During IODP Expedition 310 (Tahiti Sea Level), drowned Pleistocene–Holocene barrier-reef terraces were drilled on the slope of the volcanic island. The deglacial reef succession typically consists of a coral framework encrusted by coralline algae and later by microbialites; the latter make up ≤80% of the rock volume. Lipid biomarkers were analyzed in order to identify organisms involved in reef-microbialite formation at Tahiti, as the genesis of deglacial microbialites and the conditions favoring their formation are not fully understood. Sterols plus saturated and monounsaturated short-chain fatty acids predominantly derived from both marine primary producers (algae) and bacteria comprise 44 wt% of all lipids on average, whereas long-chain fatty acids and long-chain alcohols derived from higher land plants represent an average of only 24 wt%. Bacterially derived mono-O-alkyl glycerol ethers (MAGEs) and branched fatty acids (10-Me-C_16:0; iso- and anteiso-C_15:0 and -C_17:0) are exceptionally abundant in the microbial carbonates (average, 19 wt%) and represent biomarkers of intermediate-to-high specificity for sulfate-reducing bacteria. Both are relatively enriched in ¹³C compared to eukaryotic lipids. No lipid biomarkers indicative of cyanobacteria were preserved in the microbialites. The abundances of Al, Si, Fe, Mn, Ba, pyroxene, plagioclase, and magnetite reflect strong terrigenous influx with Tahitian basalt as the major source. Chemical weathering of the basalt most likely elevated nutrient levels in the reefs and this fertilization led to an increase in primary production and organic matter formation, boosting heterotrophic sulfate reduction. Based on the observed biomarker patterns, sulfate-reducing bacteria were apparently involved in the formation of microbialites in the coral reefs off Tahiti during the last deglaciation.

A large number of specimens (∼500) of the hyolithid Hallotheca cf. aclis (Hall) were collected from the Middle Devonian Arkona Shale at Hungry Hollow, Ontario, Canada. This is an unusually large sample for Devonian hyolithids and only the second record of hyolithids from the Michigan Basin. Furthermore, the conchs of seven specimens are bored, and the holes are single, complete, circular in plan view, and with their long axes perpendicular to the walls of the conch. These traits and the fact that the holes are stereotyped with respect to the side of the conch—all occur on the venter—are consistent with a predatory origin of the holes. Although bored specimens represent only ∼1% of the sample, this record expands the taxonomic breadth of bored prey during the middle Paleozoic, a time previously recognized as characterized by intensification of predator-prey interactions.

The Eocene Tallahatta Formation exposed in the eastern United States Gulf coastal plain includes enigmatic siliceous facies characterized by variably indurated claystone, porcelanite, and subordinate thin sandstone and siltstone beds. Ichnosedimentologic studies at localities in eastern Mississippi and Alabama indicate that these strata accumulated in middle-shelf settings (offshore transition). Sandstone and siltstone beds record storm events of variable magnitude. Moderately diverse Cruziana ichnofacies assemblages that reflect overall hospitable fair-weather conditions characterize most mudrock intervals; however, periodically oxygen-deficient or otherwise unfavorable conditions are indicated locally by unbioturbated mudrock. Storm beds associated with bioturbated mud typically contain mixed Cruziana-Skolithos ichnofacies assemblages reflecting the work of both opportunistic(?) and fair-weather tracemakers. In contrast, ichnofabrics of storm beds that were not disrupted by fair-weather bioturbation likely record short-term colonization of substrates by organisms that were transported, sorted, and redeposited by storm currents. Ichnofabrics and diagenesis of the siliceous facies are linked. Ichnofossils locally influenced silica cementation in some storm beds, whereas preferential conversion to porcelanite of siliceous clay intervals immediately below and above many storm beds dramatically enhanced the visibility of fair-weather ichnofabrics.

Thirty-two samples of submerged Nautilus macromphalus shells were recovered in 2008 from Lifou, Loyalty Islands in the South Pacific Ocean. Specimens were collected from carbonate-dominated sediment in water depths of 1–3 m. Some specimens were partly buried, whereas others rested on the seafloor. The majority of the specimens (66%) were recovered in a horizontal position, whereas 34% of the specimens were oriented vertically. Some specimens were pristine, with sharp color stripes and little encrustation by algae, cyanobacteria, or epizoans. The majority of specimens have substantial algal and cyanobacterial overcoats with some epizoans. In some specimens, the overcoats also trapped substantial amounts of carbonate sediment. Comparison of the 2008 collection of subtidal specimens to 43 beached Nautilus shells collected in 2002 from the same location reveals that the nearshore taphonomic pathways for drift cephalopod shells can be more complicated than published theoretical models suggest. Nautilus shells may or may not float directly to the beach. Shells not immediately deposited on the beach sink in the shallow water in a vertical position. Weight added by attached organisms and water infiltration, causes the submerged shells to eventually assume a horizontal position. Waves, currents, and bioturbation can then flip the shells over from side to side. Eventually submerged shells are buried, broken apart, or transported onto the beach. Beached shells that follow this taphonomic pathway have conspicuous algal coatings compared to those that simply float to shore. The Lifou subtidal population represents the first substantial modern externally shelled cephalopod collection from a shallow water environment to be analyzed to determine its taphonomic pathways. Conclusions from this analysis can be applied to nearshore deposits that contain externally shelled, fossilized cephalopods.

Integrated Ocean Drilling Program (IODP) Expedition 311 at the Cascadia Margin, northeastern Pacific, provides an excellent opportunity to study the response of carbon isotopic compositions of benthic foraminifers to episodic methane seep events in a gas hydrate geosystem. The shallow infauna benthic foraminifer species Uvigerina peregrina and Bulimina mexicana collected from five sites (U1325, U1326, U1327, U1328, and U1329) exhibit dramatic negative carbon isotopic excursions (−0.75‰ to −2.74‰, −1.11‰ to −2.62‰, −0.51‰ to −2.75‰, −0.58‰ to −2.71‰, and −0.22‰ to −3.32‰ respectively) and positive oxygen isotopic anomalies (3.27‰ to 4.91‰, 3.16‰ to 4.78‰, 3.37‰ to 4.88‰, 3.45‰ to 4.88‰, and 3.4‰ to 4.88‰ respectively). Results indicate that gas hydrate dissociation influenced the dissolved inorganic carbon of the pore water via anaerobic oxidation of methane. SEM analysis of foraminifer tests and the comparative carbon isotopic analysis of previous works on this subject indicate minimal alteration caused by diagenesis and authigenic carbonate precipitation. Carbon and oxygen isotopic values of these two species at Site U1327, U1328, and U1329 show episodic stratigraphic fluctuations, suggesting episodic gas hydrate dissociation and methane release possibly related to 100 ka sea-level fluctuations. δ¹³C of these two species at Site U1325 and U1326 at the stage of gas hydrate formation show one and two events of methane release respectively, indicating methane seeps occurred in the recent millennium probably because of the lowered sea level. The negative δ¹³C excursions and positive δ¹⁸O anomalies of benthic foraminifers could be indicators of episodic methane seep events associated with gas hydrate dissociation in marine gas hydrate geosystems.

The Eocene–Oligocene transition (ca. 33 Ma) is associated with one of the most pronounced climate changes of the Cenozoic, with continental mean annual temperature dropping ∼8 °C over a span of ∼400,000 years. Leptomeryx is a small, ruminant artiodactyl that spans the transition, known from the late Eocene (Chadronian North American Land Mammal Age, or NALMA) through the early Oligocene (Orellan NALMA). The hypothesis that early Oligocene Leptomeryx had more complex enamel surface area than those found in the late Eocene has been demonstrated qualitatively, but the potential change in the amount of enamel has never been quantified. Here we calculate the area of the occlusal surface enamel (OSE) of Leptomeryx specimens from both the Chadronian (n  =  29) and Orellan (n  =  35) of northwestern Nebraska. Areas of the OSE were calculated by isolating the enamel into polygons on digital photographs of each specimen. The mean areas confirm that the OSE significantly increased by approximately 27% from the Chadronian sample to the Orellan sample.