The lower Miocene Estancia 25 de Mayo Formation consists of shallow-marine to estuarine deposits that bear numerous oyster shell beds distributed throughout the succession. Facies analysis reveals that oysters grew in the nearshore paleoenvironments of both the lower Quién Sabe and the upper Bandurrias members. Two oyster species were identified: Crassostrea(?) hatcheri, distributed in the lower two thirds of the column, and Crassostrea orbignyi, distributed in the upper third of the column within the transition from marine to the fluvial deposits of the overlying Santa Cruz Formation. Petrographic, cathodoluminiscence, and carbon and oxygen stable isotope analyses of individual growth increments were performed on carbonate from all the oyster beds, together with consecutive time-series analyses for one specimen of each species. The isotopic composition of the shell seems to be associated with the microstructure of the growth increments. Selective diagenetic alteration affected chalky growth increments; whereas translucent (foliated and prismatic) growth increments are well preserved and can be used to infer paleoenvironmental conditions. Isotopic data indicate that C.(?) hatcheri lived in normal marine waters with a range of paleotemperatures from 10.6 to 20.5 °C. Monospecific beds of this oyster are related to opportunistic and quick colonization of the sea bottom. More negative δ¹³C and δ¹⁸O values in C. orbignyi shells likely reflect decreased paleosalinities, and the resultant environmental stress controlled the development of these low-diversity oyster accumulations. The separate stratigraphic distribution of each species was therefore determined by the paleoenvironmental conditions.

Predators of extant decapod crustaceans are fairly well known, but unlike many other invertebrate clades, not much is known regarding predation evidence found on fossil decapods. Herein, we provide an overview of such predation and expand upon this through an extensive study of fossil decapod specimens from multiple museum collections. Thus far most examples of predation come from drill holes and stomach contents; bite marks, incisions or irregular holes, and possible regurgitated material are also known. The currently recognized predators of decapods in the fossil record are fish, plesiosaurs, ammonites, octopods, and gastropods. We also provide new evidence of unambiguous drill-hole predation in decapods, based on 33,593 nonmoldic Cenozoic (middle Eocene–Holocene) decapod remains originating from Europe, Asia, and North America, indicating that drilling predation in decapods is more common than currently recognized. Drill holes attributed to octopods (ichnotaxon Oichnus ovalis) and gastropods (O. simplex and O. paraboloides) were found in carapaces and appendages from the Pliocene of the Netherlands, the Pleistocene and Pliocene of the United States (Florida), and the Pleistocene and early Miocene of Japan. Six drill holes attributed to octopods were found in epifaunal and semiburrowing crabs; three drill holes attributed to gastropods were discovered in semiburrowing and epifaunal crabs, and in a burrowing mud shrimp; and the producer of two other drill holes in epifaunal crabs is unknown. Other possible drill holes occur in decapods from the Holocene and early Miocene of Japan and the late Eocene of the United States. Drill-hole predation intensities in decapod faunas by stratigraphic formation are low (≤2.7%), at least in part due to multiple biases such as preservation and molting.

Sponges generally live firmly attached on firm- and hardgrounds but a few species are known to colonize mobile sediments in shallow water. These psammobiontic sponges are anchored to the bottom by incorporating sediment particles at their base. Herein we relate so-far enigmatic bowl-shaped structures from seagrass deposits of the lower Miocene (Burdigalian) Calcari a Briozoi e Litotamni Formation on the Latium-Abbruzzi carbonate platform (Central Apennines, Italy) to the in-ground parts of psammobiontic sponges. The sponge fossils yield a peculiar foraminiferal assemblage with an increased abundance of Bulimina and Bolivina compared to the surrounding sediments as well as with planktic foraminifers and spirillinids (Spirillina, Patellina), which are not recorded outside the sponges. Drifting planktic foraminifers became trapped on the sponge surface exposed to the water column before agglutination. In contrast, high quantities of Bulimina, Bolivina, and spirillinids indicate commensalistic relationships with the sponges. Generally, ecological interactions between foraminifers and living sponges are poorly documented. In the present case the infaunal Bulimina and Bolivina have been attracted by a low-oxygen and nutrient-rich environment, which developed in the progressively decaying buried part of the sponges along with early lithification, while the epifaunal spirillinids populated the internal network of water channels, which provided protection and food supply. The high abundance of generally rare Spirillina in Late Jurassic sponge reefs indicates a persistent ecological preference of spirillinids to sponge microhabitats.

Several meltwater floods initiated by the Laurentide Ice Sheet (LIS) drained to the Gulf of Mexico (GOM) through the Mississippi River during the last deglaciation (10–21 cal ka [calibrated kiloannum]). Such floods have been efficiently captured in the geochemical record of the Jumbo Piston Core 26 (JPC-26) from the northwestern GOM as distinct peaks in the content distribution of Si, Al, and Fe due to their common occurrence throughout North America. On the other hand, peaks in the content distribution of Ti, K, Zr, and V adequately describe the sediment source of each flooding event due to their clustered areal distribution in North America. The presence of three distinct peaks in the distribution of Si, Al, and Fe at 8.5, 5.2–7.6, and 2.9–3.5 cal ka indicates that events of enhanced Mississippi River discharge (EMRD) occurred during the Holocene as well. The geochemical signature of these flooding events suggests that their origin and sediment source is variable, depending on the retreating state of the LIS and the prevailing precipitation patterns in North America during these time periods. A comparison of the 8.5 and 2.9–3.5 cal ka EMRD events with the oxygen isotope and gas (CH₄) records of the Greenland Ice Sheet Project 2 (GISP-2) ice core denotes that these events might be linked to short global warming episodes associated with periods of increased solar irradiance. The 5.2–7.6 cal ka EMRD event is associated with the Holocene Thermal Maximum, which resulted in the intensification of the North American monsoonal circulation.

This study examines the distribution of larger foraminifera in an upper Campanian–lower Maastrichtian siliciclastic–carbonate depositional environment within the Arén Sandstone Formation. Three assemblages have been identified, which refer to prodelta, reef, and lagoon depositional facies. Prodelta deposits are characterized by Lepidorbitoides socialis, Lepidorbitoides aff. minor, Clypeorbis mammillata, and Siderolites cataluniensis. The reef deposit assemblage contains Siderolites calcitrapoides, Siderolites cataluniensis, Orbitoides gruenbachensis, “Orbitoides” aff. concavatus, Lepidorbitoides aff. minor, and Fallotia jacquoti. They are associated with the encrusting foraminifera Solenomeris and Haddonia. The lagoonal assemblage contains Fascispira colomi and Omphalocyclus macroporus. Among the siderolitids, the keeled saucer-shaped Siderolites cataluniensis colonized the deepest environments at the lower photic zone, whereas the canaliculate spine-bearing Siderolites calcitrapoides characterized shallower waters. The former lived on soft media of calm environments whereas the latter crawled on firmground of high-energy environments. Lepidorbitoides socialis shared with Siderolites cataluniensis and Clypeorbis mammillata the deepest, calm environments, while Lepidoritoides aff. minor adapted to a wide range of depths in low to moderate water-energy environments. Orbitoides gruenbachensis and “Orbitoides” aff. concavatus colonized the firm media in the upper photic zone, whereas Omphalocyclus macroporus was an epiphyte in soft media in areas with a moderate-energy water. The meandropsinids occupied the upper photic zone; the odd pair Fallotia jacquoti and Eofallotia simplex colonized high-energy environments, whereas their relative Fascispira colomi adapted to shallow, calm environments. The structure of the assemblages of larger foraminifera described in this paper provides a useful tool for the reconstruction of the Late Cretaceous shallow-water fauna in mixed siliciclastic-carbonate environments.

Assessments of global Pliocene climate using conventional proxies indicate prevalent warmth at mid- to high latitudes. How this climate change was manifested on a regional basis and on annual timescales remains poorly understood. Oxygen isotope ratios (δ¹⁸O) of fossil Mercenaria spp. (bivalve) shells enable reconstruction of growth temperature to estimate sea surface temperature (SST) at seasonal resolution. Comparing growth characteristics of fossil and modern populations potentially provides independent SST constraints. Fossil shells were selected from the Rushmere Member of the Yorktown Formation (Pliocene, early Piacenzian, ∼3.3–3.0 Ma, warm interval) and the Chowan River Formation (Pleistocene, Gelasian, 2.4–1.8 Ma, subsequent cooling) of the U.S. Mid-Atlantic Coastal Plain (MACP). The coldest winter temperatures recorded in the Yorktown Formation shells averaged 17 ± 2 °C and the warmest summer temperatures averaged 25 ± 2 °C. Chowan River Formation shells recorded the coldest winter temperatures averaging 12 ± 2 °C and the warmest summer temperatures averaging 21 ± 2 °C. Modern winter and summer SST is 6 ± 2 °C and 24 ± 2 °C, respectively. The vast majority of data do not approach temperature growth limits of Mercenaria; thus, shells of the Yorktown and Chowan River formations document reduced seasonality relative to modern conditions. Population growth analyses do not provide reasonable quantitative SST estimates. They provide further evidence, however, that fossil populations likely grew in warm-temperate conditions. Isotopic results are consistent with notions of increased meridional heat transport during the Pliocene.