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The rise of calcareous nannoplankton in Mesozoic oceans has deeply impacted ocean chemistry and contributed to shape modern oceans. Nevertheless, the calcareous nannoplankton colonization of past marine environments remains poorly understood. Based on an extensive compilation of published and unpublished data, we show that their accumulation rates in sediments increased from the Early Jurassic (~ 200 Ma) to the Early Cretaceous (~ 120 Ma), although these algae diversified up to the end of the Mesozoic (66 Ma). After the middle Eocene (~ 45 Ma), a decoupling occurred between accumulation rates, diversity and coccolith size. The time series analysed points toward a three-phase evolutionary dynamic. An Invasion phase of the open-ocean realms was followed by a Specialization phase occurring along with taxonomic diversification, ended by an Establishment phase where few small-sized species dominated. The current hegemony of calcareous nannoplankton in the World Ocean results from a long-term and complex evolutionary history shaped by ecological interactions and abiotic forcing. [ABSTRACT FROM AUTHOR]

The global Mesozoic sea-level rise contributed to the stepwise flooding of the Central European Basin (CEB) across the T-J transition and transformed the CEB from a late Triassic inland playa to an early Jurassic semi-enclosed inland sea. The calibration of sections from North Germany and Thuringia using high-resolution palynomorph and ammonite biostratigraphy contributes to the improved temporal and spatial resolution of this decisive period. The herein proposed Deltoidospora - Concavisporites (DC) Zone, placed between the Rhaetian Ricciisporites - Polypodiisporites (RP) Zone and the Hettangian Pinuspollenites - Trachysporites Zone, marks the transitional zone of overlapping Rhaetian and Hettangian palynomorphs in brackish-marine, brackish and terrestrial environments of the North German Basin (NGB). Thus, the DC Zone enables the identification of the T-J transition in the NGB. Following a short-term ingression in the late Norian Corollina - Porcellispora Subzone, the first Rhaetian transgression contributed to substantial marine-terrestrial facies shifts. The diachronous transgressive onlap of brackish-marine strata culminated in a first Rhaetian maximum flooding in the upper Corollina - Enzonalasporites Zone to lower Rhaetipollis - Limbosporites (RL) Zone. After a regressive maximum in the middle RL Zone, the next transgression culminated in a second Rhaetian maximum flooding in the upper RL Zone. Following the end-Triassic regression, herein assigned to the upper RP Zone, the diachronous transgressive onlap of marine shales marks the change to marine Jurassic environments. The herein proposed Deltoidospora - Concavisporites (DC) Zone, placed between the Rhaetian Ricciisporites - Polypodiisporites (RP) Zone and the Hettangian Pinuspollenites - Trachysporites Zone, marks the transitional zone of overlapping Rhaetian and Hettangian palynomorphs in brackish-marine, brackish and terrestrial environments of the North German Basin (NGB). Thus, the DC Zone enables the identification of the T-J transition in the NGB. At the western gate of the CEB, the onset of marine Hettangian strata with ammonites, dated as the P. erugatum Biohorizon at St. Audrie's Bay, postdates the base Hettangian GSSP by ~ 250 kyr. From there to Thuringia, the diachronous onlap of marine Hettangian strata with ammonites, herein dated as the P. plicatulum Biohorizon, took place over ~ 100 kyr. The first Jurassic maximum flooding is dated as the interval of the P. psilonotum to P. plicatulum Biohorizons (lower Planorbis Zone). Rhaetian–Hettangian 3rd-order sequences of the CEB correlate with contemporaneous sequences described from Tethyan and peri-Tethyan basins pointing to circum-Tethyan eustatic cycles. The 4th-order sequences are evident in the Rhaetian-Hettangian, but only a set of Rhaetian 4th-order sequences can be correlated in the NGB so far. [ABSTRACT FROM AUTHOR]

Ecosystems changed dramatically during the Mesozoic marine revolution, including the rise of decapod crustaceans such as lobsters, shrimp, true crabs, and squat lobsters. However, quantitative patterns of decapod biodiversity through geological time are virtually unknown. This hampers our understanding of their importance in past ecosystems and timing and causes of their radiations and extinctions. Based on our compilation of ~1300 Mesozoic decapod species, we document a long-term shift in diversity of dominant groups, marked by the first appearance and increasing presence of true crabs and, to a lesser extent, squat lobsters. By the end of the Mesozoic, true crabs became the primary contributor to decapod diversity, a pattern that has persisted until the present time. This "Mesozoic decapod revolution" was advanced by a major radiation of reef-dwelling crabs, which coincided with a dramatic expansion of reefs in the Late Jurassic. The subsequent collapse of reefs near the end of the Jurassic was mirrored by a sharp (albeit temporary) drop in decapod diversity driven primarily by extinctions of numerous species of crabs. This concurrent decline also suggests that decapods inhabiting reefs, especially obligatory reef dwellers, may face elevated extinction risks today as reef ecosystems continue to deteriorate. The reef-related diversification of Late Jurassic decapods and the significant correlation between decapod diversity and reef abundance throughout the Mesozoic underscore the macroevolutionary importance of biotic interactions and ecosystem engineering. [ABSTRACT FROM AUTHOR]

Abstract: Patterns of uranium–molybdenum covariation in marine sediments have the potential to provide insights regarding depositional conditions and processes in paleoceanographic systems. Specifically, such patterns can be used to assess bottom water redox conditions, the operation of metal-oxyhydroxide particulate shuttles in the water column, and the degree of water mass restriction. The utility of this paleoenvironmental proxy is due to the differential geochemical behavior of U and Mo: (1) uptake of authigenic U by marine sediments begins at the Fe(II)–Fe(III) redox boundary (i.e., suboxic conditions), whereas authigenic Mo enrichment requires the presence of H2S (i.e., euxinic conditions), and (2) transfer of aqueous Mo to the sediment may be enhanced through particulate shuttles, whereas aqueous U is unaffected by this process. In the present study, we examine U–Mo covariation in organic-rich sediments deposited mostly in the western Tethyan region during oceanic anoxic events (OAEs) of Early Jurassic to Late Cretaceous age. Our analysis generally confirms existing interpretations of redox conditions in these formations but provides significant new insights regarding water mass restriction and the operation of particulate shuttles in depositional systems. These insights will help to address contentious issues pertaining to the character and origin of Mesozoic OAEs, such as the degree to which regional paleoceanographic factors controlled the development of the OAEs. [Copyright &y& Elsevier]

Abstract: The Early Cretaceous is punctuated by widespread biocalcification crises. These are characterized by decrease in the carbonate platform growth and, in the pelagic realm, by a decline in Nannoconus relative abundance in the calcareous nannofossil assemblages. The Valanginian Nannoconus decline started before the positive δ13C excursion characterizing the Weissert Event. The nannoconid decline is investigated in two sections of the Vocontian Basin, La Charce and Vergol, which are biostratigraphically well-constrained and contain well-preserved calcareous nannofossils. Absolute and relative abundances of Nannoconus show a polyphased decline, with a first decrease in the interval from the Campylotoxus to the Verrucosum Ammonite Subzones before the positive δ13C shift, and a second decrease from the end of the Peregrinus to the base of the Radiatus Ammonite Zones concomitant with the long-term decrease in δ13C. These two declines are separated by an important increase in the Nannoconus abundance from the Verrucosum to the Peregrinus Ammonite Subzones concomitant with a slight short-term decrease of δ13C. Biometric analysis shows size changes of N. steinmannii and N. kamptneri along the nannoconid decline. The patterns of abundances and size changes seem to be related to paleoenvironmental changes, mainly characterized by a temperature decrease and variable nutrient supply. The described Valanginian nannoconid recovery seems to occur during the most intense phase of the cooling event and is recorded in the Vocontian basin as well as in the Atlantic and Tethys Oceans. These spatial correlations suggest a supra-regional character for the Valanginian nannoconid recovery event best recorded in the Vocontian Basin and at low latitudes. [Copyright &y& Elsevier]

The article presents the study on the Toarcian oceanic anoxic events (T-OAE) during the Toarcian period. The study shows that black shales were deposited on the pericontinental shelves of Pangaea during the early Toarcian period and is believed to represent oceanic anoxic event. The study also mentions that the distribution of black shales during the T-OAE is similar to the Mesozoic OAE.

Focuses on the evidence which shows that Earth's climate was much warmer during the Cretaceous period than it is today. List of material evidence; Analyses of sediments retrieved from a drifting ice island; Testament produced by Jenkyns and colleagues.