Late Hauterivian-early Barremian Research Articles

Lower Cretaceous holostratigraphy in Svalbard: the Arctic key piece of the Boreal basin puzzle

Abstract Lower Cretaceous stratigraphy of the high palaeo-latitude Arctic-Boreal Realm is generally more poorly understood than its lower-latitude Tethyan counterpart, prohibiting regional correlations and evaluation of global climate dynamics during this important high- p CO 2 period. In this paper, a holostratigraphic scheme and lithostratigraphic revision are presented for the Valanginian–lower Barremian, siliciclastic ramp succession of the Rurikfjellet Formation in Svalbard, drawn from synthesis of the latest published sedimentological, biostratigraphic, petrophysical, sequence stratigraphic, chemostratigraphic and chronostratigraphic results, supplemented by new measured sections from five localities. The offshore mudstone-dominated Wimanfjellet Member (Valanginian–lower Barremian) is retained, whereas three new members are defined according to their distinct geographical, sedimentological and stratigraphic characteristics. The Adventpynten Member (upper(?) Valanginian–lowermost upper Hauterivian) constitutes a thick, relatively localized succession of mass-transport deposits. The Kikutodden Member (Hauterivian–lower Barremian) is discarded and replaced by the northern Bohemanneset Member and southern Fotografryggen Member, representing respectively: heterogeneous prodelta to delta front deposits; and sandy offshore transition to shoreface deposits. The Rurikfjellet Formation records Valanginian–earliest late Hauterivian shoreline progradation followed by late Hauterivian–early Barremian shoreline retreat and flooding across a low-gradient ramp, which never experienced full regression into continental deposits within the extent of the present-day outcrop belt.

Increasing the theropod record of Europe: a new basal spinosaurid from the Enciso Group of the Cameros Basin (La Rioja, Spain). Evolutionary implications and palaeobiodiversity

Abstract A new member of Spinosauridae from the Enciso Group (uppermost Barremian–lower Aptian) from Igea (La Rioja, Spain) is here erected on the basis of axial, pelvic girdle, and hindlimb elements that exhibit a unique combination of characters. Riojavenatrix lacustris gen. et sp. nov. is one of the latest Iberian and European spinosaurid taxa. It retains a triangular pubic boot, like the megalosaurids, and a medial condyle of the femur that shows a transitional stage between the anteroposteriorly oriented long axis of non-spinosaurid theropods and the posteromedially oriented long axis of Spinosauridae. The spinosaurid record of Iberia ranges from the late Hauterivian–early Barremian to the latest Barremian–early Aptian so far, and both the oldest and the most recent evidence comes from the Cameros Basin, where spinosaurid remains are especially abundant in the Barremian deposits. A review of the spinosaurid record has allowed us to dismiss the presence of the genus Baryonyx from Iberia; hence, only Camarillasaurus, Iberospinus, Protathlitis, Riojavenatrix gen. nov., and Vallibonavenatrix are considered to be present in the Early Cretaceous of Iberia. According to this study, Riojavenatrix is one of the youngest baryonychines in the fossil record.

Ornithopod tracks and bones: Paleoecology and an unusual evidence of quadrupedal locomotion in the Lower Cretaceous of eastern Iberia (Teruel, Spain)

Dinosaur tracks and osteological remains in the El Castellar Formation (upper Hauterivian–lower Barremian) in the Peñagolosa subbasin, southwest sector of the Maestrazgo Basin (Teruel Province, Spain), are scarce and fragmentary, respectively. Here, we report several unexpected, well-defined natural casts of large ornithopods from several sites of the El Castellar Formation. Moreover, an unusual manus-pes track set preserved as convex hyporelief has been found in the lowermost sandstone level of the Camarillas Formation, the first evidence of dinosaur for the base of this unit at the Peñagolosa subbasin. The ichnological comparison allows us to ascribe the studied tracks to Caririchnium. Their trackmakers were large styracosternans related to Iguanodon, and the presence of a manus-pes track set verifies that some of them may have a quadrupedal locomotion. This associated manus-pes track set constitutes one of the oldest ichnological pieces of evidence of quadrupedalism in large ornithopods from the Lower Cretaceous of Iberia and increases the limited record of this kind of track in the Lower Cretaceous of Europe. In addition, we describe some osteological fossils of these dinosaurs from the El Castellar Formation. These skeletal remains are related to medium to large-sized styracosternans, some of which closely resemble those of other European styracosternans such as Iguanodon. The evidence provided here verifies that these dinosaurs were frequent components in the coastal wetland, and fluvial to deltaic systems developed, during the late Hauterivian–early Barremian, in the Peñagolosa subbasin, possibly because these may have had a source of fresh vegetation and may have provided protection.

The Aptian-Cenomanian ostracod "Conchoecia?"/Neorichterina: Taxonomic review and its paleoecological, paleobiogeographic, and biostratigraphic significance

Though primarily a recent genus, Conchoecia Dana 1853 has had a number of Cretaceous forms dubiously attributed to it since the description of Conchoecia cretaceaPokorný, 1964. Recently, most of these species were reassigned to the genus NeorichterinaTóth and Cséfán, 2018, considered a Cretaceous representative of Family Entomozoidae. However, there are still taxonomic uncertainties regarding this assignment, and much is still unknown about the paleoecology, paleobiogeography, and biostratigraphic significance of these taxa. This paper provides a revision of the taxon based on available literature on Neorichterina and the Cretaceous forms attributed to “Conchoecia”. Considering several problems with the taxonomic description of Neorichterina, we propose the removal of the genus from Family Entomozoidae, and identify two potential new species, which are left in open nomenclature. The earliest occurrence of the genus is the late Hauterivian–early Barremian of the Haha Basin, Morocco. After that, Neorichterina spread to the South Atlantic and Tethys oceans during the late Aptian–late Albian, and became extinct in the lower Cenomanian. Neorichterina was likely a planktonic genus with a preference for warm neritic environments, and was able to tolerate fluctuating oxygenation levels. It frequently occurred in association with blooms of Favusellid foraminifera, and was particularly abundant in the South Atlantic Ocean. Although Neorichterina has a broad stratigraphic range, it occurred only for a small time interval during the late Aptian of the Santos Basin, Brazil, suggesting that it could be a useful regional biostratigraphic marker in the southeastern Brazilian margin.

The late Berriasian early evolutionary burst of the Orbitolinidae: New insights into taxonomy, origin, diversification and phylogeny of the family based on data from eastern Serbia

New data from the Carpatho-Balkanides of eastern Serbia evidence the more or less near-simultaneous "explosive" first appearances of several genera of the Orbitolinidae in the late Berriasian. Most of the observed taxa were previously recorded from strata not older than the Late Hauterivian (= classical Urgonian of southeastern France), evidence that these ages refer to local first appearance data. The diversified assemblage from Serbia includes representatives of the subfamilies Dictyoconinae: genera Cribellopsis ARNAUD-VANNEAU, Montseciella CHERCHI & SCHROEDER, Orbitolinopsis HENSON, Urgonina FOURY & MOULLADE, Valserina SCHROEDER & CONRAD, Vanneauina SCHLAGINTWEIT, and Dictyorbitolininae: genus Paracoskinolina MOULLADE. Representatives of the Orbitolininae (with complex embryo) have not been observed. They appeared later in the fossil record seemingly during the Late Hauterivian-early Barremian. All together 17 taxa are reported, of which three in open nomenclature. A new species is described as Cribellopsis sudari n. sp. The majority of the observed species display medium- to high-conical tests and a rather simple exoskeleton lacking horizontal partitions (rafters). The new data contradict a phylogenetic evolution of distinct genera displaying different internal test structures one after the other in time (= ancestor-descendant relationships) as postulated by some authors. The explosive radiation ("early burst") of the Orbitolinidae in the late Berriasian is accompanied by the first appearance date of several other large benthic foraminifera including mostly agglutinating (e.g., Ammocycloloculina, Choffatella, Drevennia, Eclusia, Moulladella, Pfenderina, Pseudotextulariella) but also complex porcelaneous taxa (Pavlovcevina) providing evidence for a bioevent in this time period that exceeds the number of taxa originating in the previous (Tithonian) and the following stage (Valanginian). The early evolutionary history of the Orbitolinidae can be considered a classical example of adaptive radiation within the clade's history.

Sequence stratigraphy and distribution of organic-rich Lower Cretaceous mixed clastic-carbonate strata in Matruh Basin, northwestern Egypt: Constrains on the Tethyan sea level changes, palaeoclimate, and tectonics

Integrated palynological, lithological, and geophysical analyses of the Lower Cretaceous (upper Hauterivian-Aptian) in Matruh Basin enabled conducting a high-resolution sequence stratigraphic analysis. Fluctuations of the continental/marine palynomorphs ratio reflect changes in the Tethyan 3rd order sea levels and are mirrored by eminent vertical changes in the spontaneous potential and the lithofacies. These are used with abundance of the marine phytoplanktons and opaque/translucent phytoclasts ratio to identify three 3rd order (SQ1: 132.4–120.8 Ma, SQ2: 120.8–115.2 Ma, and SQ3: 115.2–113 Ma) and seven 4th order genetic sequences and to study the impact of the allogenic and autogenic processes on their deposition.Deposition of the deltaic clastic systems tracts of the lower-middle Alam El Bueib (late Hauterivian-early Barremian) and Dahab (late Aptian) formations reflect the interaction between the regional humid climate and the Tethyan 3rd order sea levels, which superimposed the Tethyan 2nd order sea level. Interferences of minor regional tectonics were also important. The argillaceous deposits possess large amounts of terrestrial organic matter of low hydrogen index (HI: 185.8–211.5 mg HC/g TOC) indicating gas organic facies. These deposits show relatively high organic richness (1.81–2.50 TOC wt %) due to relatively low sediment dilution and water circulation (i.e. suboxic-anoxic conditions) and high primary productivity due to high riverine nutrient inputs.Deposition of the inner-middle shelf clastic-carbonate systems tracts of the upper Alam El Bueib and Alamein formations (latest Barremian-middle Aptian) reflects the interaction between the climatically induced low terrigenous influx and carbonate sedimentation due to shift to relatively dry climate, changes in the Tethyan 3rd order sea levels, and the middle Aptian regional minor uplift. These systems tracts show relatively large amounts of terrestrial organic matter, a notable marine organic matter signature, and intermediate HI (283.1–239.0 mg HC/g TOC) indicating gas/oil organic facies. The shales and siltstones are relatively organic richer (1.88–2.28 TOC wt %) than the pure and the argillaceous dolostones (1.46–1.94 TOC wt %). This organic richness is related to combined low sedimentation rates, low water circulation (i.e. dysoxic-suboxic to suboxic-anoxic conditions), and relatively high primary productivity.Overall, the Tethyan sea level changes, regional climate, and regional tectonics played a major role in the deposition of the organic-rich syn-rift Lower Cretaceous deposits in Matruh Basin.

Composition of Lower Cretaceous mudstones of the Algarve Basin and implications for Iberian palaeoclimates

Several compositional features of mudstones are controlled by climate-driven weathering and have been used to approximate palaeoclimatic conditions. Mudstone composition, however, is also influenced by the geology of the source areas and diverse depositional and post-depositional processes. The present geochemical and mineralogical study of the Lower Cretaceous (upper Hauterivian to Aptian) of the Algarve Basin (Southern Portugal) was performed to investigate the main factors that control mudstone composition and extract possible climatic signals. Clay mineralogy partially reflects diverse contributions of felsic vs. mafic and recycled materials, and the geochemical weathering proxies applied to the detrital component of mudstones are differently affected by provenance and hydraulic fractionation. Despite these facts, a wide set of compositional data allows some robust climatic interpretations. Apart from the early Aptian (Burgau Formation), when climate was probably wetter, hot and dry conditions prevailed in south Iberia during the investigated interval, with minimum humidity during the late Hauterivian–early Barremian (Salema Formation). Independent sedimentological and palaeontogical data support these interpretations. A comparison with compositional results for the Lusitanian Basin reveals substantially drier climates in southern than central and northern Iberia. Interpreted patterns of climatic evolution can be linked to shifts in air circulation from the sub-tropical high-pressure belt.

REVIEW OF MICROFOSSIL-BEARING CLASTS WITHIN LATE MESOZOIC STRATA IN EAST ASIA: STAGED DENUDATION OF MID-MESOZOIC ACCRETIONARY COMPLEXES

Late Mesozoic neritic-continental strata of East Asia show intercalations of conglomerates including microfossil-bearing clasts. Some clasts are presumed to have originated in mid-Mesozoic accretionary complexes (ACs) of East Asia. Microfossils ( e.g ., radiolaria, conodonts) in these clasts can provide age constraints. Relationships between rock facies and age in sequences of the mid-Mesozoic ACs have been clarified in previous studies; therefore, the rock facies and the age of the clasts offer a clue about denudation history and provenance of the mid-Mesozoic ACs. This study compiles previous studies of microfossil-bearing clasts within the Late Mesozoic in the Outer and Inner Zone of Southwest Japan and in the Gyeongsang Supergroup in the southeastern Korean Peninsula. The compilation, at present, recognizes three denudation stages (Stages A, B, and C) of the mid-Mesozoic accretionary complexes. Stage A (Oxfordian-Hauterivian) is characterized by an initial and narrow denudation. The denudation of the mid-Mesozoic ACs started at some point in this stage, but it was of limited extent. Stage B (Barremian-early Albian) is characterized by wide denudation: the mid-Mesozoic ACs became largely exposed. Afterwards, some younger geologic bodies of the mid-Mesozoic ACs, which were structurally underlying, were exposed and denuded. Stage C (late Albian–) is characterized by denudation of almost all the mid-Mesozoic accretionary complexes. This denudational evolution might be related to some tectonic and igneous events in East Asia, such as the uplift of the Tetori Group in late Hauterivian-early Barremian and the initiation of the granitic magmatic activity in middle Albian.

On the diversity of Iberian iguanodont dinosaurs: New fossils from the lower Barremian, Teruel province, Spain

New fossils from the lower Barremian (Lower Cretaceous) of Spain increase the known occurrence of iguanodont dinosaurs (i.e. members of the clade Iguanodontia) in the Iberian Peninsula. A partial dentary and ischium from the fossil locality of La Cantalera 2 (Blesa Formation, municipality of Josa, Teruel province) testify to the presence of a new specimen in the early Barremian of Iberia, closely related to Delapparentia turolensis, which was previously only known in the type locality (La Maca-3, Camarillas Formation, municipality of Galve, Teruel province). These new fossils are assigned to Delapparentia turolensis (ischium) and cf. Delapparentia sp. (dentary). Moreover, the description and comparison of some of the characters of the ischium reveal that this bone is of previously unnoticed relevance for iguanodont systematics. The differences in overlapping postcranial material – observed by comparing ischial material from the provinces of Teruel and Burgos – lead us to conclude that late Hauterivian-early Barremian iguanodont diversity in Iberia consists of at least two different taxa: Delapparentia turolensis and another form closely related to Iguanodon. Additionally, dental morphotypes from La Cantalera bonebed evince the presence of at least three different iguanodonts in the lower Barremian of Iberia.

Late Hauterivian–early Barremian calcareous nannofossil biostratigraphy, palaeoceanography, and stable isotope record in the Subbetic domain (southern Spain)

Two sections in the Subbetic domain of the Betic Cordillera (Río Argos and Arroyo Gilico), encompassing the latest Hauterivian–earliest late Barremian interval, and including the Faraoni level equivalent (FLE) and the ‘Mid-Barremian event’ (MBE), were selected for stable isotope analyses and calcareous nannofossil investigation. Six calcareous nannofossil bioevents were identified throughout the study interval, which were used in the identification of NC5B, NC5C, NC5D and NC5E subzones. Calcareous nannofossil bioevents and subzones have been directly correlated to Tethyan ammonite biostratigraphical zonation and with respect to a detailed carbon and oxygen stable isotope stratigraphy. An integrated analysis of calcareous nannofossil assemblages and chemostratigraphic data (carbon and oxygen isotopes) enabled the reconstruction of the surface water conditions throughout the study interval. Calcareous nannofossil assemblages record several episodes of relative eutrophication of surface water that correlate with relative minimum values in the stable oxygen isotope curves. These eutrophication episodes are interpreted as the result of probably warmer and wetter climatic conditions in the continental hinterlands adjacent to the Subbetic Basin, which led to an enhanced runoff and increased freshwater input to the sea. During these episodes, surface waters were enriched in nutrients and probably had a lower salinity, favouring the development of a high nutricline and, occasionally, water stratification and development of localized dysoxic/anoxic bottom sedimentary environments. Most of these episodes are of minor importance, and only two of them (those correlating with FLE and MBE), had sufficient impact on the marine environments to generate deviations in the stable carbon isotope record and localized deposition of organic-rich sediments. This suggests that global dysoxic/anoxic episodes, such as those linked to OAEs, probably do not represent singular events in a normally undisturbed environment, but are part of long-lasting periods of environmental change.

Heteroporella ? paucicalcarea (CONRAD, 1970), an Urgonian Dasycladalean alga revisited

When the species Heteroporella ? paucicalcarea (Conrad, 1970) was erected it was left in open nomenclature. Later on new combinations were introduced but did not meet a general agreement among paleophycologists. Considering the current acception of the Dasycladalean families, we ascribe it to the Family Polyphysaceae and subsequently to the genus Clypeina (Michelin, 1845). Its known stratigraphic range is rather brief (Late Hauterivian-Early Barremian), which makes it a good index fossil in Urgonian carbonate platform series. Its geographical distribution is apparently restricted to Western Europe (France, Spain and Switzerland).

Larachelus morla, gen. et sp. nov., a new member of the little-known European Early Cretaceous record of stem cryptodiran turtles

ABSTRACT A relatively diverse record of European Early Cretaceous pan-cryptodiran turtles has been revealed from the analysis of new specimens and from a review of previously defined taxa. However, knowledge about many of these taxa remains relatively limited. We erect the new taxon, Larachelus morla, gen. et sp. nov., on the basis of a shell from the late Hauterivian–early Barremian of the Iberian Range (Spain). The comparative study of this taxon with the continental European Cretaceous pan-cryptodiran representatives and cladistic analyses reveal L. morla to be a member of the little-known European Early Cretaceous stem Cryptodira. Stem cryptodirans have been recognized from the Early Cretaceous of several continents. The study of L. morla not only confirms the presence of this group in the Early Cretaceous of Europe, it also provides new insights into the European evolution of Pan-Cryptodira. This finding reveals greater diversity in European Early Cretaceous continental pan-cryptodires, highlighting its Hauterivian–Aptian record. This diversity is particularly relevant in the Iberian Range, where several clades of turtles whose coexistence has not been recognized in the Lower Cretaceous of any other region are identified: paracryptodiran members, stem cryptodiran turtles, and representatives of several lineages of the crown group Cryptodira. This very high diversity of continental taxa shows a wide range of morphological diversity that could be related to adaptation to different ecological niches.

A systematic reassessment of Early Cretaceous multituberculates from Galve (Teruel, Spain)

This paper includes a systematic reassessment of the Early Cretaceous (late Hauterivian–early Barremian) multituberculate fossils of Galve (Teruel, Spain), previously studied by Crusafont-Pairó and Adrover, and Crusafont-Pairó and Gibert in 1966 and 1976, respectively, as well the study of other unpublished specimens found in the revised collection of Institut Català de Paleontologia (ICP). We here include for the first time the emended descriptions and comparisons as well as the SEM photographs of all the specimens found in the collection and update the biostratigraphic data that they have provided. The multituberculate fossil assemblage from Galve comprises at least four taxa: the paulchoffatiid Galveodon nannothus, the eobaatarid Eobaatar hispanicus, another eobaatarid or a possible plagiaulacid, Iberica hahni gen. et sp. nov., and the pinheirodontid Lavocatia alfambrensis. The species Parendotherium herreroi has been removed from the multituberculate faunal list of Galve. Another two different taxa, provisionally classified as Paulchoffatiidae indet. and Plagiaulacidae or Eobaataridae indet. could be added to the list if their validity can be assessed once more specimen are found. The presence of more than four different “plagiaulacidan” multituberculate taxa in the late Hauterivian–early Barremian of the Galve area suggests a high biodiversity of these mammal faunas in the Early Cretaceous age of the Iberian Peninsula.

A new purported ankylosaur trackway in the Lower Cretaceous (lower Aptian) shallow-marine carbonate deposits of Puglia, southern Italy

The Apulian marine carbonate Platform, an unusual environment for terrestrial animals, has revealed a diverse ichnological record, especially for dinosaurs. Members of most higher taxa are present, including sauropods, theropods, ankylosaurs and ornithopods. Recently, a small outcrop of Aptian age referred to the Calcare di Bari near Bisceglie (Bari) has yielded a new quadrupedal trackway that we attribute to Ankylosauria. This new find enhances the record of Cretaceous ankylosaur footprints from the Apulian carbonate Platform, previously known from another site near Bisceglie (early Aptian), from Borgo Celano (late Hauterivian–early Barremian), and from Altamura (late Coniacian–early Santonian).

A concealed Lower Cretaceous outlier at Moss of Cruden, Grampian Region

Synopsis Recent excavations at Moss of Cruden, Grampian Region, show that Lower Cretaceous sedimentary rocks pass beneath the margin of the Tertiary Buchan Ridge Gravels and are intensely weathered. These findings indicate that previous interpretations of these rocks as a glacially-transported erratic mass or masses were incorrect and that they are probably in situ. The rocks include fine-grained, glauconitic quartz-arenites with pollen of Late Hauterivian-early Barremian age. Overlying flint gravels demonstrate the presence of a former Cretaceous chalk cover and helped the preservation of this small outlier.