverine populations of common carp Cyprinus carpio

The chemical composition of common carp Cyprinus carpio asteriscus (vaterite) and lapillus (aragonite) otoliths from the same individual and reflecting the same growth period was measured to (1) determine whether there are differences in the uptake of trace metals (Mg:Ca, Mn:Ca, Sr:Ca and Ba:Ca ) and Sr isotope ratios (⁸⁷Sr:⁸⁶Sr) in co‐precipitating lapilli and asterisci and (2) compare the ability of multi‐element and isotopic signatures from lapilli, asterisci and both otolith types combined to discriminate C. carpio populations over a large spatial scale within a river basin. Depth profile analyses at the otolith edge using laser‐ablation inductively coupled plasma mass spectrometry showed that asterisci were enriched in Mg and Mn and depleted in Sr and Ba relative to lapilli, whilst ⁸⁷Sr:⁸⁶Sr values were nearly identical in both otolith types. Significant spatial differences among capture locations were found when all trace element and Sr isotope ratio data were aggregated into a multi‐element and isotopic signature, regardless of which otolith type was used or if they were used in combination. Discriminatory power was enhanced, however, when data for both otolith types were combined, suggesting that analysis of multiple otolith types may be useful for studies attempting to delineate C. carpio populations at finer spatial or temporal scales.     

Determining the sources of calcium for migratory songbirds using stable strontium isotopes

We investigated natural variations in the stable isotopic composition of strontium (a surrogate for calcium) in the bones of a single species of breeding migratory songbird, as well as in their eggshells, egg contents, and food sources. We use this information to determine the sources of calcium to these migratory songbirds and their offspring. Samples were collected from two locations in the northeastern USA (Hubbard Brook, NH, and Downer Forest, VT.) that differed in soil geochemistry. The mean ⁸⁷Sr/⁸⁶Sr ratios of food items (caterpillars and snails), eggshells, and egg contents were indistinguishable within each site, but significantly different between the two sites. Mean ⁸⁷Sr/⁸⁶Sr ratios for the bones of adult females were significantly different between the two sites, but values were significantly lower than those of food items and eggshells at each site. Two of four adult individuals studied at each site had ⁸⁷Sr/⁸⁶Sr ratios lower than the entire range of values for local food sources. Mixing calculations indicate that up to 60% of skeletal strontium and calcium was derived from foods consumed in the winter grounds where lower ⁸⁷Sr/⁸⁶Sr ratios predominate. At each study site, the ⁸⁷Sr/⁸⁶Sr ratio of eggshells differed significantly between clutches, but the mean clutch ⁸⁷Sr/⁸⁶Sr ratios were unrelated to the skeletal ⁸⁷Sr/⁸⁶Sr ratio of the laying adult. These findings suggest that strontium (and hence calcium) for eggshell production in this species is derived predominantly from local food sources in breeding areas. Thus, reductions in available calcium in northern temperate ecosystems due to the influences of acid deposition could be potentially harmful to this and other species of migratory bird.     

Morphometric analysis of dinosaur eggshells: constraints of size on shape

Studies on fossil eggs and eggshells have been traditionally focused on analysis of microstructure and systematic classification, but few attempts have been made to examine the variability of eggshell characters. This work examines the variability of one diagnostic character, shape of the calcitic units, of some dinosaur eggshells by using outline shape analysis (elliptic Fourier analysis). The studied material belongs to five different oospecies of the parafamily Megaloolithidae Zhao, 1979. To test shape variation within and between oospecies, an analysis on 129 outlines was carried out and their variability was summarised by principal component analysis. We then tested if the shape of megaloolithid units changes according to size (i.e. allometry). A regression analysis between eggshell unit shape and two different size measurements (centroid size and eggshell thickness) showed that the thinnest eggshells (thickness ≤ 1 mm) have different shapes than thicker ones ( ≥ 2.5 mm). Our results stress that the variability in the shape of eggshell units in Megaloolithus oospecies is correlated to size (i.e. eggshell thickness), a phenomenon that should be then considered carefully when determining oospecies, since a single oospecies can show both a wide range of eggshell thickness and combined with different eggshell unit shapes.     

Otolith trace element and stable isotopic compositions differentiate fishes from the Middle Mississippi River, its tributaries, and floodplain lakes

Naturally occurring stable isotope and trace elemental markers in otoliths have emerged as powerful tools for determining natal origins and environmental history of fishes in a variety of marine and freshwater environments. However, few studies have examined the applicability of this technique in large river-floodplain ecosystems. This study evaluated otolith microchemistry and stable isotopic composition as tools for determining environmental history of fishes in the Middle Mississippi River, its tributaries, and floodplain lakes in Illinois and Missouri, USA. Fishes were collected from 14 sites and water samples obtained from 16 sites during summer and fall 2006 and spring 2007. Otolith and water samples were analyzed for stable oxygen isotopic composition (δ¹⁸O) and concentrations of a suite of trace elements; otoliths were also analyzed for carbon isotopic composition (δ¹³C). Tributaries, floodplain lakes, and the Mississippi and Lower Missouri Rivers possessed distinct isotopic and elemental signatures that were reflected in fish otoliths. Fish from tributaries on the Missouri and Illinois sides of the middle Mississippi River could also be distinguished from one another by their elemental and isotopic fingerprints. Linear discriminant function analysis of otolith chemical signatures indicated that fish could be classified back to their environment of capture (Mississippi River, floodplain lake, tributary on the Illinois or Missouri side of the Mississippi River, or lower Missouri River) with 71–100% accuracy. This study demonstrates the potential applicability of otolith microchemistry and stable isotope analyses to determine natal origins and describe environmental history of fishes in the Middle Mississippi River, its tributaries, and floodplain lakes. The ability to reconstruct environmental history of individual fish using naturally occurring isotopic markers in otoliths may also facilitate efforts to quantify nutrient and energy subsidies to the Mississippi River provided by fishes that emigrate from floodplain lakes or tributaries.     

BIOMECHANICAL PROPERTIES OF DINOSAUR EGGSHELLS (Ⅱ)──TWO BREAKING TYPES OF THE DINOSAUR EGGSHELLS UNDER EXTERNAL PRESSURE

Thedinosaursburytheireggsinsandorearthforincubation.Assumingthatexertingexterna1forcesontheseeggswithinthenestareequa1distributionpressure,i.e.NQo=NBdi=O.Aftertreatingthestatisticalfiguresofthedinosaureggshe-lls,anon-dimensiona1contourcurveforinulacanbeobtained:inwhichUsingnumericalmethodsubstitutesthedifferentialwithcentraldifference:Thusthethreedifferenceexpressionsofcurvatureradiusoftheeggshe1lcanbeobtained:Usingnondimensionparameters:inwhichNoandNearenondimensi0nalinternalf0rcesal0ngth…     

Sediment and eggshell interactions: using abrasion to assess transport in fossil eggshell accumulations

Recent excavation at the Late Cretaceous Egg Mountain locality in Montana revealed abundant Spheroolithus eggshell fragments. The depositional history of the fragments is problematic due to the vertical dispersal of eggshell in homogeneous mudstone. The results of previous studies assessing eggshell transport are based on thin, modern eggshell occurring on well-defined horizons. Therefore, the assessment of depositional history required a different method. Chicken (Gallus gallus domesticus) and ostrich (Struthio camelus) eggshells were placed in a tumbler with water and quartz sand for 168–504 h to simulate transport. The resulting wear on these fragments, revealed under scanning electron microscope, was compared to unabraded eggshell. In addition, the modern eggshell was compared to fossil eggshells from a nesting site, crevasse splay and channel deposits, and Egg Mountain. Fossil eggshells from high-energy paleoenvironments display similar edge rounding to modern eggshell placed in the tumbler. In contrast, eggshell from Egg Mountain lacked edge rounding and resembled fossil eggshell from a nesting site and unabraded modern eggshell, suggesting that the Egg Mountain locality represents a parautochthonous assemblage. This study indicates that sediment interaction leaves distinct patterns of abrasion on eggshell, which may be useful for assessing transport of eggshell at fossil localities.     

Carbon isotopic abundances in Mesozoic and Cenozoic fossil plants: Palaeoecological implications

Carbon isotopic abundances have been measured for more than one hundred samples of fossil plants ranging in age from middle Triassic to late Tertiary. Most of the plant fossils were identified at the specific or generic level and were selected as representing a variety of continental environments, including xeric and humid habitats. Material analysed included numerous fragments of flowers, seeds, fruits, leaves and wood, as well as a single amorphous lignite sample. The analyses performed for the plant fragments indicate relatively constant isotopic compositions during this time interval, with plant δ¹³C values ranging between -28 and -20%. These values are within the range for living terrestrial plants with C₃, photosynthesis, although values more positive than -23% are rare in C₃ plants and typically found in plants growing under environmental stress. Lower δ¹³C values might have been expected owing to the much higher CO₂, levels of the Cretaceous atmosphere that have been inferred from marine carbonates. No fossils with values indicating C₄, photosynthesis were discovered. Fossil plants from inferred mesic environments showed δ¹³C values ranging between -26.7 and -24.1%. Highest δ¹³C values in angiosperms (up to -20.1%) were measured for Late Cretaceous combretaceous flowers from Portugal. Some cheirolepidiaceous conifers from the Early Cretaceous also showed high δ¹³C values. Values measured for Pseudofrenelopsis varians and Glenrosa taxensis were -21.9%, and values of gymnosperm wood, probably of cheirolepidiaceous affinity, were -19.0%. These high values are in accordance with inferred ecological conditions for the fossil plants. They may suggest a tendency for C₄,-like photosynthesis, although the data are equivocal. Higher values (-17.3%) clearly falling outside the C₃, range were, however, obtained from a single lignite fragment of Late Cretaceous (Maastrichtian) age. The nature of this plant fragment is unknown, but the result suggests that C₄-like photosynthesis was present at least in some latest Cretaceous vegetation. A hadrosaurian dinosaur with well-preserved collagen-like organic matter from the same deposit showed δ¹³C values around-16%, which also suggests the presence of CAM or even C₄ plants in the latest Cretaceous. □Carbon isotopic abundances, δ¹³C values, dinosaurs, plants, photosynthetic pathways, Mesozoic.     

Allochthonous and autochthonous particulate organic matter in floodplains of the River Danube: the importance of hydrological connectivity

SUMMARY 1. The elemental composition, the proportion of living organic carbon and the carbon stable isotope signatures of particulate organic matter (POM) were determined in a large river floodplain system in order to elucidate the major carbon sources in relation to the hydrological conditions over a 13‐month period. 2. Two floodplain segments and the main channel of the River Danube downstream of Vienna (Austria), were compared on the basis of discharge and water age estimations. The more dynamic floodplain was connected to the main channel for 46% of the study period and drained up to 12% of total discharge at high water. 3. The mean C : N ratio and δ¹³C signature of the POM increased from the floodplain site that was more isolated from the river (6.6; ?33‰) to the main channel (8.4; ?25‰). At the dynamic floodplain site, the C : N ratio and the δ¹³C signature of the POM increased with hydrological connectivity (expressed as water age). 4. Only during flood events (4% frequency of occurrence), a considerable input of riverine POM was observed. This input was indicated by a C : N ratio of the POM pool of more than 10, the amount of detrital carbon (>80% of the total POM pool) and a δ¹³C signature of POM of more than ?25‰ in the dynamic floodplain. 5. Plankton derived carbon, indicated by C : N ratios less than eight and δ¹³C values lower than ?25‰, dominated the particulate organic carbon (POC) pool at both floodplain sites, emphasising the importance of local (autochthonous) production. Phytoplankton was the major plankton compartment at the dynamic site, with highest biomasses at medium water ages. 6. At the dynamic floodplain site, the Danube Restoration Project has enhanced the duration of upstream surface connection with the main channel from 4 to 46% frequency of occurrence. Therefore, the export of living POC to the main channel is now established during phases of maximum phytoplankton production and doubled the estimated total export of non‐refractory POM compared with prerestoration conditions.     

三种海鸟卵壳的超微结构和无机成分的研究

应用扫描电镜和ＴＮ－５５００能谱仪对三种海鸟卵壳的超微结构和基本无机元素进行研究分析,结果表明,基本结构相似,但表层突起和裂纹,乳锥和锥本形态,以及气孔在单位面积内的数量,壳膜与卵壳的锚连方式,壳膜元素组成等都存在着不同,这既反映其遗传,繁殖生理功能上的差异,也显示了不同种鸟卵壳之间的相似和相异性,因而对研究严分类和地理分布具有一定差异价值。     

Stable isotope records (O, C) of Jurassic aragonitic shells from England and NW Poland: palaeoecologic and environmental implications

Shells of fully marine Middle to Upper Jurassic molluscs from England and north-western Poland were analysed with respect to their stable isotope (δ¹⁸O, δ¹³C) compositions, and palaeoecological and environmental life conditions of these molluscs were inferred from them. Light microscopical and SEM inspection and an analysis of the minor element content (Fe, Mn, Mg, Sr) suggest rather unaltered isotope signals. The δ¹⁸O and δ¹³C values show a characteristic distribution among three groups of co-occurring organisms. Benthic (adult) bivalves generally preserved higher δ¹⁸O and δ¹³C values than ammonites, whereas planktic bivalve larvae tend to possess the lowest δ¹⁸O but higher δ¹³C than adult bivalves. As this distribution pattern is found in numerous horizons and sections of Bathonian to Kimmeridgian age in NW Poland and England, it is thought to reflect real palaeoenvironmental parameters. All observations can be incorporated in a single model that assumes (i) seasonally induced temperature stratification of the water column, (ii) a correlation between phytoplankton blooms and reproduction season of planktic-planktotrophic bivalves, and (iii) insignificant vital effects with respect to the δ¹³C in bivalves, but strong biological control in ammonites. In addition, the δ¹⁸O evolution suggests that the Late Bajocian to Middle/Late Bathonian and Early Oxfordian to Late Kimmeridgian were considerably warmer than the latest Bathonian to Late Callovian time interval. The oxygen isotopic records from other European regions indicate a similar pattern of long-term palaeotemperature evolution. The comparatively high water temperatures during the Callovian to Oxfordian of the Isle of Skye (NW Scotland) are enigmatic, however. In the Early Oxfordian, sea surface and bottom temperatures began to rise in continental Europe and England. These changes coincide with a south-westward drift of the West European crustal plate, but a causal relationship remains to be demonstrated.