Isotopic data (C and O) derived from Callovian (Middle Jurassic) mollusks (bivalves, ammonites and belemnoids, including true belemnites and Belemnotheutis) are presented from a narrow stratigraphic interval in the Christian Malford Lagerstätte, UK. The exceptionally well-preserved mollusks include aragonite-calcite pairs precipitated by individual belemnite animals that enable an assessment of possible “vital” effects and the reliability of using belemnite calcite to determine ocean water compositions. The oxygen isotope data derived from the calcitic rostra of the belemnites (Cylindroteuthis) show modest variability, ranging from −1.2 to 0.9‰ (V-PDB), while their accompanying aragonitic phragmocones range from −1.4 to 0.0‰. Data derived from the ammonite Kosmoceras show some scatter, with oxygen isotope values varying from −3.6 to −0.2‰. The aragonite data from Cylindroteuthis, Kosmoceras and Belemnotheutis all overlap, suggesting they inhabited similar (surface) water depths. However, the corresponding data from the calcitic rostra of the Cylindroteuthis specimens suggest temperatures ~ 5°C cooler. As we have analyzed aragonite-calcite pairs, the discrepancy cannot be explained by environmental effects. Though clearly a vital effect, it is difficult to resolve whether the temperatures derived from the aragonite (phragmocone) are too warm or from the calcite (rostrum) are too cool. Consequently, the applicability of standard paleotemperature equations to Cylindroteuthid belemnite rostra remains unproven. Sequentially sampled ontogenetic isotope data derived from Belemnotheutis phragmocones reveal only modest δ¹⁸O variation, consistent with limited movement between warmer (shallower) and cooler (deeper) waters. A coincidental systematic pattern of δ¹³C enrichment may signal changes in metabolic activity associated with a shift in ecology or feeding with age.

The horned dinosaur Centrosaurus apertus from the Belly River Group (Campanian) is represented by multiple articulated skulls and skeletons, and is particularly notable for its occurrence in dozens of large-scale monodominant bonebeds, which have been found in the Dinosaur Park Formation across southern Alberta and Saskatchewan. Here we present a detailed taphonomic analysis of the first large-scale Centrosaurus apertus bonebed (McPheeters bonebed) from the Oldman Formation of southeastern Alberta. The McPheeters bonebed rivals the richest bonebeds in the Dinosaur Park Formation in terms of bone density and size, and the complete disarticulation of elements. The bonebed occurs in an overbank facies and is dominated by small bone clasts, suggesting that only low energy water current contributed to the formation of the bonebed before its final burial event. Patterns of taphonomic modification suggest that bones experienced little weathering, breakage, or scavenging. In turn, these conclusions are compatible with an overall interpretation of rapid burial in humid conditions after the disarticulation of elements. These taphonomic features are virtually identical to those seen in the well-documented bonebeds of this species in the Dinosaur Park Formation, which are interpreted to represent mass death events caused by seasonal tropical storms and associated large-scale flooding. Late Cretaceous dinosaur species typically have small geographic and stratigraphic ranges defined by the extent of single geological formations. The new bonebed extends the distribution of Centrosaurus apertus to the upper Oldman Formation, which is interpreted as more inland than the coastally influenced Dinosaur Park Formation, and suggests that mass death events related to seasonal tropical storms occurred over a broader geographic area and in a greater range of paleoenvironments than previously documented.

Devonian massive graphitic marble and calc-silicate schist, belonging to the Lower Formation of the Nevado-Filábride Complex of the Internal Zones of the Betic Cordillera, crop out extensively near Águilas (Murcia, SE Spain). These rocks contain a rich fossil record even though they have undergone Alpine metamorphism and deformation (350–480°C; 2 Kb). In this paper, we focus on the taphonomic characteristics of the fossil assemblages to infer the depositional processes that can be reconstructed even after metamorphism. The most abundant fossils are crinoids, followed by phacelloid colonial rugose corals, brachiopods, cephalopods (ammonoids and orthoceratids), and possible gastropods and benthic foraminifers. Crinoids occur as isolated columnal ossicles, as well as articulated portions of columns (pluricolumnals). One complete calyx was also found. Taphonomically delicate crinoids are preserved in the calc-silicate schist beds. In the massive marble beds, crinoids occur mostly as disarticulated ossicles, but they still bear delicate ornamental features. Some corals preserve external walls. The low degree of abrasion indicates disarticulation of the crinoids due to exposure in the taphonomic active zone (TAZ), but under low-energy conditions. Articulated crinoids are preserved due to catastrophic burial events. The preservation of the fauna allows the differentiation of background versus event biostratinomic processes even after being highly altered by metamorphism.

Micro-CT analysis has been established as a useful, non-destructive method for assessing the inner arrangement of rhodoliths. In this study, micro-CT analyses and sectioning techniques are used for void space assessment, the reconstruction of growth histories, and their related environmental conditions in present-day rhodoliths from Giglio Island (Tyrrhenian Sea, Italy). The rhodoliths are investigated with respect to shape, taxonomy and growth forms of coralline red algae, constructing fauna and flora, degree of porosity, and types of void formation. Porosity within the nodules is calculated using image processing software based on slab surfaces and micro-CT, enabling recognition of different void types at various scales as well as their distribution throughout the rhodoliths.

The studied rhodoliths range in sizes from 4 to 16 cm and are spheroidal to sub-spheroidal in shape. The nodules are dominated by coralline red algae and associated with subordinate serpulid worm tubes and bryozoans. Calculated porosity values range from 3 to 41% in volume. Two different types of porosity were distinguished within the rhodoliths: (1) constructional voids are present as primary voids present within single cells and conceptacles and as voids produced by conjoined protuberances of coralline algal thalli, and (2) destructional voids are caused by dissolution and decay of nuclei as well as soft-body organisms and a wide range of bioerosion, including Gastrochaenolites and Trypanites ichnotaxa. The degree of bioerosion (bioerosion index, BI) ranges from low (BI  =  2) to moderate (BI  =  3).

The calcareous microproblematicum Halysis Høeg 1932 occurs in abundance in Ordovician fine-grained, reddish carbonate mounds rich in spar-cemented cavities (Katian, Tarim Basin, NW China). Morphological analysis of Halysis suggests a U-shape skeleton punctually attached to a soft substrate of carbonate sand and silt. The skeletons have a maximum width of 12 mm and consist of laterally branching tubes. The tubes display circular to laterally flattened outlines with a mean diameter ~ 125 μm. The tube walls consist of an inner and an outer layer of microcrystalline calcite, and a central layer of imbricated, radially arranged calcite tablets. An affinity of Halysis with extant siphonous calcareous green algae (Bryopsidales, Udoteaceae) is likely. If correct, Halysis represents a case of a green alga that acquired its skeleton de novo in accordance with sea-water chemistry (low genetic control, low-magnesium calcite, Ordovician calcite sea). Halysis carbonate mounds are low-relief, internally bedded, shallow-water packstone to grainstone banks. Spar-cemented cavities are Halysis-supported shelter cavities (~ 90%) and depositional cavities (~ 10%) produced from sediment-laden flows. The mounds formed as part of a shallow-subtidal carbonate ramp dominated by algal-pellet sand sheets. Autocyclic drivers (sand propagation via tides, storms) produced increments of sediment burial followed by episodes of omission and algal growth. These mounds should not be mistaken for “shallow-water carbonate mudmounds” nor for algal framework reefs. In terms of facies, texture, biostratinomy and primary porosity, these mounds are considered a miniature version of bryozoan-rich carbonate banks. Twisted and imbricated aggregates of fronds of Halysis produced shelter cavities making up ~ 5% of the total mound rock volume, thereby reducing accommodation space in sufficient quantity to explain mound formation. A review shows that Halysis presented herein displays the largest and most robust intrageneric growth form compared to occurrences of more basinal settings (Ordovician) as well as much younger carbonate deposits (Silurian to Devonian).

A small (3.4 cm) coprolite from the Upper Cretaceous (middle Campanian age) Coachman Formation in South Carolina, contains six cervical vertebrae from a very small, freshwater, trionychid turtle. Four of the vertebrae included in the coprolite are aligned and partly articulated. The coprolite shows typical selachian heteropolar shape with traces of spiral morphology, and is attributed to one of several common lamniform shark taxa in the associated marine fauna, most probably Squalicorax kaupi. Based on the minute size of the included vertebrae, with the largest 4.5 mm long, the turtle must have been very small and likely newly hatched. Assuming the selachian producing the specimen was a marine or estuarine species, this coprolite specimen indicates that the shark was feeding in or proximal to a fluvial environment, as observed in modern species of Carcharhinus. Given the small size of the coprolite, the shark was likely also small, suggesting that a juvenile Late Cretaceous shark was feeding far upstream, perhaps near its pupping area.

The significant increase of abundance and expansion of depositional environments that produced unusual sediments in the Early Triassic indicates stressed ecosystems in the aftermath of the Permian–Triassic (P–Tr) mass extinction. As one of the characteristically common Early Triassic carbonate sediments, ooids provide a potential proxy to refine understanding of the biotic and environmental stresses during this time through analysis of their formation and size variations. A case study from South China and a global review are presented herein to explore the interrelations between occurrences of oolites and ooid size variations with biotic and environmental changes. Correlations between oolites and various biotic and environmental changes suggest a strong correspondence with episodes of euxinia/dysoxia but less so with skeleton abundance and temperature changes, implying complex interactions between multiple biotic and environmental anomalies in the aftermath of the P–Tr extinction. The episodic occurrence pattern of oolites from the end-Permian through the Early Triassic coincides with the multiple crises of the P–Tr mass extinction and its aftermath. The global increase in size of ooids during the early stage of the P–Tr mass extinction aftermath indicates the most severe and extensive conditions of devastation for ecosystems. The single occurrence of giant ooids in the Nanpanjiang Basin within the Olenekian implies local higher ecosystem stress than other areas. This analysis of ooid size variations and the paleoceanographic implications suggests that the size of ooids could be an appropriate quantified sedimentary proxy for ecosystem devastation with varied temporal and spatial ranges.