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An array of trace fossils have been ascribed to brittle-star behaviors including locomotion traces such as Biformites. Brittle-star locomotion has been well described but little work has been done to link modern brittle-star behavior to the trace fossil record. To draw this connection, a brittle star was kept in an aquarium and isolated in a “walking” tank with a fine glass-bead substrate. The animal was left in the walking tank for 30 minutes then the substrate was examined for traces. A digital camera was used to record the animal's movements and to document the resulting traces. Photographs were processed with photogrammetry software to produce digital models in order to acquire high-resolution images. Walking traces were described in detail and two morphologies were identified, which correspond with the ‘rowing' and ‘reverse-rowing' modes of brittle-star locomotion. Interestingly, traces similar to Biformites were not formed although some Biformites characters are observed. Morphological similarities include elongated lobate depressions and bioglyphs. Trackway dissimilarities include a repeating, paired, symmetrical pattern observed in the lab contrasting with Biformites that is often expressed as a texture of dense and overlapping, or isolated imprints. Another dissimilarity is the expression of bioglyphs in the lab as striae compared to the positive protuberances observed in Biformites. This study illustrates the utility of using actualistic observations to: (1) refine interpretations of locomotory mechanisms, such as rowing and reverse rowing, for a better understanding of walking behavior, and (2) to expand recognition criteria for ophiuroid (and other taxa) tracks in the fossil record.

Low-level drone photogrammetry is a technique that allows for the construction of surface orthomosaics and elevation models. Despite being used for a wide range of geological applications, these types of datasets have not yet been explored from a neoichnological perspective. This study uses three examples of tidal flats from the Bay of Fundy to demonstrate the usefulness of 3D photogrammetry in the collection of high-resolution neoichnological datasets. The first site is a bar top along the Petitcodiac River that is situated between a salt marsh and tidal channel margin. The second site, which is located along the Shepody River, represents a laterally accreting channel margin and thus has a relatively high relief. In contrast, the final site comprises a gently sloping tidal flat that is far from the influence of a major tidal channel. Spatial analysis of the shorebird tracks at each site was used to assess the relationship between shorebird track distributions (e.g., track density, stride orientation, stride length) and various environmental and ecological factors (e.g., topography, tidal current direction, invertebrate prey distributions). Additionally, morphological analysis of the tracks was used to assess variations in substrate cohesiveness, which is the environmental factor that exhibited the most variability at the study locations. The track record at each site represents a shorebird flock that traversed the tidal flats in such a way as to optimize foraging success. As a result, the abundance and availability of macrobenthic invertebrate prey was the primary factor contributing to shorebird track density. This paper aims to assess local-scale variations in tidal flat substrate cohesiveness and provide context for the interpretation of fossilized shorebird trackways.

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.

The Kambaniru River valley near the city of Waingapu preserves a thick succession of coarse-grained fluvial-deltaic sediment deposited during the Late Pleistocene. This succession incises through a thick uplifted coral reef terrace succession and records intervals of highly episodic flow events during the last glacial interval. The occurrence of intraclastic, coarse sand/gravel matrix olistostromes in several areas attests to the occasionally catastrophic nature of flow in the ancestral Kambaniru River. Small to moderate-sized coral-rich reefs and laterally restricted reef terraces occur on delta-front conglomerate successions at multiple horizons through the study interval. These reefs record both intervals of low flow as well as periodic river-mouth avulsion episodes. Comparison of radiometric dates obtained from pelecypod and coral material from both deltaic successions and laterally adjacent coral reef terrace intervals indicates that uplift/subsidence history of the terraces differs from that of the valley and that correlation between the two should be taken with care.

Borings and bite marks on fossil turtle carapaces and plastra from the Miocene Moghra Formation, northern Egypt, are herein described. All fossil turtle material from Moghra exhibits ichnofossils. The positions of invertebrate borings on external surfaces of tortoise and turtle shell material at Moghra are consistent with the activities of ectoparasites or mesoparasites.A single invertebrate ichnotaxon, Karethraichnus lakkos Zonneveld et al., 2016, occurs on Moghra tortoise fossils. This trace fossil was likely emplaced by ixodid arthropods (ticks). Bite marks assigned to Nihilichnus occur on a carapace peripheral and are interpreted to reflect postmortem scavenging. An abundant and moderately diverse assemblage of invertebrate borings characterizes Moghra aquatic turtle shells. Karethraichnus lakkos and Thatchtelithichnus holmani Zonneveld et al., 2016 traces on aquatic turtles are interpreted to reflect leech and/or trematode parasitism. Gunnellichnus moghraensis (new ichnogenus new ichnospecies) and G. akolouthiste (n. isp.) likely reflect bacterial and/or fungal infections on aquatic turtle shells that rarely dried out.UUID: http://zoobank.org/f0a3977d-deff-4954-b196-536adc405854

A new wood-boring ichnospecies is described from transgressive (lagoonal) deposits of the Lower Cretaceous Sparky Formation (Mannville Group) in west-central Saskatchewan, Canada. Apectoichnus lignummasticans new ichnospecies is a trace fossil that occurs in a thin coal bed and that was emplaced in an in situ xylic substratum (woodground). The ichnofossil is thin, elongate, unbranched, and straight to gently curved with a circular cross section and uniform diameter. Apectoichnus lignummasticans n. isp. is similar in many respects to modern borings in wood that are produced by marine isopods, e.g., Limnoria lignorum Rathke, 1799, for feeding and refugia. The recognition of Apectoichnus lignummasticans n. isp. in the rock record aligns with the modern observation that fossilized wood-boring assemblages should display higher ichnofossil diversities than commonly reported. Additionally, the stratigraphic occurrence of Apectoichnus lignummasticans n. isp. in association with other evidence of marine deposition reaffirms that certain wood boring morphologies (i.e., ichnotaxa) are useful as indicators of marine transgressions.UUID: http://zoobank.org/880e722f-8944-42d7-bc38-423cc5a46413

Homo erectus is the founding early hominin species of Island Southeast Asia, and reached Java (Indonesia) more than 1.5 million years ago1,2. Twelve H. erectus calvaria (skull caps) and two tibiae (lower leg bones) were discovered from a bone bed located about 20 m above the Solo River at Ngandong (Central Java) between 1931 and 19333,4, and are of the youngest, most-advanced form of H. erectus5–8. Despite the importance of the Ngandong fossils, the relationship between the fossils, terrace fill and ages have been heavily debated9–14. Here, to resolve the age of the Ngandong evidence, we use Bayesian modelling of 52 radiometric age estimates to establish—to our knowledge—the first robust chronology at regional, valley and local scales. We used uranium-series dating of speleothems to constrain regional landscape evolution; luminescence, 40argon/39argon (40Ar/39Ar) and uranium-series dating to constrain the sequence of terrace evolution; and applied uranium-series and uranium series–electron-spin resonance (US–ESR) dating to non-human fossils to directly date our re-excavation of Ngandong5,15. We show that at least by 500 thousand years ago (ka) the Solo River was diverted into the Kendeng Hills, and that it formed the Solo terrace sequence between 316 and 31 ka and the Ngandong terrace between about 140 and 92 ka. Non-human fossils recovered during the re-excavation of Ngandong date to between 109 and 106 ka (uranium-series minimum)16 and 134 and 118 ka (US–ESR), with modelled ages of 117 to 108 thousand years (kyr) for the H. erectus bone bed, which accumulated during flood conditions3,17. These results negate the extreme ages that have been proposed for the site and solidify Ngandong as the last known occurrence of this long-lived species. Bayesian modelling of radiometric age estimates provides a robust chronology for Homo erectus at Ngandong (Java), confirming that this site currently represents the last known occurrence of this species.

The validity of the monotypic ichnogenus Thatchtelithichnus has been called into question due to an inference that it is a bioclaustration. Close analysis of the Thatchtelithichnus holmani holotype...

The Norian Stage is the longest stage in the Phanerozoic, and some members of the boundary working group have been evaluating suitable Carnian-Norian boundary sections for roughly two decades. This has identified two possible candidate boundary sections, at Black Bear Ridge (British Columbia, Canada) and Pizzo Mondello (Sicily, Italy). After a formal voting procedure within the working group, ending on the 26th July, 2021, the Pizzo Mondello section was selected as the global stratotype section and point for the base of the Norian. We evaluated the global correlation potential of the two proposed primary markers, the conodont Metapolygnathus parvus and the ‘flat-clam’ Halobia austriaca. Secondary markers were also evaluated around these boundary datums for correlation potential, and the veracity of the proposed sections for GSSP status. Data and arguments for the proposed sections and datums are presented here. Through a two-stage process of option elimination in voting, conforming with ICS guidelines, the working group decided by 60% majority to propose that the first occurrence datum of Halobia austriaca in the Pizzo Mondello section at the base of bed FNP135A should become the ‘golden spike’ for the base of the Norian. A secondary biotic marker for this boundary is the first occurrence of Primatella (Carnepigondolella) gulloae, in sample NA43, ca. 0 m below FNP135A, and the FA of Dimorphites noricus (sample NA42.1) ca. 3.5 m above bed FNP135 (indicating the first subzone of the Jandianus Zone). The best physical secondary marker is the magnetozone PM5n with the proposed boundary ca.40% through the thickness of PM5n. Strengths of the chosen datum are: 1) it also maintains historical priority for ammonoid zonations, which had placed the base Norian near to this level in Europe, North America and probably NE Asia; 2) Halobia austriaca is widely distributed in all paleolatitudes and is a long-established taxon.

The Upper Triassic (Carnian) Charlie Lake Formation in northeastern British Columbia, Canada is a heterolithic mixed siliciclastic-carbonate succession of dolomite dolomitic siltstone, well-sorted sandstone, bioclastic sandstone, and anhydrite. This succession is unusual in that it records the only significant non-marine interval in the Triassic of the Western Canadian Sedimentary Basin. In the Kobes-Altares-Blueberry area, moderately abundant core are available through the middle members of the Charlie Lake Formation. All available core were analyzed in order to interpret the depositional setting of constituent members and identify reservoir quality lithofacies and horizons. The middle Charlie Lake Formation in the Kobes-Altares-Blueberry area was deposited in an arid coastal setting. Sixteen lithofacies were identified and placed in three lithofacies assemblages and the latter characterize three depositional settings: coastal salina/playa, aeolian dune, and proximal marine ramps. The coastal salina/playa lithofacies assemblage is heterolithic, and is dominated by dolomitic and anhydritic facies. Depositional subenvironments include intertidal flat, ephemeral lagoon, shore proximal ephemeral lake, sabkha and supratidal paleosol. Potential reservoir lithofacies in this assemblage includes peloidal to stromatolitic dolomitic siltstone deposited in lagoonal and intertidal flat settings. The aeolian dune lithofacies assemblage preserves the movement of small, shore-proximal dunes and associated interdune successions. Well-sorted, fine-grained sandstone beds comprise the best reservoir lithofacies in this assemblage. The proximal marine ramp facies assemblage records several marine transgressions that punctuate the dominantly nonmarine/marginal marine Charlie Lake Formation. Bioclastic packstone, bioclastic sandstone and peloidal dolomitic siltstone to sandstone beds, all exhibit good porosity and are potential hydrocarbon reservoir units within this lithofacies assemblage.

International audience; This study focuses on the Lower–Middle Triassic Montney, Sunset Prairie, Doig and Halfway formations from the foreland basin of the Canadian Cordillera (Alberta and British Columbia). Based on core and outcrop descriptions, the correlation of 400 wells, and on mineralogical analyses, this study interprets the basin-scale, 3D-stratigraphic architecture of these formations and discusses the controls on its evolution.Well correlation highlights four sequences (1–4) interpreted to occur in two second-order cycles (A and B). In this work, the Early Triassic Montney Formation and the early Middle Triassic Sunset Prairie Formation are interpreted to consist of three third-order sequences (1–3) related to the first second-order cycle (cycle A). The Middle Triassic Doig and Halfway formations are interpreted to consist of a fourth sequence (4) related to a second second-order cycle (cycle B). Integration of the stratigraphic surfaces with previously published biostratigraphic analyses emphasizes a major time gap of c. 2 myr between these two cycles, interpreted to record a major reorganization of the basin. Mineralogical analyses suggest that during cycle A, sediments were delivered from the east (Canadian Shield); whereas in cycle B, additional sources from the west (proto-Canadian Cordillera) occurred. This study shows that the stratigraphic architecture evolution was affected by the structural heritage of the basin and continental geodynamic evolution. This study provides a large-scale understanding on the controls of the stratigraphic architecture of the Lower and Middle Triassic strata, suggesting local and regional controls on the reservoir extension and unconventional play configuration within these strata.

The end-Triassic mass extinction (ETE) is associated with a rise in CO2 due to eruptions of the Central Atlantic Magmatic Province (CAMP), and had a particularly dramatic effect on the Modern Fauna, so an understanding of the conditions that led to the ETE has relevance to current rising CO2 levels. Here, we report multiple phosphorite deposits in strata that immediately precede the ETE at Williston Lake, Canada, which allow the paleoenvironmental conditions leading up to the mass extinction to be investigated. The predominance of phosphatic coated grains within phoshorites indicates reworking in shallow water environments. Raman spectroscopy reveals that the phosphorites contain organic carbon, and petrographic and scanning electron microscopic analyses reveal that the phosphorites contain putative microfossils, potentially suggesting microbial involvement in a direct or indirect way. Thus, we favor a mechanism of phosphogenesis that involves microbial polyphosphate metabolism in which phosphatic deposits typically form at the interface of euxinic/anoxic and oxic conditions. When combined with data from deeper water deposits (Kennecott Point) far to the southwest, it would appear a very broad area of northeastern Panthalassa experienced anoxic to euxinic bottom water conditions in the direct lead up to the end-Triassic mass extinction. Such a scenario implies expansion and shallowing of the oxygen minimum zone across a very broad area of northeastern Panthalassa, which potentially created a stressful environment for benthic metazoan communities. Studies of the pre-extinction interval from different sites across the globe are required to resolve the chronology and spatial distribution of processes that governed before the major environmental collapse that caused the ETE. Results from this study demonstrate that fluctuating anoxic and euxinic conditions could have been potentially responsible for reduced ecosystem stability before the onset of CAMP volcanism, at least at the regional scale.

The reservoir quality of the Lower Triassic (Induan-Olenekian) Montney Formation of the Puskwaskau Field is assessed from two cored intervals. Four lithofacies are identified in the present study: these are defined by their detailed sedimentological characteristics. Lithofacies 1 (L-1) is composed of interlaminated bituminous very fine-to medium-grained siltstone and dolomitic medium-to coarse-grained siltstone. Lithofacies 2 (L-2) consists of interbedded dolomitic medium-to coarse-grained siltstone and bituminous very fine-to medium-grained siltstone. Lithofacies 3 (L-3) is dominated by bitumen-stained dolomitic medium-to coarse-grained siltstone. Lithofacies 4 (L-4) is characterized by dense, dolomitic coarse-grained siltstone to very fine-grained sandstone. Sediments within the study area are interpreted to have been deposited within a wave-to storm-influenced shoreface and offshore transition zone, comprising conformable progradational successions. The reservoir quality of these deposits is evaluated by comparing reservoir characteristics of each lithofacies. Analyzed properties include porosity, permeability, pore throat radius, clay content and cementation. Winland plots are used to show the predicted pore-throat diameters of lithofacies based on measured permeability (to air). The reservoir quality of L-1 is poor, with pore-throat radii ranging from 0.10 to 0.45 μm (micropores). The reservoir quality of L-2 is considered fair, with pore-throat radii ranging from 0.11 to 0.94 μm (micro- and mesopores). L-3 has the best reservoir quality in this study, with pore-throat radii ranging from 0.20 to 3.01 μm (mesopores). The reservoir quality of L-4 is considered poor due to pervasive dolomite cementation. Pore-throat radii for L-4 range from 0.17 to 0.25 μm (micropores). The range of values observed within each lithofacies effectively constrains the reservoir characteristics and demonstrate the correspondence of lithofacies classification to reservoir quality in this producing field.

Organic-rich, fine-grained sedimentary rocks, such as black shales, are important geochemical archives providing information on the evolution of seawater composition and biological activity over the past 3 billion years. While biological productivity and sedimentation rates greatly affect the organic matter content in these rocks, mechanisms linking these two processes remain poorly resolved. Here, we examine the interactions of clay minerals with the marine planktonic cyanobacterium Synechococcus sp. PCC 7002. We suggest that clays settling through the water column could influence carbon and trace metal burial in three ways: (1) the interaction of reactive clay surfaces with the bacterial cells increases organic matter deposition via mass increase in a seawater growth medium by several orders of magnitude; (2) reactive bacterial cells become completely encased within a clay shroud, enhancing the preservation potential of this organic matter; and (3) the trace metal content of the biomass buried along with metals sorbed to the clay particles contributes to the trace metal concentrations of the black shale precursor sediments. Significantly, our findings imply that the chemical composition of ancient, organic-rich, fine-grained deposits are not only archives of ancient seawater composition and redox state, but they also provide a record of the degree of biological activity in the water column through geological time.

Fine-grained sediment deposition is often conceived to happen in still water conditions and to represent slow sedimentation rates. However, it has been increasingly noted that mud sedimentation commonly occurs under high-energy conditions. The macrotidal Petitcodiac River estuary is used as an example to investigate the significance of flocculation as an important process in the rapid removal of large amounts of sediments from suspension under turbulent flow conditions. A range of physical sedimentary structures was observed at the Petitcodiac River estuary intertidal flats and bars, including low-angle and horizontal planar lamination, current and climbing ripples, surficial fluid mud, soft-sediment deformation, microfaults, and mud rip-up clasts. Fluid mud within the study area contains considerable proportions of clay (21–67%) and contributes to the formation of creeping fluid-mud sheets and streams. Detailed examination of the naturally occurring clay flocs shows that they contain up to 77% of the entangled silt- and sand-sized grains. SEM and microscopic imaging of fluid mud reveal a substantial amount of bioclastic material within the flocs and dispersed among the sediments. These observations show that physicochemical and biological processes influence silt, plankton, and clay aggregation. Water samples and observations from the Petitcodiac River estuary confirm that flocs form in the water column and then settle to the tidal-channel floor and flanking intertidal flats. Laboratory experiments, using Petitcodiac sediment, show how the clay flocs have the potential to sweep the water of silt-sized suspended grains. Additionally, diatoms and their associated extracellular polymeric substance (EPS) sheaths might play a role in mineral aggregation and increased sediment cohesiveness.

In this paper we examine quantitative ichnological data of silty-mudstone beds from inclined heterolithic stratification (IHS) in order to understand the spatial and temporal controls affecting bioturbation in IHS. Data collected for this study include bed-scale averaged bioturbation intensity, size-diversity index, and ichnogenera abundances. These data were used to assign each bed into one of 10 clusters using K-Means clustering. The clusters were ranked according to interpreted intensity of cumulative depositional ecologic stress. Time-series, where each silty-mudstone bed represents a time-step with a corresponding ecologic stress value, were constructed from the interpreted ecologic stress cluster analysis results. To identify and interpret spatial and temporal variation in the ichnological time-series, two time-series analysis methods were employed: dynamic time-warping and continuous wavelet transforms. Dynamic time-warping is used as a descriptor of the spatial similarity between ecologic stresses, and continuous wavelet transforms are used to interpret cyclical patterns in the ichnological time-series. Spatially, the variability and cyclicity observed in the ecologic stress time-series can be linked to estuary scale stresses and more localized stresses (i.e., bar-form scale depositional stress). This is reflected by the relatively similar periodicities observed in the ecologic stress time-series. Temporally, cyclical ecologic stress patterns occur somewhat predictably in periods of approximately four, or multiples of four, which are consistent with El Nino cyclicity.

Collecting and analyzing semi-quantitative ichnological parameters such as size-diversity index and bioturbation intensity, can increase the resolution of paleoenvironmental analyses. Specialized software, PyCHNO, was designed to ease, improve, and standardize current ichnological data collection techniques. With PyCHNO, ichnological data derived from burrow diameter measurements, trace fossil identification (ichnogenus level), and bioturbation index are collected at a user-defined scale, and size-diversity index is calculated from these measurements. Data collected in PyCHNO, including size-diversity index, maximum burrow diameter, trace fossil diversity, trace fossil taxon abundance, and bioturbation index is easily exported as text files or plotted as PDF logs.

Fieldwork conducted in the Wasatch Formation in and around Fossil Butte has yielded a diverse assemblage of early Eocene vertebrates. Fossil vertebrates are distributed through three discrete stratigraphic intervals within the uppermost 180 m of the main body of the Wasatch Formation underlying the Green River Formation. These assemblages were derived primarily from fluvial overbank mudstone units overprinted with variably well-developed paleosols. The lowest (20 m) and highest (60 m) sections are characterized by less mature and more hydromorphic paleosols, whereas the middle section (100 m) is typified by more mature paleosols and more abundant channel sandstones.The combined assemblages contain at least 46 species of mammals. Faunal characteristics include high abundances of equid perissodactyls and a relatively high abundance and diversity of notharctines primates, an apparent absence of omomyid primates, relatively high rodent diversity, and relatively diverse and abundant artiodactyls. One new genus (Eoictopsnew genus) and three new species (Eoictops novacekinew species,Palaeosinopa lacusnew species, and ?Notoparamys blochinew species) are included in the Fossil Butte assemblage. Also recorded are late occurrences of two hyopsodontid condylarths and an early occurrence of a rare phenacodontid condylarth. The relatively high abundances of equids and notharctines suggest that vertebrate samples were derived from relatively open paleohabitats that included forested areas along water courses.All three assemblages contain characteristic Lysitean (Wasatchian biochron Wa-6) elements, but the occurrence of the palaeotheriid perissodactylLambdotheriumin the uppermost horizon indicates a Lostcabinian (Wa-7) age for at least the top of the Wasatch Formation. The overlying predominantly fish-bearing Fossil Butte Member of the Green River Formation also containsLambdotheriumand is therefore Wa-7 in age as well.

New isotopic ages have been obtained from euhedral, first-cycle zircon grains recovered from Rhaetian strata preserved at the Black Bear Ridge section in northeastern British Columbia. Two statistically significant populations are present: an older population ca. 224 Ma, and a dominant younger population ca. 205 Ma. The younger population includes a group of grains with a weighted average 206 Pb/ 238 U age of 205.2 ± 0.9 Ma, which is interpreted to represent the maximum depositional age of the sediment. Potential sources for the two populations are found in the Quesnel terrane in central British Columbia, implying close proximity between this terrane and the autoch­thonous North American margin during the Late Triassic. This is supported by geochemical and structural evidence. The implication that the Quesnel terrane was close to its present-day latitude during the Late Triassic is in conflict with older estimates of paleolatitude based on paleomagnetic and paleontological evidence. The age of 205.2 ± 0.9 Ma obtained from the youngest population of zircons is also consistent with recently published estimates for the age of the Norian-Rhaetian boundary.

Detailed outcrop analysis of an Upper Triassic, shallow marine, mixed siliciclastic–carbonate ramp succession in northwestern Canada reveals numerous disconformities that are characterized by substrate-controlled trace-fossil assemblages. Although Glossifungites assemblages, and to a lesser extent, Trypanites assemblages, are common in the Upper Carnian Baldonnel Formation, in several horizons, a pattern of paired Trypanites–Glossifungites-demarcated discontinuity surfaces occurs. These paired surfaces occur in the same overall environmental setting and are interpreted to have the same general stratigraphic implications in each case. The Trypanites surfaces invariably occur lower in the section. They penetrate into sandy bioclastic limestone and are infilled and overlain by a coarse-grained detrital lag. Their development indicates early cementation in a coastal setting. The Trypanites surfaces form coplanar maximum regressive surfaces and transgressive surfaces of erosion and are correlatable on a regional scale. The lags are overlain, in turn, by laminated calcareous siltstone (denoting offshore deposition) and bioclastic sandstone (a return to shoreface depositional conditions). The siltstone–sandstone contacts are characterized by low-diversity Glossifungites assemblages, which are interpreted as an amalgamated succession of storm-induced wave ravinement surfaces emplaced in front of a rapidly prograding shoreface. Paired Trypanites–Glossifungites surfaces in the Baldonnel Formation reflect fluctuations in relative sea level and sediment input in an overall low accommodation mixed siliciclastic–carbonate ramp setting.

It is semi-traditional at PALAIOS for the outgoing editor to provide a Spotlight article as their tenure as editor ends. Past editors have pontificated on the state of the journal, its ranking, and its path to the future (e.g., Hasiotis and Taylor 2010; Hasiotis and Zonneveld 2012; Hasiotis 2013). In truth, I have a very positive outlook for the journal. PALAIOS is strong and healthy and I leave it in the capable hands of co-editors Gabriella Mangano and Thomas Olszewski and managing editor Kathleen Huber; three amazing human beings, each of whom possesses a wiser head than my own. PALAIOS has a very optimistic future with editors like these at the helm! To quote present and former Prime Ministers of Canada, “Sunny ways, my friends, sunny ways” (Laurier 1895; Trudeau 2015). Before I segue to my main topic, however, I wish to digress on some acknowledgements that are indeed in order. First and foremost I'd like to thank my co-editors Stephan Hasiotis and Thomas Olszewski. I learned much from both of you and it was indeed an honor to serve our society in the capacity of editor. I will always be grateful to Jill Hardesty, PALAIOS managing editor for my first few years as editor. Jill passed away last year but left a permanent imprint on the journal that we both love. Jill was succeeded by Kathleen Huber, our present managing editor, who quietly and capably piloted PALAIOS through a very difficult interval. Thank you Kathleen! I am also forever grateful to Melissa Lester and the Journal of Sedimentary Research who loaned us Melissa to help get PALAIOS through the difficult interval after Jill had to step down. The PALAIOS readership is also well served by a large group of generally unsung heroes, our associate editors. Without …

The study provides a detailed description of mud-dominated sedimentary fabrics and their application for the rock record within the inner estuary to the fluvial zone of the Petitcodiac River estuary, New Brunswick, Canada. Sedimentological characteristics and facies distributions of the clay- and silt-rich deposits are reported. The inner estuary is characterized by thick accumulations of interbedded silt and silty clay on intertidal banks that flank the tidally influenced channel. The most common sedimentary structures observed are parallel and wavy lamination, small-scale soft-sediment deformation with microfaults, and clay and silt current ripples. The tidal channel contains sandy silt and clayey silt with planar lamination, massive and convolute bedding. The fluvio-tidal transition zone is represented by interbedded trough cross-stratified sand and gravel beds with planar laminated to massive silty mud. The riverine, non-tidal reach of the estuary is characterized by massive, planar tabular and trough cross-stratified gravel-bed deposits. The absence of bioturbation within the inner estuary to the fluvio-tidal transition zone can be explained by the following factors: low water salinities (0–5 ppt), amplified tide and current speeds, and high concentrations of flocculated material in the water body. Notably, downstream in the middle and outer estuary, bioturbation is seasonally pervasive: in those locales the sedimentary conditions are similar, but salinity is higher. In this study, the sedimentological (i.e., grain size, bedding characters, sedimentary structures) differences between the tidal estuary and the fluvial setting are substantial, and those changes occur over only a few hundred meters. This suggests that the widely used concept of an extensive fluvio-tidal transition zone and its depositional character may not be a geographically significant component of fluvial or estuary deposits, which can go unnoticed in the study of the ancient rocks.

Triassic rocks of the Western Canada Sedimentary Basin (WCSB) have previously been interpreted as being deposited on the passive margin of North America. Recent detrital zircon provenance studies on equivalent Triassic rocks in the Yukon have suggested that these rocks were in part derived from the pericratonic Yukon–Tanana terrane and were deposited in a foreland basin related to the Late Permian Klondike orogeny. Detrital zircons within a number of samples collected from Triassic sediments of the WCSB throughout northeastern British Columbia and western Alberta suggest that the bulk of the sediment was derived from recycled sediments of the miogeocline along western North America, with a smaller but significant proportion coming from the Innuitian orogenic wedge in the Arctic and from local plutonic and volcanic rocks. There is also evidence of sediment being derived from the Yukon–Tanana terrane, supporting the model of terrane accretion occurring prior to the Triassic. The age distribution of detrital zircons from the WCSB in British Columbia is similar to those of the Selwyn and Earn sub-basins in the Yukon and is in agreement with previous observations that sediment deposited along the margin of North America during the Triassic was derived from similar source areas. Together these findings support the model of deposition within a foreland basin, similar to the one inferred in the Yukon. Only a small proportion of zircon derived from the Yukon–Tanana terrane is present within Triassic strata in northeastern British Columbia, which may be due to post-Triassic erosion of the rocks containing these zircons.

The paleoecology of rocky substrates in the rock record is commonly interpreted based on ichnology and is frequently associated with a bioeroding community (the Trypanites Ichnofacies) with low ichnological diversity. However, analyses of a modern, siliciclastic, intertidal hardground community at Lion Rock, located at Arcadia Beach State Park, Oregon, reveals a diverse community of boring, encrusting, and squatting/clinging organisms. Through observations and descriptions of organism distribution and abundance, more than 40 species of plants and animals are reported to reside within three littoral zones (upper, middle, and lower littoral zone) on the sea stack. A newly established erosional lower littoral zone is a subdivision of the lower littoral zone, where shifting foreshore sand influences colonization and biotic diversity. Borings are produced by four bivalves, Adula californiensis, Hiatella arctica, Penitella penita, and Zirfaea pilsbryi, and are identified as Gastrochaenolites traces. It ...

The mechanisms underpinning the deposition of fine-grained, organic-rich sediments are still largely debated. Specifically, the impact of the interaction of clay particles with reactive, planktonic cyanobacterial cells to the sedimentary record is under studied. This interaction is a potentially major contributor to shale depositional models. Within a lab setting, the flocculation and sedimentation rates of these materials can be examined and measured in a controlled environment. Here, we detail a protocol for measuring the sedimentation rate of cyanobacterial/clay mixtures. This methodology is demonstrated through the description of two sample experiments: the first uses kaolin (a dehydrated form of kaolinite) and Synechococcus sp. PCC 7002 (a marine coccoid cyanobacteria), and the second uses kaolin and Synechocystis sp. PCC 6803 (a freshwater coccoid cyanobacteria). Cyanobacterial cultures are mixed with varying amounts of clay within a specially designed tank apparatus optimized to allow continuous, real-time video and photographic recording. The sampling procedures are detailed as well as a post-collection protocol for precise measurement of chlorophyll a from which the concentration of cyanobacterial cells remaining in suspension can be determined. Through experimental replication, a profile is constructed that displays sedimentation rate.

Stratigraphic correlation of fine-grained successions is not always straightforward. Complicating factors such as unconformities, structural complexity, subsidence, and especially minimal grain-size variation, make the application of traditional correlation methods to fine-grained successions problematic. Alternatively, the analysis of detailed geochemical data can allow for the determination of variations in sediment provenance, mineralogy, detrital flux and hydrothermal input. When compared with modelled clay input over time, these geochemical indicators can be used to determine changes in relative sea-level and palaeoclimate, allowing for the identification of clinoform surfaces. As an example, this study outlines detailed correlations of chemostratigraphic packages within the lower Triassic Montney Formation in western Canada to demonstrate the effectiveness of chemostratigraphy in defining and correlating fine-grained clinoforms across a sedimentary basin. The data set used includes five wells and one outcrop succession, from which geochemical profiles were generated and tied directly to mineralogical data and well logs. These analyses reveal 13 distinct chemostratigraphic packages that correlate across the basin. Observed elemental and inferred mineralogical changes highlight trends in relative sea-level and palaeoclimate, as well as episodes of inferred hydrothermal input to the Montney basin. Cross-plots of La/Sm and Yb/Sm further suggest hydrothermal input as well as the scavenging of middle rare earth elements by phosphatic fish debris. Additionally, plots of La/Sm versus Yb/Sm, which show volcanic arc input within the Doig Formation, suggest an additional sediment source from the west during the Anisian. Pairing detrital and clay proxies demonstrates changes in relative sea-level and, at the Smithian/Spathian boundary, the lowest relative sea-level in the Montney Formation is observed, corresponding to a change in climate. This article is protected by copyright. All rights reserved.

Late Triassic (Carnian–Norian) echinoids from the Aksala Formation in the Lake Laberge area of the Whitehorse Trough, Yukon Territory, Canada, are described. These echinoids comprise the first description of Triassic echinoids from Canada and, with the exception of fragmentary material from Utah, are the only Upper Triassic echinoids on the western coast of Pangaea north of Peru. Triassicidaris peruviensis Smith is identified from a coronal fragment that consists of an ambulacral column and five attached interambulacral plates from a Carnian outcrop succession. Parvicidaris sp., also from Carnian strata, is identified based on a coronal fragment that consists of two ambulacral and three interambulacral columns. This occurrence extends the range of this typically Norian taxon both north to the Yukon and earlier into the Carnian. Additional specimens, identified as Triassicidaris sp., occur within Norian strata of the Aksala taxa, one of which (‘Cidaris’ labergensis sp. nov.) is new. Both the corona-based taxa and the spine form taxa show mixed affinities with Tethyan and southern New World populations and reinforce the association between Triassic echinoid faunas and reefal settings.

A stratified paleosol sequence exposed in an open pit mine in central Sumatra provides a record of the paleoenvironmental conditions in the lower reaches of a large river system in the late Paleogene (latest Eocene or Oligocene). Morphological, geochemical, and stable isotope data suggest that the sequence represents a mosaic of local environmental conditions changing from estuarine to riverine up section. Weakly expressed soils formed on low-lying estuary surfaces, while more well expressed soils formed on higher, better drained surfaces. Peatlands (coal) with clayey subsoils were along the estuary margins. Well-expressed soils with evidence of clay translocation and chemical weathering become more common higher in the section where alluvial deposits associated with a meandering river are dominant. Stable carbon isotope ratios support a paleolandscape dominated by C 3 plants with input by C 4 vegetation limited to a few intervals. Finally, whole-rock geochemistry suggests moderate chemical weathering consistent with a tropical locality. This multi-proxy paleoenvironmental reconstruction suggests a highly productive lowland forest environment at this locality in the late Paleogene and provides the first direct examination of the terrestrial environment in Sumatra at this time. The limited fossil record in Island Southeast Asia during this time period is likely a result of poor bone and shell preservation in tropical forest environments combined with a general lack of systematic prospecting. However, our continuing work in this area has produced a relatively diverse assemblage of fossil vertebrates, now including fishes, amphibians, turtles, crocodiles, and mammals, as well as a growing diversity of fossil plants.

Important palaeoecologic and stratigraphic information can be obtained by observing trace assemblages within various substrate types in a modern intertidal marine environment. Overall, there has been a lack of studies conducted concerning quantitative firmness measurements on firmground, stiffground and softground substrates in a modern intertidal setting, and the combined palaeoecological and stratigraphic significance of such substrates. This study assesses the sedimentologic and neoichnologic nature of associated peaty-clay firmground, silty-sand firmground, woodground, stiffground and softground substrates in Netarts Bay, Oregon, USA, to gain a more complete understanding of the potential palaeoecologic and stratigraphic utility of these substrates in an intertidal setting. A north–south-oriented transect was conducted along the eastern margin of Netarts Bay where descriptions of surface and sub-surface biogenic and sedimentary structures were conducted via trenching, boxcoring and epoxy resin casting with results recorded and photographed. A sample of 18 different organisms creating biogenic structures were obtained, stored in glass jars and preserved with an 80% ethyl alcohol solution. Quantitative substrate firmness measurements were conducted on four of the five different substrate types using a modified Brinell firmness test. In Netarts Bay, firmground substrates and associated trace assemblages displaying larger, more robust, vertical traces likely have a higher preservation potential compared with stiffground to softground substrates that have trace assemblages composed of smaller traces that tend to grade into a horizontal position. Firmground substrate in Netarts Bay display more homogenous and firmer profiles (1.28 × 106 Pa to 2.77 × 106 Pa) than those of more heterogeneous stiffground (1.37 × 105 Pa to 2.44 × 106 Pa) and softground (8.60 × 104 Pa to 3.73 × 105 Pa) substrate. The relatively planar Pleistocene-aged firmground substrates and associated in situ woodground substrates at Netarts Bay were found to be laterally extensive and mappable stratigraphically significant surfaces. This is in contrast to the highly variable, non-significant, erosionally derived stiffground and bay-derived softground substrates that are neither extensive nor mappable. Trace assemblages in the peaty-clay and silty-sand firmgrounds studied were representative of a Glossifungites ichnofacies assemblage while associated in situ woodground trace assemblages comprised localized Teredolites ichnofacies assemblages Firmground, Neoichnology, Netarts Bay, Glossifungites, Teredolites.

Borings in fossil turtle shells collected from the lowermost beds of the early Eocene Cathedral Bluffs Tongue of the Wasatch Formation in the northwestern part of the Green River Basin near South Pass, Wyoming, are herein described. Individual turtle shells in the study area are characterized by as few as one or two and as many as >100 borings. The borings include both non-penetrative forms (those which do not pass fully though the shell) as well as penetrative forms (those which pass fully from the exterior to the interior surface of the shell). All non-penetrative forms occur on external surfaces of the carapace and plastron (i.e. those that would have been accessible while the host taxon was alive). Two new ichnogenera and four new ichnospecies are established to describe these borings.Karethraichnus(new ichnogenus) includes three ichnospecies:K.lakkos(new ichnospecies),K.kulindros(new ichnospecies), andK.fiale(new ichnospecies).Karethraichnus lakkosare shallow (non-penetrating), hemispherical pits with rounded, to flattened bases.Karethraichnus kulindrosare deep, non-penetrative traces with a cylindrical profile, an axis approximately perpendicular to the substrate surface and with rounded to flattened, hemispherical termini.Karethraichnus fialeare penetrative traces with a cylindrical to bi-convex or flask-shaped profile, and an axis approximately perpendicular to the substrate surface.Thatchtelithichnus(new ichnogenus)Thatchtelithichnus holmani(new ichnospecies) consist of non-penetrative borings into a bone substrate. They consist of a ring-shaped trace, with a central pedestal or platform. The position of the borings on the shells, and evidence of syn-emplacement healing of the borings in several of the turtles, indicates that these borings were emplacement by ectoparasites/mesoparasites while the animals were living. Similar traces in modern emydid turtles are attributed to ticks, leeches, or spirorchid liver flukes.

The most conclusive evidence of tidal sedimentation consists of deposits that exhibit evidence of rhythmic sedimentation attributable to tidal cyclicity. Until now such deposits have been limited to physical sedimentary structures. Tubular tidalites, defined herein, are combined biogenic–physical sedimentary structures that provide compelling evidence for tidal mediation in sedimentary successions. These structures consist of rhythmically bedded alternating layers of fine-grained and coarse-grained laminae deposited within open framework burrows such as Arenicolites, Ophiomorpha, Palaeophycus, Psilonichnus, and Thalassinoides. Importantly, the open framework burrows represent natural sediment traps that potentially preserve depositional cycles that might be missing due to high levels of bioturbation in settings such as intertidal flats and lagoons. The interpretation of the burrow infills as being tidally modulated is tested and supported in three ways: using exponential smoothing of thickness data on burrow-infilling laminae to identify rhythmic trends in laminae thicknesses, visually fitting sinusoidal curves to the raw thickness distributions, and using Fast Fourier Transform analysis. Considering the morphology of tubular tidalites presented, the parameters that promote the occurrence of tubular tidalites include an open aperture, bimodal sediment availability, tidal influence in sedimentation, and low overall sedimentation rates. Tubular tidalites have been identified from tidally influenced successions in Mesozoic, Cenozoic, and modern deposits and provide evidence of tidal influence in sedimentary successions where other indicators may be ambiguous.

The Trypanites ichnofacies is frequently associated with low biotic and trace diversity, and erosional or nondepositional conditions. However, analysis of an extensively exposed, modern, siliciclastic, intertidal hardground community near Thomas Cove, located at Economy Point, Nova Scotia, within the Bay of Fundy, reveals a diverse community of boring, encrusting, and squatting/clinging organisms and a diverse assemblage of sedimentary structures. A high diversity of biota and low diversity, but high abundance, of borings is present along this modern Trypanites-type ichnofacies. Species richness reaches 37 organisms within the study area, and two boring bivalves (Petricola pholadiformis and Zirfaea pilsbryi), which produce Gastrochaenolites-like traces, are present. Eleven distinct depositional subenvironments are identified and are categorized as being either Trypanites-bearing or Trypanites-barren. Analysis of this modern analogue suggests that ancient Trypanites ichnofacies may have been more ...

Small round pits and holes in fossil skeletal material are found in a wide variety of invertebrate substrates from diverse environmental settings. They are associated with parasitism, predation and commensal attachment. Four ichnogenera have been proposed for these trace fossils: Sedilichnus Muller, Oichnus Bromley, Tremichnus Brett and Fossichnus Nielsen, Nielsen and Bromley. Previous authors have established that Tremichnus is a junior synonym of Oichnus. Herein we show that Oichnus and Fossichnus are junior synonyms of Sedilichnus. Sedilichnus, as defined herein, includes 10 ichnospecies. Sedilichnus spongiophilus, S. simplex, S. paraboloides, S. ovalis, S. coronatus, S. gradatus, S. halo, S. asperus, S. excavatus and S. solus. Consistent with previous work Sedilichnus ichnospecies are defined solely by morphological criteria and not by a priori assumptions regarding depositional environment or tracemaker. Thus, this ichnotaxon is recognized in both marine and continental settings on a wide variety of invertebrate skeletal tests. As is true with many ichnotaxa, Sedilichnus ichnospecies represent end-members in morphological spectra, however each ichnospecies is clearly differentiable from the others. Sedilichnus spongiophilus are circular, non-penetrative pits in shells. Sedilichnus paraboloides are penetrative holes with spherical paraboloid forms and typically have larger external openings and smaller internal openings. Sedilichnus simplex are simple cylindrical borings that have both penetrative and non-penetrative forms. Sedilichnus coronatus differ from other forms by the presence of an etched or granular halo surrounding the boring. Sedilichnus gradatus have two concentric parts, an outer boring and an inner shelf of smaller diameter. Sedilichnus ovalis and S. asperus are both oval in outline differing in the presence of tapering paraboloid margins in S. ovalis and margins perpendicular to the substrate in S. asperus. Sedilichnus excavatus and S. solus are primarily non-penetrative and differ from other Sedilichnus by the presence of central, raised bosses or platforms. These two ichnospecies differ in the shapes of their external walls and the proportional thickness of the bounding groove.

Small round pits and holes in fossil skeletal material are found in a wide variety of invertebrate substrates from diverse environmental settings. They are associated with parasitism, predation and commensal attachment. Four ichnogenera have been proposed for these trace fossils: Sedilichnus Müller, Oichnus Bromley, Tremichnus Brett and Fossichnus Nielsen, Nielsen and Bromley. Previous authors have established that Tremichnus is a junior synonym of Oichnus. Herein we show that Oichnus and Fossichnus are junior synonyms of Sedilichnus.Sedilichnus, as defined herein, includes 10 ichnospecies. Sedilichnus spongiophilus, S. simplex, S. paraboloides, S. ovalis, S. coronatus, S. gradatus, S. halo, S. asperus, S. excavatus and S. solus. Consistent with previous work Sedilichnus ichnospecies are defined solely by morphological criteria and not by a priori assumptions regarding depositional environment or tracemaker. Thus, this ichnotaxon is recognized in both marine and continental settings on a wide variety of invertebrate skeletal tests. As is true with many ichnotaxa, Sedilichnus ichnospecies represent end-members in morphological spectra, however each ichnospecies is clearly differentiable from the others.Sedilichnus spongiophilus are circular, non-penetrative pits in shells. Sedilichnus paraboloides are penetrative holes with spherical paraboloid forms and typically have larger external openings and smaller internal openings. Sedilichnus simplex are simple cylindrical borings that have both penetrative and non-penetrative forms. Sedilichnus coronatus differ from other forms by the presence of an etched or granular halo surrounding the boring. Sedilichnus gradatus have two concentric parts, an outer boring and an inner shelf of smaller diameter. Sedilichnus ovalis and S. asperus are both oval in outline differing in the presence of tapering paraboloid margins in S. ovalis and margins perpendicular to the substrate in S. asperus. Sedilichnus excavatus and S. solus are primarily non-penetrative and differ from other Sedilichnus by the presence of central, raised bosses or platforms. These two ichnospecies differ in the shapes of their external walls and the proportional thickness of the bounding groove.

Bivalves have pursued an infaunal lifestyle since early in their history. Trace fossils that have been attributed to the infaunal activity of bivalves include Hillichnus, Lockeia (=Pelecypodichnus), Lophoctenium, Protovirgularia, Ptychoplasma, Siphonichnus and Scalichnus. Re-evaluation of the ichnogenera Siphonichnus and Scalichnus supports consolidation into a single ichnogenus, Siphonichnus, which has taxonomic precedence.Siphonichnus, as redefined herein, presently includes four ichnospecies. Siphonichnus eccaensis Stanistreet et al. is an unlined vertical tube characterized by concave downward laminae penetrated by a single central shaft and is interpreted to reflect downward burrowing in response to net erosion during the life span of the animal. Siphonichnus phiale (Hanken et al., 2001) is characterized by concave upwards laminae and reflects equilibrichnial behavior by the tracemaker. Siphonichnus lepusaures n. isp. is characterized by concave upwards laminae with a pair of vertically oriented, unlined tubes at the top and is interpreted as the dwelling trace of a bivalve with paired siphons responding to sediment aggradation. Siphonichnus sursumdeorsum n. isp. is characterized by concave upwards laminae in its basal third and convex upwards laminae in its upper third and is interpreted as the dwelling trace of a bivalve exhibiting equilibrichnial behavior in a dynamic depositional setting. Consolidation of these ichnotaxa into a single ichnogenus simplifies the ichnotaxonomy and provides a means of assessing the sedimentological significance of bivalve-generated dwelling/equilibrium/escape structures.

The entire Late Jurassic–Early Cretaceous stratal package between the Fernie Formation and the Cadomin Formation, from Townships 62–74 in the subsurface of northwestern Alberta, is assigned to the Monteith Formation (Minnes Group). Three mappable units are present, informally termed Monteith A, B and C, from youngest to oldest. The Monteith C was deposited in a marginal marine–deltaic depositional setting. Upward, the transition to coastal plain (Monteith B) and fluvial (Monteith A) depositional settings records a continuous progradation of a long-lived depositional system. Mapping of these units is aided by identification of regionally extensive marine flooding surfaces in the Monteith C, which are used as stratigraphic datums. The thickness of the Monteith Formation decreases from 450 m in the southwestern portion of the study area to a zero-edge in the northeast. The Monteith A, B and C are up to 160 m, 100 m and 200 m thick, respectively. Depositional thinning to the northeast is prevalent, but the primary reason for gross stratal thinning is substantial incision associated with the overlying sub-Cadomin unconformity. The Monteith Formation in Alberta was deposited in a foredeep setting. Regional thickness trends suggest increased accommodation to the southwest and the strata are interpreted to have accumulated on the cratonward side of the foredeep axis. These observations, as well as evidence for basin axial channel flow to the northwest during deposition of the Monteith C, support an interpretation that the foreland basin had initiated prior to Monteith Formation deposition. Basin physiography, as well as uplift and denudation of the Cordillera, affected the depositional evolution of units in the study area. Ultimately, these factors strongly influenced the distribution of reservoir rocks (primarily sandstones of the Monteith A and C), which are part of the Deep Basin Gas System. The presence or absence of permeability enhancing fractures also impacts reservoir quality and well deliverability in the Monteith Formation.