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Cylindrical borings assigned to ichnospecies Trypanites mobilis Neumann, Wisshak & Bromley, 2008, are common in bulbous echinoid spines (Tylocidaris baltica and Ty. vexilifera) and globular calcareous sponges (Porosphaera globularis) from the Maastrichtian chalk and Danian limestone of eastern Denmark. Trypanites mobilis was originally described as being restricted to these substrates but is here reported also from crinoid fragments and asteroid ossicles. A revised diagnosis of Tr. mobilis is proposed to accommodate the broader spectrum of host bioclasts and the fact that some bioclasts, notably Porosphaera, are fully penetrated. Trypanites mobilis is interpreted as a mobile shelter for sipunculan worms and the first appearance of this trace fossil around the Early/Late Cretaceous transition is inferred to reflect intensified predation pressure, and a general shortage of hard substrates on the muddy chalk sea floor. Trypanites mobilis is very common in the Maastrichtian of Denmark. It then nearly disappears in the lower Danian, re-occurs in the middle Danian, at first with smaller sizes and in low numbers, before becoming numerous and large-sized again around the middle/upper Danian transition. The near absence of Tr. mobilis in the lower Danian and its low abundance in the middle Danian is suggested to reflect that the ‘substrate makers’ were affected by ecological instability following the Cretaceous–Palaeogene mass extinction. Trypanites mobilis disappeared after the mid/late Danian transition, i.e. before extinction of its Danian substrate-maker Ty. vexilifera. [ABSTRACT FROM AUTHOR]

A new trace fossil, Koptichnus rasmussenae, was recently reported from the Cretaceous of Denmark. This burrow is thickly lined with cuboids that the tracemaker cut from siliceous sponges. A newly discovered specimen from the lower Selandian Kerteminde Marl, found in a loose boulder in the Gundstrup gravel pit (Fyn, Denmark), extends the stratigraphical range of this ichnotaxon from the previously known Coniacian to the middle Paleocene and demonstrates that this distinct behaviour of harvesting and shaping building material survived the K-Pg extinction event. [ABSTRACT FROM AUTHOR]

The effects of the Cretaceous‐Paleogene (K/Pg) mass extinction (~66 Ma) on marine primary and export productivity remain debated. We studied changes in carbon and nitrogen cycling in eight neritic and upper bathyal sections with expanded K/Pg boundary clay layers in the western Tethys and northeastern Atlantic Ocean, by measuring stable carbon isotopes of bulk carbonate (δ13Ccarb) and organic matter (δ13Corg), nitrogen isotopes in bulk organic matter (δ15N), and selected compound‐specific carbon isotopic records (δ13Clipid). Negative carbon isotope excursions (CIEs) in δ13Ccarb, δ13Corg, and δ13Clipid are temporally and spatially heterogeneous as well as decoupled from each other, suggesting that factors affecting the δ13C of dissolved inorganic carbon, as well as isotopic fractionation during carbon fixation across the K/Pg, are more complex than commonly assumed. The negative CIEs in δ13Corg and δ13Clipid at each site are smaller in amplitude and shorter in duration than those in δ13Ccarb, but in most sections both carbon pools recovered to preboundary conditions within the time of deposition of the boundary clay layer (<103–104 Kyr) or shortly thereafter. This rapid recovery is supported by limited δ15N data, which mostly suggests moderate or minor changes in redox conditions (except in Denmark), marine productivity, and phytoplanktonic nitrate utilization in the earliest Danian. Our results indicate that carbon cycling and primary productivity in neritic and upper bathyal regions recovered to preboundary levels faster (<104Kyr) than in oceanic regions (105–106 years), likely sustained by resilient noncalcifying phytoplankton with resting stages, consistent with modeling and proxy studies. Plain Language Summary: Sixty‐six million years ago, at the boundary between the Cretaceous and Paleogene Periods (K/Pg boundary), a meteorite impacted the Earth during a time of active volcanism causing the mass extinction of marine and terrestrial species. Despite decades of research, the consequences of the mass extinction to marine photosynthesis and the cycling of carbon in the ocean remain contentious. We investigated the light and heavy stable isotopes of carbon preserved in rocks of ancient seafloor along continental margins of the western Tethys and northeastern Atlantic Oceans to establish for how long the cycling of carbon may have been disrupted. Our results indicate that the response of marine productivity and carbon cycling following the impact was heterogenous for thousands and tens of thousands of years but that it recovered to pre‐K/Pg boundary levels hundreds of thousands of years earlier than open ocean regions. We suggest that resilient phytoplankton without carbonate skeletons living along continental margins may have recolonized surface waters relatively quickly after this mass extinction event. Key Points: Carbonate and organic matter stable isotope records were obtained from eight neritic and upper bathyal sectionsIsotopic signatures are spatially and temporally heterogeneous, and the organic and inorganic carbon pools are decoupledCarbon cycling and marine productivity may have recovered faster than pelagic sites and within the deposition of the boundary clay layer [ABSTRACT FROM AUTHOR]

Profound changes in both marine and terrestrial biota during the end-Triassic mass extinction event and associated successive carbon cycle perturbations across the Triassic-Jurassic boundary (T-J, 201.3 Ma) have primarily been attributed to volcanic emissions from the Central Atlantic Magmatic Province and/or injection of methane. Here we present a new extended organic carbon isotope record from a cored T-J boundary succession in the Danish Basin, dated by high-resolution palynostratigraphy and supplemented by a marine faunal record. Correlated with reference C-isotope and biotic records from the UK, it provides new evidence that the major biotic changes, both on land and in the oceans, commenced prior to the most prominent negative C-isotope excursion. If massive methane release was involved, it did not trigger the end-Triassic mass extinction. Instead, this negative C-isotope excursion is contemporaneous with the onset of floral recovery on land, whereas marine ecosystems remained perturbed. The decoupling between ecosystem recovery on land and in the sea is more likely explained by long-term flood basalt volcanism releasing both SO2 and CO2 with short- and long-term effects, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Located to the north of the Stevns Klint Peninsula (Denmark), Kulstirenden shows the transition from Cretaceous chalks to Danian carbonates across the Cretaceous – Paleogene (K/Pg) boundary. The K/Pg boundary at Kulstirenden is represented by the Fiskeler Member (Fish Clay), a streaked marl interval with a smectite rich, red oxidised layer at its base marking the boundary. The Fiskeler Member is important as it includes the iridium concentration linked to the bolide impact which may have caused the end-Cretaceous mass extinction and is at its maximum thickness at Kulstirenden (c.45 cm). Calcareous dinoflagellate cysts (Calciodinelloideae) have been investigated from within the fine fraction (45–125 μm) at Kulstirenden in order to understand the ecological implications of these enigmatic microfossils. Several species were found within the Fiskeler Member, including Orthopithonella collaris, Rev. Palaeobot. Palynol. 115, 69–77). This species is of particular interest as it demonstrates reduced paratabulation and may indicate a transgressive period immediately after the K/Pg boundary event. O. collaris has been described as a morphotype formed under post-K/Pg environmental conditions and is, therefore, described as a “disaster” taxon that marks the K/Pg boundary at Stevns Klint. The distribution of this taxon is more extensive than previously documented, disappearing as carbonate sedimentation returned in the Cerithium Limestone Member of the Danian. Several calcareous microfossil specimens that were found cannot be associated with the dinoflagellates and display Bolboforma-like features. While the origins of Bolboforma are enigmatic, the current finding expands their stratigraphic range and suggests an appearance of this group of organisms found at Stevns Klint may give an insight into the inception of this group into the earliest Danian. [Copyright &y& Elsevier]

The end-Triassic mass extinction (ETE) is thought to have been triggered by widespread eruption and emissions of volcanic and contact metamorphic carbon and sulfur gases from the Central Atlantic Magmatic Province (CAMP) flood basalts. Although palynological studies of shallow marine deposits in the basins of Denmark and Germany suggest that deforestation and catastrophic soil loss occurred during the CAMP volcanism and ETE interval, the intensity and timing of continental weathering in the region of northwestern Tethys Ocean remain unclear. Here we present Sr, C, and O isotope data, as well as multivariate statistical analyses of major element contents, for carbonate–clastic deposits in the Kardolína section, Slovakia, to develop a continental weathering record in the NW Tethys during the ETE event. This section consists of a shallow marine carbonate sequence in the Rhaetian Fatra Formation and the overlying Hettangian Kopieniec Formation. The Fatra Formation represents ramp facies deposits that formed in a restricted pull-apart basin of the Fatric Zone along the southern margin of the Bohemian Massif in the region of northwestern Tethys. Carbon isotope analysis of the limestones revealed two negative carbon isotope excursions (NCIEs) in the uppermost Fatra Formation. These two NCIEs occurred in the latest Rhaetian and can be compared to the "precursor" and "initial" NCIEs reported for the northwestern Tethys. Strontium isotope analysis of the limestones revealed an abrupt increase in Sr isotope ratios between the precursor and initial NCIEs, which indicates that continental weathering of the Bohemian Massif increased rapidly in the latest Rhaetian. Multivariate analysis of major element contents in the carbonate rocks also shows that intense chemical weathering of the hinterland was accelerated after the precursor NCIE, supporting the inferences drawn from Sr isotopes. Furthermore, our study reveals that the carbonate depositional environments of the Fatra Formation changed to the formation of specific Fe-rich oolites with increased continental weathering after the precursor NCIE. The concentrations of redox-sensitive major elements (e.g., Mn and Fe) and multivariate analysis of the major element data suggest that the Fe-rich oolites were formed by an influx of O-depleted water into the shallow water depositional environment of the Fatra Formation. A possible origin for this O-depleted water is the oxygen minimum zone (OMZ) that formed at intermediate water depths in European basins (e.g., the German and Eiberg basins) during the latest Rhaetian. Our results suggest that the marine environment in the European basins may have developed an OMZ due to the increase in continental weathering during the latest Rhaetian, and these environmental changes may have had an important role in the marine ETE event. • Sr, C, and O isotope data of the Rhaetian succession in Slovakia were determined. • Two negative carbon isotope excursions (NCIEs) were detected in latest Rhaetian. • Abrupt increase in Sr isotope ratios recognized between these two NCIEs. • Continental weathering was temporarily enhanced during the end-Triassic extinction. • Intense weathering led to development of oxygen minimum zone in NW Tethys. [ABSTRACT FROM AUTHOR]

Only few of the brachiopod species that lived in the Late Cretaceous Chalk Sea of northern Europe survived the mass extinction at the Cretaceous–Paleogene boundary. However, a rich brachiopod fauna rapidly evolved from the survivors and most of the vacant niches were filled in by the middle Danian when a large cool-water, subphotic coral-bryozoan mound complex was developed at Faxe in the eastern part of the Danish Basin. The brachiopod fauna of the complex comprises 17 species dominated by micromorphic species of similar types as those known from the Upper Cretaceous, Maastrichtian chalk from the same region. All species are found in the coral mound facies and six of the species are restricted to this facies. Large-sized species are rare both in terms of species numbers and abundance. One species is adapted to a life between the branches of the cool-water hexacorals Dendrophyllia candelabrum and Oculina becki. Secondarily free-living species are close to absent. This is in contrast to the Maastrichtian chalk fauna where this group includes 10 species (~24% of the total brachiopod fauna). The otherwise great similarity in morphological adaptations in the brachiopods from the Maastrichtian chalk and the Danian coral mounds is remarkable and somewhat surprising as the latter almost lacks soft substrates. The Danian brachiopod fauna essentially represents a continuation of the Maastrichtian fauna, but in a very different habitat. The similarity between the two faunas is explained by the abundance of small, hard substrates, notably bryozoans in both environments. The brachiopods from Faxe are one of the very few ancient examples of a rich brachiopod fauna from a coral mound environment. • Rare example of a rich brachiopod fauna from a coral mound environment • The brachiopod fauna of the subphotic coral-bryozoan complex comprises 17 species. • The fauna represents descendants from the few survivors of the K/Pg mass extinction. • Six ecological groups are recognized based on interpreted mode of life. [ABSTRACT FROM AUTHOR]