A formerly unknown fossil-bearing locality in the lower part of the Witpoort Formation (Witteberg Group, Cape Supergroup) is described from the Eastern Cape (South Africa). Uniquely for these strata, it provides evidence for a back-barrier lagoon hosting a monospecific lingulid brachiopod fauna. This represents the youngest record of marine invertebrates within the Cape Supergroup. The occurrence extends the age range of the genus Dignomia Hall into the Famennian Stage, contrary to previous estimates of an Ordovician to mid-Devonian range. Abundant lingulid brachiopod valves are associated with plant and fish remains within a laterally extensive, up to nine-meter-thick mudstone. Shell compressions are concentrated in patches within the upper portion of the horizon and are preserved parallel to bedding as well as perpendicular and oblique to bedding (apparently in situ). Plant fossils exhibit a greater degree of transport than in other studied Witpoort Formation mudrock layers (Coombs Hill and Waterloo Farm). The monospecifity of the shelly invertebrate fauna derives from environmental stress and lingulid brachiopods' unusual ability to tolerate fluctuating environmental conditions, including salinity, oxygen levels, and temperature. Ichnofauna within the deposit include, among others, Nereites and ‘Spirophyton’, suggesting opportunistic colonization of the substrate by deposit feeding invertebrates in a marine-dominated backshore setting. The Late Devonian was a time of global environmental disequilibrium, characterized by periodic flooding of continental margins and massive biotic overturn. Ongoing research into eustatic and environmental changes recorded within the Witpoort Formation uniquely provide insights into high latitude conditions during the Famennian.

The preservation of organic biosignatures during the Proterozoic Eon required specific taphonomic windows that could entomb organic matter to preserve amorphous kerogen and even microbial body fossils before they could be extensively degraded. Some of the best examples of such preservation are found in early diagenetic chert that formed in peritidal environments. This chert contains discrete domains of amorphous kerogen and sometimes kerogenous microbial mat structures and microbial body fossils. Our understanding of how these exquisite microfossils were preserved and the balance between organic degradation and mineral formation has remained incomplete. Here, we present new insights into organic preservation in Proterozoic peritidal environments facilitated through interactions among organic matter, cations, and silica. Organic matter from Proterozoic peritidal environments is not preserved by micro- or cryptocrystalline quartz alone. Rather, preservation includes cation-rich nanoscopic phases containing magnesium, calcium, silica, and aluminum that pre-date chert emplacement and may provide nucleation sites for silica deposition and enable further chert development. Using scanning electron microscopy and elemental mapping with energy dispersive X-ray spectroscopy, we identify cation enrichment in Proterozoic organic matter and cation-rich nanoscopic phases that pre-date chert. We pair these analyses with precipitation experiments to investigate the role of cations in the precipitation of silica from seawater. Our findings suggest that organic preservation in peritidal environments required rapid formation of nanoscopic mineral phases through the interactions of organic matter with seawater. These organic-cation interactions likely laid the initial foundation for the preservation and entombment of biosignatures, paving the way for the development of the fossiliferous chert that now contains these biosignatures and preserves a record of Proterozoic life.

The carapace and plastron bones of fossil turtles are often characterized by bone modification features such as pits, grooves, and holes. The significance, origin, and frequency of these features remains unclear because they have not been described from the bones of modern turtles. Taxon-specific description and analyses of defleshed turtle shell is essential for assessing the paleoecological significance of bone modification features. This study focuses on bone modification features on carapace and plastron bones of the emydid turtle Trachemys scripta elegans. Four subadult and 14 adult turtle shells were examined for non-ontogenetic features such as pits, grooves, holes, wounds, abrasions, and pathological growth structures. Bone modification features were lacking on subadult specimens but observed on each adult. Shallow, circular to subcircular pits (similar to the ichnotaxon Karethraichnus lakkos), and to a lesser extent pit clusters, are the most common feature noted on T. scripta elegans shells. Although they occur on both the plastron and the carapace, they proved far more common on the lower shell. Sparsely distributed ring-shaped grooves similar to the ichnotaxon Thatchtelithichnus holmani were present on approximately half of the turtle plastra studied. Amorphous surface etching was observed on several turtles, most commonly near the plastron midline (posterior portion of the hyoplastron/anterior portion of the hypoplastron). Pathological responses to these marks are lacking, but were noted on two turtles in response to sustained injuries. The occurrence of circular and subcircular pits, pit clusters, and ring traces on the external surface of every adult turtle analyzed in this study (regardless of sex or geographical occurrence), their discrete size and shape, and the lack of evidence of a systemic pathological response by the host suggests parasites, possibly leeches, as the etiological agent responsible for these features.

A new bioclaustration of a symbiont is here described from the mantle cavity of the strophomenatan brachiopod Clitambonites schmidti. It is the second bioclaustration in brachiopods known from the Kukruse Regional Stage (Sandbian) of Estonia. It shares affinities with the bioclaustrations Burrinjuckia and Haplorygma. The outgrowth in the ventral valve interior was secreted by the brachiopod around a symbiont. Most likely the symbiont was a suspension feeder that collected food particles from the brachiopod's mantle cavity. The symbiont was either a kleptoparasite or fed on the brachiopod's feces (coprophagy). The majority of symbiosis cases in brachiopods in the Ordovician of Baltica involve clitambonitids as the hosts. Thus, clitambonitid brachiopods were more likely hosts for symbiosis than other brachiopods in the Ordovician of Baltica.

The earwigs, Dermaptera, are a group of insects which have been present since the Mesozoic. They have a relatively sparse fossil record, yet their life activities on and in soil or sediment leave traces with the potential for long-term preservation. These may include some burrows seen in Quaternary dunes and other sandy substrates. The well-known, cosmopolitan, sand-dwelling species Labidura riparia is examined as a potential model and reference for dermapteran tracemakers there and elsewhere in the geological record, through experimentally produced shelter burrows and trackways from wild-caught, laboratory-raised specimens. Shelter burrows were typically U-shaped with a pair of surface entrances, and these U-shapes could be additionally modified into Y-shapes or linked together to form a network. Trackways of L. riparia generally resembled those of other insects but may show features consistent with dermapteran anatomy such as tail-drag impressions produced by cerci.

Skeletobionts, organisms that attach to or bore into the skeleton of a host, provide a useful system to observe biological interactions over geological timescales. We examined skeletobionts on brachiopod hosts from a stratigraphic section in western New York State that spanned the Lower Kellwasser and Upper Kellwasser events, the two pulses of the Frasnian–Famennian (Late Devonian) mass extinction. The fossils are largely preserved as molds, and even endoskeletobiont borings are often visible with minimal preparation. At least seven major groups of skeletobiont are present including microconchids, stenolaemate and ctenostome bryozoans, hederelloids, and various borings attributed to sponges. The total frequency of skeletobiosis declined significantly across the first extinction pulse (Lower Kellwasser Event), and relative abundance patterns shifted, although the biotic and/or abiotic drivers of these changes require further study. Multivariable logistic regression indicates that large host body size was a strong and consistent predictor of skeletobiosis. Endoskeletobionts were more common in coarser lithologies, reflecting either an ecological preference for sands over muds or a bias against preservation in mudstones. Endoskeletobionts were also more common on ribbed/costate host shells.