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<jats:title>ABSTRACT</jats:title> <jats:p>This study assesses the foraminiferal morphogroup concept as a quantitative tool for interpreting environments of deposition in the geological record. This was achieved by first establishing a solid paleoenvironmental framework based on assessment of trace fossils (Zoophycos, Cruziana, and Phycosiphon ichnofacies, and the unnamed brackish-water association), sedimentology, and facies analysis of shallow-marine siliciclastic units of the upper Albian Viking Formation of the Western Interior Seaway, Canada. Foraminiferal morphogroups were integrated into a framework of six well-defined marine mudstone-dominated facies—estuarine, embayment, prodelta, upper offshore, lower offshore, and marine shelf. Seven morphogroups were recognized, quantified, and labeled using alphanumeric codes—A (tubular), B1 (globular), B2 (coiled, flat), B3 (lenticular), C1 (elongate), C2 (quinqueloculine), and D (trochospiral).</jats:p> <jats:p>Tubular forms (A, Bathysiphon) occur rarely in these shallow-marine facies. Globular forms (B1, Lagenammina) are common in estuarine (33%) and embayment (23%) facies, but also occur elsewhere in low numbers (7–14%). Coiled planar forms (B2, Ammodiscus) occur only rarely (1–8%), but have a minor presence in embayment facies (8%). Lenticular forms (B3, Haplophragmoides) are dominant in estuarine facies (43%) and occur commonly in other environments (9–29%) as well. Elongate forms (C1, Ammobaculites, Reophax, Verneuilinoides) dominate all shallow-marine facies (43–80%), except estuarine (10%). Quinqueloculine forms (C2, Miliammina) have a minor presence in prodelta and marine facies (5%) but are generally rare. Trochoid forms (D, Trochammina) occur rarely, but are relatively common in the prodeltaic facies (15%). Albian foraminiferal morphogroups of the Viking Formation are comparable to those of modern-day offshore environments from water depths of 13 to 160 meters. Foraminiferal morphogroups are objective entities independent of taxonomic determinations. Analysis of their form and function is applicable not only in the shallow-marine facies of the Albian Western Interior Seaway, but in similar facies throughout the geologic record.</jats:p>

<jats:title>ABSTRACT</jats:title> <jats:p>A large collection of vertebrate coprolites derives from a debris flow conglomerate in the Upper Triassic Irohalene Member (Carnian) of the Timezgadiouine Formation, northern Argana Basin, Morocco. The coprolites are classified into 14 different morphotypes (MA to MN) based on their size, shape, and surface texture that are divided into three groups: striated coprolites; spiral and scroll-like coprolites; and non-spiral coprolites lacking striations. The great variety of morphotypes suggests the coprolites correspond to a variety of terrestrial and aquatic carnivorous producers. The carnivore coprolites lithified rapidly and were deposited in a high-energy sheetflood. The majority of the coprolites were produced by semi-aquatic and terrestrial tetrapods, with a small percentage produced by fish.</jats:p> <jats:p>The occurrence of Dicynodontocopros, common Alococopros, and some heteropolar forms with affinities to Heteropolacopros, are consistent with a late Carnian age for the Irohalene Member. The Irohalene coprolites are mostly similar to those of the coprofaunas of late Carnian age (Otischalkian–Adamanian) in the lower Chinle Group of the western United States in the co-occurrence of Alococopros and Dicynodontocopros. Significantly, this Moroccan coprofauna from Gondwana has close Laurussian relationships.</jats:p>

<jats:title>ABSTRACT</jats:title> <jats:p>Taphonomic indicators are often used to assess time-since-death of skeletal remains. These indicators frequently have limited accuracy, resulting in the reliance of other methodologies to age remains. Arctica islandica, commonly known as the ocean quahog, is a relatively widespread bivalve in the North Atlantic, with an extended lifespan that often exceeds two hundred years; hence, their shells are often studied to evaluate climate change over time. This report evaluates taphonomic age using 117 A. islandica shells collected from the Mid-Atlantic Bight offshore of the Delmarva Peninsula with radiocarbon dates extending from 60–4,400 cal years BP. These shells had varying degrees of taphonomic alteration produced by discoloration and degradation of periostracum. To determine if a relationship exists between taphonomic condition and time-since-death, radiocarbon ages were compared with the amount of remaining periostracum and type of discoloration. Old shells (individuals that died long ago) were discolored orange with no periostracum while younger shells (individuals that died more recently) had their original color, with some periostracum. Both the disappearance of periostracum and appearance of discoloration followed a logistic process, with 50% of shells devoid of periostracum and 50% discolored in about 1,000 years. The logistic form of long-term taphonomic processes degrading shell condition is first reported here, as are the longest time series for taphonomic processes in death assemblages within the Holocene record. This relationship can be utilized for triage when deciding what shells to age from time-averaged assemblages, permitting more efficient application of expensive methods of aging such as radiocarbon dating.</jats:p>

<jats:title>ABSTRACT</jats:title> <jats:p>Molluscan death assemblages occurring on present-day beaches frequently consist of secondary-colored shells, with yellow to brown and gray to black colors. It is hypothesized that this secondary coloration can be related to postmortem age and to conditions in the taphonomically active zone, altering shells to black and gray tones in reducing conditions, and then becoming yellowish or brownish in oxidizing settings. In this study, we assessed whether the variability in the degree of shell discoloration of two species of the infaunal bivalve Mactra collected in beach death assemblages from a temperate siliciclastic beach in Uruguay is a function of postmortem age, and whether this variability in discoloration can be linked to differences in their elemental composition, microstructure, and provenance. Although we did not detect any differences in mineralogy or elemental composition among shells differing in discoloration, we show that modern (younger than a century) beach shells are not secondary-colored, but have remained white, but some white shells are also old (millennial). In contrast, yellow and gray shells are consistently older than 1,000 years, indicating that this degree of discoloration requires millennial residence times in the taphonomically active zone and suggesting that discoloration can be used as an indicator of time averaging. Discolored shells are derived from subtidal death assemblages.</jats:p>

<jats:title>ABSTRACT</jats:title> <jats:p>Scorpions are intermediate predators in numerous terrestrial environments, and many are temporarily to permanently fossorial. As a result, they play key roles in terrestrial food webs, in soil development, and as ecosystem engineers. However, scorpions have a poorly described ichnofossil record likely due to an inadequate understanding of their trace morphology. Critical to correcting this is assessing the variability of burrows constructed by phylogenetically, geographically, and environmentally distinct scorpions. Five extant scorpions, Heterometrus spinifer, Pandinus imperator, Pandipalpus viatoris, Hadrurus arizonensis, and Paravaejovis spinigerus were studied through neoichnological experiments under varying substrate conditions. Burrow casts produced were described and compared across species and different substrate conditions. Tropical scorpions excavated sediment and carried it away from the burrow to produce open, straight-to-sinuous, subvertical tunnels to branching tunnel systems with single to multiple entrances and often chambers. Arid scorpions excavated with rapid leg movements to throw sediment behind the body to produce single to linked networks of U-shaped burrows as well as subvertical tunnels to tunnel networks with single to multiple entrances and rarely chambers. Changes in sediment composition and moisture tended to reduce burrow production but did not significantly alter burrow morphology. All scorpion burrows, regardless of species, bore a moderate-to-high similarity despite differences in excavation styles and architecture suggesting that scorpions produce burrows of consistent form regardless of phylogenetic or environmental distance. The result of these studies provides key ichnotaxobases of scorpion burrows which can be used to identify them in the fossil record and improve interpretations of ancient terrestrial ecosystems.</jats:p>

<jats:title>ABSTRACT</jats:title> <jats:p>Microbes colonize sediment and alter its properties creating a bio-mineral medium. The microbially induced sedimentary structures (MISS) are the fossil record of an interaction between the physical environment and such a medium. The present report documents bedding surface structures from the Cisuralian (Asselian) Sandstone Building Member (BSM) of the Słupiec Formation, a unit that outcrops in the south-western Poland, in the Sudetes Mountains. The BSM represents likely continental (fluvial) sedimentary settings. The sedimentary structures on bedding surfaces in the BSM are interpreted as the MISS. The observations of the bedding structures are supplemented with thin section data that support the microbial interpretation of the bedding surface structures. The Słupiec Formation MISS record supplements the global patchy fossil record of the post-Cambrian (Paleozoic) MISS from the non-marine settings.</jats:p>