We document massive deposition of carbonate sands along the south shore of Bermuda that were emplaced during one or two great storms during the last interglacial. As determined by their stratigraphic position and geochronological data, these deposits formed during marine isotope substage (MIS) 5c ca. 100 ka ago. Within a leeward set of eolian beds, evidence of a living landscape was preserved that includes delicate footprints of a shorebird (Scolopacidae, Catoptrophorus) preserved in frothy dune foreset beds. In the same stratigraphic unit, outlines of a standing forest of palm trees (Sabal bermudana), some evidently with fronds in place, were molded in the fine carbonate dune sand. All available evidence points to an MIS 5c sea level positioned several meters below the present datum, which would require great intensity of storms to transport such voluminous deposits well above present sea level. Waves and storm currents transported loose sediments from the shallow shelf onto the shore, where hurricane winds piled up sand sufficiently deep to bury established forests of 8- to 10-m-tall trees. Evidence of such powerful storms preserved in the rock record is a measure of the intensity of past hurricanes, and a possible bellwether of future storm events. Entombment of the trees involved rapid burial and cementation creating external molds in limestone, a process that is important in the development of vertical hydrological conduits commonly observed in eolianites.

Studies that assess the ecological fidelity—preservation of the original community—of terrestrial shell accumulations are uncommon but essential to infer accurate changes in past ecosystems. When live-dead comparisons are unavailable, the taxonomic agreement between differing taphofacies may be used to evaluate the fidelity of ancient shelly assemblages. This approach was used to approximate the fidelity of Quaternary land snails preserved in carbonate-rich paleosols from the northeastern islets of the Canary Archipelago. Such macroscopic alteration as fragmentation, corrosion, carbonate coating, and color loss affected shells, however, microscopic analyses concluded substantial diagenetic alterations unlikely. The shell abundance negatively correlated with fragmentation, suggesting that a higher proportion of shells may be a consequence of higher shell input rate and lower shell destruction rate rather than lower sedimentation rate, as predicted by taphonomic models. Strongly and weakly altered taphofacies significantly differed in species abundances. Substantial taphonomic bias was improbable, however, because both taphofacies contained taxa with comparable durability. Temporal fluctuations in taphonomy and ecology suggest variable environmental conditions operated through time. The overall decline in shell abundance from the last glacial to interglacial paleosols may be explained by a decline in humidity and reduced island surface area resulting in lowered snail proliferation, and in turn, a decreased net shell input rate. This study emphasizes that the original community is preserved within the studied terrestrial shell accumulations regardless of the degree of taphonomic alteration. Measures of past taxonomic richness and diversity, therefore, may be used as a reliable measure of the original snail community.

Distribution, growth rate, and carbonate production of non-geniculate and unattached coralline red algal beds (rhodoliths) were studied in the Gulfs of Panama and Chiriquí along the Pacific coast of Panama. This is the first attempt to quantify coralline carbonate production in this region based on a newly developed algorithm. Although situated at the same latitude, the two gulfs are characterized by distinctly different environmental conditions; Chiriquí is mesotrophic throughout the year, whereas the Gulf of Panama is eutrophic due to intense seasonal upwelling. Coralline algal carbonate production is ∼10× greater in the Gulf of Chiriquí (11.258 × 10¹⁰ gr CaCO₃ yr⁻¹) than in the Gulf of Panama (1.69 × 10¹⁰ gr CaCO₃ yr⁻¹), which is characterized mostly by siliciclastics with minor carbonates. Corallines display a patchy distribution in both gulfs being concentrated mainly around the islands. In Chiriquí, they occur as thin crusts as well as massive-nodular and open-branching growth types; encrusting types are most common in the Gulf of Panama. Growth rates of branching corallines were calculated based on annual growth bands matched to their skeletal Mg/Ca ratios. Ratios are higher in the less dense portions of growth bands corresponding to higher growth rates during the dry season, whereas both Mg/Ca ratios and growth rates in the dense portions (wet season) drop. Growth rates of branch tips in both sites are similar to those reported from other temperate-subtropical regions. Extremely slow growth rates combined with the old ages of individual thalli document the overall stability of this algal ecosystem.

This study is the first assessment of mollusk fossil assemblages relative to the compositional fidelity of modern mollusk living and death assemblages. It also shows that the sedimentary record can provide information on the original, non-human-impacted, freshwater malacofauna biodiversity, based on Late Pleistocene shells. The fossil mollusk assemblage from the Touro Passo Formation (Pleistocene–Holocene) was compared to living and death assemblages of the Touro Passo River, southern Brazil, revealing little resemblance between fossil and live-dead species composition. Although the living and death assemblages agree closely in richness, species composition, and species relative abundances (both proportional and rank), the fossil assemblage differs significantly from both modern assemblages in most of these measures. The fossil assemblage is dominated by the native endemic corbiculid bivalve Cyanocyclas limosa and the gastropod Heleobia aff. bertoniana. These are absent in the living assemblages, and both living and death assemblages are dominated by the alien Asiatic corbiculid C. fluminea, which is absent in the fossil assemblage. The fossil assemblage also contains, overall, a higher proportional abundance of relatively thick-shelled species, suggesting a genuine bias against the thinner- and smaller-shelled species. Our results suggest that contemporary environmental changes, such as the introduction of some alien freshwater mollusk species, together with post-burial taphonomic processes, are the main factors leading to the poor fidelity of the fossil assemblage studied. Hence, the taxonomic composition of the Late Pleistocene mollusks from the Touro Passo Formation probably would show greater similarity to present-day assemblages wherever the mollusk biodiversity is not disturbed by human activities.

Ecological and taxonomic study of the mollusk-rich fauna of the Golfe d'Arguin, North Mauritania, investigates the various environmental influences affecting this tropical shelf. The upwelling of nutrient-rich waters leads to a highly productive environment under tropical conditions. The resulting mixed carbonate-siliciclastic sediment contains a large portion of calcareous components produced by heterotrophic organisms—e.g., mollusks, foraminifers, worms, barnacles—that are reworked on the open shelf. On the basis of mollusk assemblages, six taphocoenoses are defined, all being characterized by a mixed fauna of tropical (e.g., Tellina densestriata), subtropical (e.g., Macoma cumana) and temperate (e.g., Spisula subtruncata) species. Differences between the assemblages are related to the medium—grain size ranging from mud to gravel—that results from local hydrodynamic conditions and water depth. Among carbonate grains, Donax burnupi shells are very abundant in the swell-exposed, northern part of the Golfe d'Arguin and reflect the tropical to subtropical, high-energy, and high-nutrient waters. Mollusk assemblages are demonstrated to be a sensitive tool for deciphering complex environmental conditions in sedimentary archives.