Search

A review of short-term (

The Mesozoic era (∼252 to 66 million years ago) was a key interval in Earth's evolution toward its modern state, witnessing the breakup of the supercontinent Pangaea and significant biotic innovations like the early evolution of mammals. Plate tectonic dynamics drove a fundamental climatic transition from the early Mesozoic supercontinent toward the Late Cretaceous fragmented continental configuration. Here, key aspects of Mesozoic long‐term environmental changes are assessed in a climate model ensemble framework. We analyze so far the most extended ensemble of equilibrium climate states simulated for evolving Mesozoic boundary conditions covering the period from 255 to 60 Ma in 5 Myr timesteps. Global mean temperatures are generally found to be elevated above the present and exhibit a baseline warming trend driven by rising sea levels and increasing solar luminosity. Warm (Triassic and mid‐Cretaceous) and cool (Jurassic and end‐Cretaceous) anomalies result from pCO2 changes indicated by different reconstructions. Seasonal and zonal temperature contrasts as well as continental aridity show an overall decrease from the Late Triassic‐Early Jurassic to the Late Cretaceous. Meridional temperature gradients are reduced at higher global temperatures and less land area in the high latitudes. With systematic sensitivity experiments, the influence of paleogeography, sea level, vegetation patterns, pCO2, solar luminosity, and orbital configuration on these trends is investigated. For example, long‐term seasonality trends are driven by paleogeography, but orbital cycles could have had similar‐scale effects on shorter timescales. Global mean temperatures, continental humidity, and meridional temperature gradients are, however, also strongly affected by pCO2., Key Points We assess global long‐term climate trends through the Mesozoic era with an ensemble of climate model simulationsVarying carbon dioxide levels cause anomalies around an overall warming trend due to changing paleogeography and increasing insolationSeasonal and zonal temperature contrasts as well as aridity decrease with time, while meridional gradients vary with paleogeography

The Luanping Basin of northern Hebei, North China, is well known for its continuous nonmarine Lower Cretaceous deposits and the preservation of the Jehol Biota. However, there are still some controversies about the stratigraphic correlation in these regions. Here we report some advances on the study of the nonmarine ostracods of Luanping, focusing on its biostratigraphical utility. Preliminary results indicate that the nonmarine ostracods from Luanping Basin consist of 17 genera and around 44 species. The ostracod assemblages of the Dabeigou, Dadianzi and Xiguayuan formations of this Basin can be assigned to the Luanpingella-Ocrocypris-Eoparacypris (Late Valanginian-Early Hauterivian age), Cypridea-Timiriasevia-Daurina (Late Huaterivian-Barremian age) and Cypridea-Limnocypridea-Lycopterocypris (Aptian stage) zones, respectively. This temporary framework can be served as a stratigraphic correlation tool in northern Hebei, as well as contributed to a better understanding of the evolution of the Jehol Biota.

The Upper Cretaceous Postalm section in the Northern Calcareous Alps (Austria) exposes pelagic deposits of the northwestern Tethys whose cyclostratigraphy and palaeoenvironments were examined in this study. The section displays rhythmic deposits of Santonian to late Campanian age (Gosau Group). The Santonian/Campanian transition is characterised by condensed greyish carbonates, while the younger deposits are composed of reddish foraminiferal packstones displaying distinct limestone-marl alternations. A biostratigraphic framework based on planktonic foraminifera and calcareous nannofossils is supported by carbon and strontium isotope stratigraphy as well as magnetostratigraphy. The carbon isotope data allow to correlate the Postalm section to other Tethyan reference sites and to identify δ13C events, such as the Late Campanian Event. Spectral analyses of three independently assessed proxies (δ13C, Fe content and the thickness of limestone/marl couplets) in the upper, continuously exposed section part identified 17 to 18 405 ka cycles spanning the mid to upper Campanian (Contusotruncana plummerae to Gansserina gansseri Zones or CC21/UC15c to CC23a/UC16 nannofossil zones).

The Turonian–Coniacian continental fossil record in Europe is scarce. Here we present a new fossil assemblage of early Coniacian age that was systematically collected from the coal-bearing Gosau Group of the Tiefengraben locality near St. Wolfgang, Austria. The diverse assemblage is composed of at least 60 taxa including sporomorphs and Normapolles-related pollen, seeds and leaves of angiosperms and gymnosperms, charophytes, gastropods, bivalves, ostracods, termites, fishes, crocodiles and dinosaurs. Concerning charophytes, ostracods, gastropods, crocodiles and dinosaurs, the discovered specimens either extend the temporal and spatial range of specific groups (in some cases as possible relict forms) or suggest the occurrence of new taxa. The discovered remains of algae, molluscs, ostracods, calcareous nannofossils and lepisosteid fish represent a mixed faunal assemblage from different palaeohabitats, from marginal marine to low salinity and freshwater or terrestrial environments. As Normapolles-related angiosperm plants dominate the flora with a relatively high number of dentate leaves, a slightly cooler microenvironment compared to other Turonian–Coniacian Central European localities is indicated. The characteristically grooved crocodylian teeth of Tiefengraben differ from the previously known Upper Cretaceous European crocodyliform teeth and suggest a more diverse crocodyliform fauna in the region. Dinosaurs are represented by teeth of at least three different theropods, the largest of which is referred here to as basal tetanurans. The fossil assemblage of this early Gosau Group occurrence is of great importance for our understanding of the continental floristic and faunistic composition of the western Tethyan archipelago during the Cenomanian–Campanian gap.

Burmese Cretaceous amber (∼99 Ma, Myanmar) is famous for the preservation of a wide range of fauna and flora, including representatives of marine, freshwater and terrestrial groups. Here, we report on three ostracod specimens, that came visible as syninclusions to an aquatic isopod. The three specimens represent three different taxa, that were found preserved in a single piece of amber. One of the described specimens was studied using µCT scanning data. On the basis of general carapace morphology we assign all three to the group Podocopida, and (tentatively) its ingroup Cypridocopina. A lack of visibility of more particular diagnostic features such as adductor muscle scars and details of the marginal zone precludes a further identification, but we discuss possible affinities with either the marine-brackish group Pontocypridoidea or the non-marine group Cypridoidea. The taphonomy indicates that the studied ostracods had been subject to limited (if any) post-mortem transport, which could be consistent with marginal marine environments.

The Dabeigou Formation in the Luanping basin in northern China is well known for its continuous non-marine Lower Cretaceous deposits and the preservation of the early Jehol Biota, including abundant ostracods. However, the age of the Dabeigou Formation is still disputed. Here, we present a detailed lithostratigraphic analysis and ostracod biostratigraphy of the newly exposed Yushuxia section of the Luanping basin. At this locality, the Dabeigou Formation can be subdivided into 46 layers, which is mainly composed of grey to dark grey fine clastics of semi-deep lake face. Ostracod analysis on samples from the Dabeigou Formation revealed 14 species of nine genera. Biostratigraphically, the ostracods of the Dabeigou Formation belong to the Luanpingella-Torinina-Eoparacypris Zone. Most of the species range from the latest Jurassic to the earliest Cretaceous. However, some species show a closer relation with ostracods from the upper Lower Cretaceous Dadianzi Formation (upper Hauterivian to Barremian), the Yixian Formation (lower Aptian) of North China, and the Purbeck–Wealden Group (uppermost Tithonian to lowermost Aptian) of Britain. Combined with the biostratigraphy of other fossils and the U-Pb age, it is suggested that the ostracod fauna of the Dabeigou Formation and the origin of early Jehol Biota might be of Early Cretaceous age entirely.

Micropalaeontological investigations of the Bouhedma Formation in the Jebel Majoura section from the southern Central Tunisian Atlas revealed four successive ostracod associations (in total 16 species of 13 genera) of higher palaeoenvironmental, and thus far limited biostratigraphic and palaeobiogeographic utility due to poor preservation. The most notable of these is a new upper Hauterivian?–Barremian non-marine Wealden-type ostracod assemblage of high diversity from the Lower Member of the Bouhedma Formation, the first one documented from the southern Central Tunisian Atlas, which consists of 9 species: Cypridea cyrtorostralis, Cypridea aff. tenuis, Cypridea aff. insulae, Cypridea sp., Theriosynoecum cf. fittoni, Vecticypris polita, Alicenula? leguminella, as well as Klieana sp. and Fabanella sp. The subsequent two ostracod assemblages from the Lower Member are characterized by the brackish species Rehacythereis? sp., Fabanella sp., Ilyocypris sp., and Schuleridea? sp. indicating transition to lagoonal environment. The subsequent ostracod assemblage from two levels of the Middle Member of the Bouhedma Formation is exclusively composed of the euryhaline marginal marine Paracypris sp., and the marine species Antepaijenborchella praealta, Protocythere cf. bedoulensis and Metacytheropteron aff. grosdidieri, reflecting a marine incursion event. The biostratigraphic utility, particularly that based on the non-marine fauna, is limited thus far but the results are consistent with an upper Hauterivian?–Barremian age previously assigned to the Bouhedma Formation from the southern Central Tunisian Atlas, facilitating its regional stratigraphic correlation with coeval series from the northern part of this palaeogeographic domain. The discovery of Tunisian Wealden-type non-marine ostracods from the southwestern margin of the Tethys (North Africa) sheds new light on the dispersal patterns and palaeobiogeography of these ostracods, their potential utility as biostratigraphic tool, as well as on the significance of the north Gondwanan continental basins and peri-Tethyan islands of the Central Tunisian Atlas for recording Early Cretaceous non-marine microfaunas and -floras.

The Jehol Biota of northern China provides a new and unmatched window for the reconstruction and understanding of Early Cretaceous terrestrial ecosystems. Previous studies on the paleoenvironmental and paleoclimatic background of the Jehol Biota have mainly focused on middle–late evolutionary stages while the less diverse and more narrowly distributed early Jehol Biota remains less understood. The Lower Cretaceous (Valanginian–Hauterivian) Dabeigou Formation in the Luanping Basin (North China), preserves the early stage of the Jehol Biota and can be subdivided into three members. To reconstruct the living environment of the early Jehol Biota, we explored the geochemistry, bulk mineralogy, total organic carbon, sedimentology, and paleoecology of the Dabeigou Formation from the Yushuxia section of the Luanping Basin. Decreased volcanic activity during the deposition of the Dabeigou Formation resulted in changes in its source material from felsic to mafic. The Luanping palaeolake reached its deepest water depth during deposition of the Member 2, and generally exhibited low salinity, while a short time of high salinity occurred during deposition of the Member 3. Analysis on the paleoweathering indices and other evidences, indicate that the Luanping area was generally in cold and humid climate conditions during deposition of the members 1 and 2 (correlated to the Weissert Event), but changed to warm climate conditions during deposition of the Member 3, which coincides with an increasing trend of biotic diversity. Consequently, our results suggest that the increasingly warm paleoclimate and lacustrine productivity, associated with decreasingly volcanic activity in North China, have contributed to the early evolution of the Jehol Biota.

Non-marine strata of Lower Cretaceous age in western Liaoning and northern Hebei, North China, are famous for its Jehol Biota, including abundant ostracods. However, there are still some controversies about the stratigraphic correlation in these regions, for instance, it is still debated whether the interval from the Liying section of Luanping Basin belongs to the Dadianzi Formation or the member 1 of the Xiguayuan Formation. Ostracods act as an important tool for the correlation of the stratigraphy within or between basins. Here we report and illustrate the ostracods from the Liying section in detail for the first time, and aim to determine the section's stratigraphic correlation. Results show that, the Liying section has a thickness of 157.65 m and can be divided into 33 layers. Ostracods from this section are mainly distributed in the lower and middle part, and 7 genera and 13 species have been preliminarily recognized. These ostracod species can be summarized as the Cypridea-Limnocypridea-Lycopterocypris Assemblage Zone temporarily. Based on the identified ostracods, occurrence of other abundant representative fossils of the Jehol Biota, and isotope dating results, the major interval of the Liying section should be assigned to member 1 of the Xiguayuan Formation, and can be correlated with the Yixian Formation from western Liaoning.

This work provides the first detailed taxonomic study of ostracod species from the Shenjiatun section (Nenjiang Formation, Songliao Basin, northeast China). Ten species belonging to seven genera are recognized. At the species level, this ostracod fauna shows a high degree of endemicity. The ontogeny of two species is recognized in this study, and sexual dimorphism within Daqingella arca is unequivocally recognized for the first time. The ostracod fauna suggests that this fossil-bearing sedimentary succession should be assigned to members 3–4 (Campanian) of the Nenjiang Formation (mainly Member 3) instead of representing ‘Quaternary sediments’ as previously thought. On the basis of the ostracod fauna, Member 3 of the Nenjiang Formation at Shenjiatun represents a shallow-littoral, lacustrine depositional environment that, at least in the upper part of Member 3, potentially included less stable conditions characterized by smaller, ephemeral waterbodies and increased (non-marine, oligohaline) salinities through evaporation.

Non-marine ostracods have been used for a long time to aid in the understanding of the Lower Cretaceous sedimentary deposits of Brazil, with various studies showing their value for biostratigraphic zonation in different basins. The northeastern region of Brazil contains several basins south of the Potiguar Basin which originated from the rifting that resulted from the opening of the Atlantic Ocean, and thus contain an important record of the Cretaceous Period. This paper has the objective of studying the ostracods recovered from two adjacent sections (Transnordestina A and Transnordestina B) belonging to the Oros Formation, Iguatu Basin, Ceara, Brazil, detailing their taxonomy and developing biostratigraphic inferences based on the observed fauna. A total of 19 species were found in the analyzed samples, distributed among 11 genera and five families: Cypridea hystricoides, Cypridea paraibensis, Cypridea cf. C. clavata, Cypridea punctacentralis sp. nov., Brasacypris ovum, Pattersoncypris sinuata, Pattersoncypris cf. P. sinuata, Pattersoncypris? sp., Ilyocypris? arca sp. nov., Ilyocypris? latanodi sp. nov., Rhinocypris? ericius sp. nov., Pythagoracypris latavectis gen. et sp. nov., Hastacypris adamantem gen. et sp. nov., Looneyellopsis mvili, Musacchiocythere plastica, Musacchiocythere? sp., Alicenula leguminella, Alicenula cf. D. oblonga, and an incertae sedis species. From the recovered species, a Hauterivian–Aptian interval can be inferred for the studied sections.

Two non-marine to marginal-marine intervals have been identified by ostracod assemblages in the mid-Cretaceous carbonate platform of the Central Tunisian Atlas, the deposits of which belong to the Orbata Formation. The first non-marine interval has been recorded within member Unit 2b of the Orbata Formation which yielded the first lower Aptian ostracod fauna composed of Alicenula? leguminella, Vecticypris polita, Cypridea ventriosa, Perissocytheridea altesulcata sp. nov., Harbinia? cf. sinuata, Hourcqia aff. bateke, Ovocytheridea nuda, Bythocypris? pythagorasi sp. nov., Paracypris lusitanicus and Paracypris chekhmai sp. nov. The assemblages indicate continental to marginal-coastal environment and lower Aptian emergence of the Orbata Platform, and are interpreted as response to an earliest Aptian 3rd-order (0.5–3 myr) sea-level fall event of major amplitude. A second lowermost Albian ostracod fauna, recorded within members Unit 5b, 6 of the Orbata Formation, is composed of Candonopsis carthaginensis sp. nov., Cypridea quadrangulata, Virgatocypris kechoulaensis, Alicenula? leguminella, Vecticypris polita, Stenestroemia mosensis, Perissocytheridea kouminiensis sp. nov., Hourcqia aff. bateke, Dolocytheridea bosquetiana, Dolocytheridea donzei sp. nov., Ovocytheridea anterocompressa, Paracypris dubertreti, Paracypris mdaouerensis, Clithrocytheridea espichelensis, Bythocypris? multagracilis sp. nov. and Bythocypris dorsogibba sp. nov. The assemblages indicate another interval of non-marine to marginal-marine depositional settings as direct response to a prominent eustatic latest Aptian to earliest Albian sea-level fall event that enhanced the quasi-total emersion of the Central Tunisian Atlas palaeogeographic domain. Hence, the two studied faunas herein allow us to define two stratigraphic key surfaces of regional utility giving new insights into the chronostratigrahic subdivision of the Orbata carbonate platform, especially in supporting a previously neglected early Albian age of its upper part (Unit 5b, 6 and 7) and allow the regional stratigraphic correlation of these key surfaces in the Central Tunisian Atlas (CTA) domain. Accordingly, our results not only disprove the previous consideration of an uppermost Aptian–lower Albian hiatus but also implicate the necessity to redefine and review the previous palaeogeographic and tectono-sedimentary schemes of the CTA as suggested for almost fourty years.

The base of the Campanian still lacks a designated primary marker and a defined GSSP (Global Boundary Stratotype Section and Point). We present a Santonian–Campanian boundary section from the Postalm in the Northern Calcareous Alps of Austria as a possible reference section for the northwestern Tethys. Including nearby complementary Gosau Group sections, the stratigraphy for this time interval is based on palaeomagnetic and stable isotope data, planktonic foraminifera and calcareous nannoplankton bio-stratigraphy, and strontium isotope stratigraphy, together with published ammonite, crinoid and inoceramid data. The Postalm section shows a deepening trend from upper Santonian conglomerates and grey shelf marls to pelagic bathyal red marly limestones of mainly Campanian age. Palaeomagnetic data allow identifying the top of the Long Cretaceous Normal Polarity-Chron C34n and the following reversal in the lower part of the red marly limestones. A 1 m-thick interval of high magnetic susceptibility is present at the end of C34n. Two of the main suggested biomarkers to pinpoint the Santonian–Campanian boundary, i. e. the last occurrence of the planktonic foraminifer Dicarinella asymetrica and the first occurrence of the nannofossil Broinsonia parca parca, occur in close proximity above the reversal, which is suggested herein as the main marker event for the base of the Campanian. Strontium isotope stratigraphy indicates a value of 0.707534 (mean of four measurements at the boundary interval) for the base of the Campanian in the Postalm section. Both carbon and oxygen isotope values show a negative excursion just below the boundary. The positive Santonian–Campanian carbon isotope event starts probably just below the reversal but seems to be diagenetically distorted. This interval is considered to correspond to a short sea-level high in the late Santonian followed by a distinct lowstand at the Santonian–Campanian boundary.

The celebrated fossil locality of Tendaguru (Tanzania, East Africa) has been well known for its unique Late Jurassic dinosaur assemblages since the early decades of the 20th century. Recently, within the scope of the German-Tanzanian Tendaguru project, an expedition returned to Tendaguru with the aim of collecting microvertebrates, micro- and macroinvertebrates, plant fossils and new sedimentological and stratigraphical data. Applying a multidisciplinary research approach, the data collected were used to address various controversial issues regarding the Tendaguru Beds. These include their exact age, depositional environments and reconstructions of the palaeoecosystems in which the dinosaurs lived. Field work resulted in a new standard section for the Tendaguru Beds. Preliminary biostratigraphic results, based on ammonites, charophytes and palynomorphs, support a Late Kimmeridgian age for the Nerinea Bed, an early Tithonian age for the Trigonia smeei Bed, and an Early Cretaceous (possibly Valanginian to Hauterivian) age for the Trigonia schwarzi Bed. Facies analysis of the Tendaguru Beds indicates environments ranging from storm- and tide-influenced, siliciclastic coastal barrier systems, ooid sand bar complexes and backbarrier tidal flats to sabkha-like coastal plains with brackish lakes and pools. Sedimentological indicators of palaeoclimate and palynological data point to a subtropical to tropical climate with pronounced dry seasons. In concert with sedimentological data, quantitative palaeoecological analysis of macroinvertebrates helped to finetune understanding of environmental factors such as substrate conditions, salinity, sedimentation rate and water depth. Along with abundant microvertebrate remains and fragments of fusain and cuticles, these new data have considerably improved our knowledge of the fauna and flora found in the Tendaguru Beds, and provide a solid basis for developing a better understanding of the Late Jurassic and Early Cretaceous Tendaguru palaeoecosystems. To put the German-Tanzanian Tendaguru expedition in perspective, a brief review of previous activities is given and future research objectives are outlined. Die berühmte Fossilfundstätte Tendaguru (Tansania, Ostafrika) ist seit Anfang des 20. Jahrhunderts weltweit für ihre Dinosaurier aus der späten Jura-Zeit bekannt. Im Rahmen des Deutsch-Tansanischen Tendaguru Projekts fand im August und September 2000 eine Expedition in die Umgebung des Tendaguru-Hügels statt. Ziel der Expedition war es, umfangreiche Fossilaufsammlungen von Mikrovertebraten, Mikro- und Makroinvertebraten und pflanzlichen Fossilien durchzuführen und neue sedimentologische und stratigraphische Daten aufzunehmen. Unter Anwendung eines interdisziplinären Forschungsansatzes wurden mit den gesammelten Daten verschiedene, bisher kontrovers diskutierte Aspekte der Tendaguru-Schichten untersucht. Offene Fragen umfassten die genaue Alterseinstufung, eine Interpretation der Ablagerungsräume und die Rekonstruktion der Paläoökosysteme, in denen die Dinosaurier lebten. Die erste Auswertung der Geländedaten führte zu einem neuen Standardprofil für die Tendaguru-Schichten. Vorläufige biostratigraphische Ergebnisse, die auf Ammoniten, Charophyten und Palynomorphen basieren, sprechen für ein Ober-Kimmeridgium Alter der Nerineen Schicht, Unteres Tithonium für die Trigonia smeei Schicht und Untere Kreide (möglicherweise Valanginium bis Hauterivium) für die Trigonia schwarzi Schicht. Die Lebens- und Ablagerungsräume der Tendaguru-Schichten reichten von sturm- und gezeitenbeeinflussten, küstennahen, siliziklastischen Barrieresystemen und Kalkooid-Barren über ausgedehnte Wattflächen bis zu sabkha-artigen Küstenebenen mit brackischen Seen und Tümpeln. Sedimentologische Anzeiger des Paläoklimas und palynologische Daten sprechen für ein subtropisches bis tropisches Klima mit ausgeprägten Trockenzeiten. Im Verbund mit sedimentologischen Daten ermöglicht die quantitative paläoökologische Analyse der Makroinvertebraten eine genauere Charakterisierung wichtiger physikalischer Umweltparameter wie Substrateigenschaften. Salinität. Sedimentationsrate und Bathymetrie. Zusammen mit den häufig vorkommenden Mikrovertebraten und Bruchstücken von Fusit und Cuticulen haben diese neu gewonnenen Daten die Kenntnisse über die Faunen und Floren der Tendaguru-Schichten erheblich erweitert und liefern die Basis für ein besseres Verständnis der in den Ablagerungen dokumentierten Ökosysteme aus Jura- und Kreidezeit. Neben einem kurzen Abriss der Forschungsgeschichte werden die für die Zukunft geplanten Forschungsaktivitäten dargestellt. doi:10.1002/mmng.20010040113

The Late Jurassic to Early Cretaceous Tendaguru Beds (Tanzania, East Africa) have been well known for nearly a century for their diverse dinosaur assemblages. Here, we present sedimentological and palaeontological data collected by the German-Tanzanian Tendaguru Expedition 2000 in an attempt to reconstruct the palaeo-ecosystems of the Tendaguru Beds at their type locality. Our reconstructions are based on sedimentological data and on a palaeoecological analysis of macroinvertebrates, microvertebrates, plant fossils and microfossils (ostracods, foraminifera, charophytes, palynomorphs). In addition, we included data from previous expeditions, particularly those on the dinosaur assemblages. The environmental model of the Tendaguru Beds presented herein comprises three broad palaeoenvironmental units in a marginal marine setting: (1) Lagoon-like, shallow marine environments above fair weather wave base and with evidence of tides and storms. These formed behind barriers such as ooid bar and siliciclastic sand bar complexes and were generally subject to minor salinity fluctuations. (2) Extended tidal flats and low-relief coastal plains. These include low-energy, brackish coastal lakes and ponds as well as pools and small fluvial channels of coastal plains in which the large dinosaurs were buried. Since these environments apparently were, at best, poorly vegetated, the main feeding grounds of giant sauropods must have been elsewhere. Presumably, tidal flats and coastal plains were visited by dinosaurs primarily during periods of drought. (3) Vegetated hinterland. Vegetation of this environment can only be inferred indirectly from plant material transported into the other depositional environments. Vegetation was dominated by a diverse conifer flora, which apparently formed part of the food source of large herbivorous sauropods. Evidence from various sources suggests a subtropical to tropical palaeoclimate, characterised by seasonal rainfall alternating with a pronounced dry season during the Late Jurassic. In Early Cretaceous times, sedimentological and palaeontological proxies suggest a climatic shift towards more humid conditions. Die Tendaguru-Schichten von Tansania in Ostafrika (Oberjura bis Unterkreide) sind als Lagerstätte oberjurassischer Dinosaurier seit nahezu einem Jahrhundert weltweit bekannt. Anhand von sedimentologischen und paläontologischen Daten, die während der Deutsch-Tansanischen Tendaguru Expedition 2000 im Typus-Gebiet der Tendaguru-Schichten gewonnen wurden, werden Paläo-Ökosysteme rekonstruiert. Grundlage der Rekonstruktionen sind die Auswertung sedimentologischer Daten sowie die paläo-ökologische Analyse von Makroinvertebraten, Mikrovertebraten, pflanzlichen Fossilien und Mikrofossilien (Ostrakoden, Foraminiferen, Charophyten, Palynomorphen). Darüber hinaus werden Informationen über Dinosaurier berücksichtigt, die bei früheren Expeditionen gewonnen wurden. Das hier vorgestellte Ablagerungsmodell der Tendaguru-Schichten umfaßt drei Teilbereiche eines randlich marinen Sedimentationsraumes, die wie folgt gekennzeichnet werden können: (1) Lagunen-artige, marine Flachwasserbereiche, die oberhalb der Schönwetter-Wellenbasis lagen und unter deutlichem Einfluß von Gezeiten und Stürmen standen. Sie waren vom offenen Meer durch Barrieren, wie Ooidbarren und siliziklastischen Sandbarrenkomplexen, getrennt und wiesen einen leicht schwankenden Salzgehalt auf. (2) Ausgedehnte Wattgebiete und flache Küstenebenen. Dort befanden sich niedrig-energetische, brackische Strandseen und Teiche sowie Tümpel und kleinere Flußrinnen, in denen die großen Dinosaurier eingebettet wurden. Da diese Lebensräume bestenfalls dürftig bewachsen waren, müssen die Nahrungsquellen und der eigentliche Lebensraum der riesigen Sauropoden anderswo gelegen haben. Vermutlich wurden die Wattgebiete und Flachküsten von Dinosauriern vorrangig in den Trockenzeiten aufgesucht. (3) Bewachsenes Hinterland. Die Vegetation dieses Lebensraumes kann nur indirekt aus Pflanzenresten erschlossen werden, die in die anderen Ablagerungsraume transportiert wurden. Die Vegetation wurde von einer diversen Koniferenflora dominiert, die zumindest teilweise die Nahrungsgrundlage der großen, herbivoren Sauropoden bildete. Sedimentologische und paläontologische Indikatoren sprechen für ein subtropisches bis tropisches Klima wahrend der späten Jurazeit mit einem jahreszeitlichen Wechsel von Regenfällen und ausgeprägten Trockenzeiten. In der frühen Kreidezeit deutet sich ein Wechsel zu starker humiden Bedingungen an. doi:10.1002/mmng.20020050103

This work provides the first detailed taxonomic study of ostracod species from the Lower Cretaceous (Aptian) marginal coastal deposits of the Central Tunisian Atlas, the Kebar Formation, as well as biostratigraphic, paleoecological and paleobiogeographic implications. The ostracod fauna provides new insights into the depositional environment and biostratigraphic framework of the Kebar Formation, and is represented mainly by freshwater and brackish-water species among them, Perissocytheridea tunisiatlasica nov. sp., is newly described. The environmental setting of this formation comprises marginal-littoral conditions in its lower part, thus not exclusively non-marine/continental as assumed previously. The ostracod associations from the studied locality, Jebel Ksaira, indicate a minimum age of Early Aptian as recently attributed to the lower member of the Kebar Formation based on charophytes (presence of Late Barremian to Early Aptian Globator maillardii var. biutricularis Vicente and Martin-Closas, 2012), whereas an Early Albian age had been previously assigned to the Jebel Kebar site. The relative sea-level fall documented in the lower member of the Kebar formation at Jebel Ksaira might correspond to the 3rd order cycle major eustatic sea-level fall event starting at the base of the Aptian. Paleobiogeographically, the non-marine ostracod fauna newly discovered in the Kebar Formation shows some affinities to contemporaneous faunas of southern and western Europe, e.g. that of the uppermost Weald Clay Group of southern England (Cypridea fasciata subzone of Horne, 1995), West Africa, and possibly to eastern South America (Brazil). Hence, the studied ostracods further support the hypothesis of supraregional faunal exchange by passive ostracod dispersal during the Early Cretaceous – between Europe and Northern Africa on the one hand, and eastern South America/western Africa and North Africa on the other hand. This leads to the hypothesis that the Peri-Tethyan islands could have worked as effective bridges for non-marine ostracods to become widely dispersed passively by “island-hopping” of larger animals and thus, ultimately, facilitated intercontinental faunal exchanges between South America and Europe – potentially even Asia – via North Africa during the Early Cretaceous.

The non-marine Lower Cretaceous ostracod genusKegelinanew genus (Cypridoidea, Cyprideidae) is known from South America (Bahia state, eastern Brazil), West Africa (Gabon and ‘Congo'), and North America (Montana, Idaho and Wyoming, U.S.A.). It comprises five species:Kegelina anomala(Peck, 1941) new combination,Kegelina armata(Krömmelbein, 1962) new combination,Kegelina bisculpturata(Wicher, 1959) new combination,Kegelina depressa(Moura, 1972) new combination, andKegelina kegeli(Wicher, 1959) new combination, all of which having formerly been described as representatives ofCyprideaBosquet, 1852. The closer relationships ofKegelinanew genus among the Cyprideidae Martin, 1940 are discussed. Other potential species ofKegelinan. gen. are presumed to occur in northeastern China and Europe but remain to be examined.

A charophyte flora from the Upper Berriasian is described from the Lakota (Black Hills, South Dakota) and Cedar Mountain formations (San Rafael Swell, Utah) of the Western Interior Basin, United States of America. Whereas the latter is dominated by monotonous assemblages of the clavatoracean Nodosoclavator bradleyi (Harris, 1939), found in temporary lakes within palustrine facies, the flora of the Lakota Formation consists of more varied assemblages of the clavatoraceans N. bradleyi (Harris, 1939), Clavator grovesii grovesii Harris 1939, C. bilateralis Peck 1957 and early characeans (Mesochara sp. or Tolypella sp.). This flora was found in deposits related to permanent lakes in fluvial floodplains, i.e. lacustrine marls and limestones that do not show any evidence of subaerial exposure. To date, little is known about C. bilateralis, we provide a new definition on the basis of its particular structure, which shows lateral bract-cell units with a pinnate arrangement. This species appears to be endemic to North America and stratigraphically limited to the earliest Cretaceous. C. grovesii grovesii is part of a long-lasting charophyte lineage, which until now was considered to have originated in the Central Tethyan Archipelago (Europe) during the Early Berriasian, about 145 Ma, and limited to Eurasia until most of the Early Cretaceous. The new data presented here suggest that during the Berriasian this species was very broadly distributed, comprising North America, Europe and China.

The genus Praecypridea gen. nov. (Cypridoidea, Family Cyprideidae Martin, 1940) is described and thus far comprises four species: the type species Praecypridea acuticyatha (Schudack, 1998) comb. nov., Praecypridea postelongata (Oertli, 1957) comb. nov., Praecypridea suprajurassica (Mojon, Haddoumi & Charriére, 2009) comb. nov. and Praecypridea acuta (Moos, 1959 in Wicher, 1959) comb. nov. Representatives of the new genus have been described from the Middle to Late Jurassic of Europe, North America and Africa and the Early Cretaceous of South America, with other presumed representatives also occurring in the Early Cretaceous. Species of Praecypridea are considered to represent members of the ancestral lineage of the extinct genus Cypridea Bosquet, representatives of which flourished in non-marine habitats of latest Jurassic to Early Cretaceous age and account for the first period of abundance of the non-marine Cypridoidea.

The timespan represented by the hiatus between nonmarine Upper Jurassic (Early Berriasian?) and unconformably overlying Lower Cretaceous deposits throughout the North American Western Interior foreland basin has been under discussion for the entire 20th century and remains controversial to date. Ongoing research in revision of Early Cretaceous nonmarine ostracods of some respective North American formations leads to a breakthrough concerning the verification of their biostratigraphic utility as well as their subsequent application. These ostracods are not as endemic as hitherto believed and can be used for supraregional and regional correlation, as well as improvement of the age determination of North American units. New results strongly suggest a maximum age of Late Berriasian to Valanginian (∼ 142–138 Ma) for the lower part of the Lakota (Black Hills area, South Dakota) and Cedar Mountain (Utah) formations. A pre-Aptian maximum age for the Lakota Formation is supported by early mammals. These biostratigraphic results affect the correlatable formations as well, and therefore have broad implications on basin-related geologic and paleontologic topics that are overviewed and discussed herein. The central issue hampering an integrated synthesis of the foreland basin is its yet imprecise chronostratigraphic framework and documentation. Temporal relationships between the gologic processes of the basin and their control factors are still insufficiently calibrated or controversial. Detailed ongoing revision of North American Early Cretaceous nonmarine ostracods demonstrates their applicability, utility, and further potential as tool for improvement of the chronostratigraphy of the Western Interior foreland basin at both small and large scales. These ostracods also foster understanding of animal (e.g. early mammals and dinosaurs) and plant (angiosperms) evolution on the North American continent and show promise of providing age determinations for single-sample horizons in the near future.

Revisitation of the famous Late Jurassic/Early Cretaceous dinosaur locality of Tendaguru by a German–Tanzanian expedition in summer 2000 resulted in a new standard section. Micropalaeontologic samples from this section yielded a marine and nonmarine, partially mixed ostracod fauna consisting of 40 taxa and some charophyte gyrogonites and utriculi. A few marine taxa provided biostratigraphic information, although comparable faunas from the West Indian–Madagascan–East African faunal province are stratigraphically older (Middle/Late Jurassic), fully marine and strongly endemic. An (Middle) Oxfordian age is suggested for the lower part of the Tendaguru formation. Nodosoclavatoroid utriculi (Charophyta) suggest that the Jurassic/Cretaceous boundary may be located lower in the section than supposed previously, i.e. in the Trigonia smeei member rather than in the Upper Saurian member. In biogeographical terms, the marine ostracod fauna is relatively endemic and has most similarities with that known from eastern Tanzania. Only a few faunal links to Madagascar, Northwest India and Somalia exist, and there are no links to South Africa. Ostracods and charophytes also provided palaeoecological data for specific horizons. In the lower part of the Middle Saurian member a regression is documented. While the nonmarine Late Jurassic/Early Cretaceous ostracods of Tendaguru are not applicable to biostratigraphy so far, they are important because the nonmarine setting is unique in this area of the Tethys.

Mammalian diversity in North America shifted significantly during the Early Cretaceous, from archaic groups dominant in the well-sampled faunas of the Late Jurassic to advanced forms (including early members of modern clades) by the Albian—Cenomanian. However, the dynamics of this transition are poorly understood, since faunas of earliest Cretaceous age are unknown. Here we describe the first fossil mammals from exposures of the Lakota Formation in the Black Hills of South Dakota, a unit correlated with the upper Berriasian—lower Barremian and positioned stratigraphically between the underlying Morrison Formation and Aptian—Albian units exposed elsewhere in North America. The mammalian fauna from the Lakota Formation is transitional with regard to the North American fossil record, representing a broad spectrum of both Jurassic and Cretaceous lineages: present are “plagiaulacidan” multituberculates allied with Late Jurassic Allodontoidea and Early Cretaceous Plagiaulacoidea; the geologically youngest dryol...

On several occasions at paleontology-, geology-, and stratigraphy-related meetings during the past years, I noticed that many colleagues, even micropaleontologists, are not (anymore!) aware of the fundamental application potential of pre-Quaternary, fresh- and brackish-water ostracode fossils. Ostracodes, aquatic crawling or swimming microcrustaceans with a calcified bivalved shell and high fossilization potential, have rarely been considered as a major tool in biostratigraphy, fading mostly into the background compared to other fossil groups in the marine realm. In the continental realm, however, ostracodes are often the most common and abundant fossils, whether in freshwater or saline deposits. Yet, supraregional and intercontinental biostratigraphy based on aquatic organisms sounds absurd. It is not, however! Fresh- and brackish-water ostracodes have developed different strategies and mechanisms to facilitate their adaptation to temporary habitats and dispersal in such settings. Recent fresh- and brackish-water ostracodes, just as did their fossil counterparts, have a high potential to be passively distributed over long distances and across migration barriers by wind and larger animals, particularly owing to the desiccation- and freeze-resistant resting eggs of major groups (e.g., Horne and Martens, 1998) and, therefore, are a strong candidate for biostratigraphic application. Dealing with biostratigraphy of Lower Cretaceous continental deposits, it is important to understand that in most regions, except western Europe, we are not necessarily talking about high-resolution biostratigraphy. For example, many publications to-date on such deposits in Central Asia, South America, and Africa only provide an age of Early Cretaceous without further subdivision, and no attribution to stages. In the North American Western Interior foreland basin, Lower Cretaceous continental deposits are widely regarded to be of pre-middle Albian age, or to range from Aptian to Albian, sometimes Barremian–Albian in age (e.g., Cobban and Reeside, 1952; Peck, 1959; Mateer et al., 1992; Dyman et al. 1994; Way et …