A high-resolution paleoecological analysis of an outcrop of the Pleistocene Fort Thompson Formation was conducted at the Caloosa Shell Quarry near Ruskin, Florida. This study was designed to create a conceptual framework for future evolutionary and paleoecological studies. A massive shell bed was sampled using bulk replicate sampling of small stratigraphic intervals in several stratigraphic sections. The data set derived from the molluscan remains was analyzed using principal components, factor, and cluster analyses to define fossil assemblages. Guild analyses and comparison to modern analogs of the ancient species were used to determine the most likely set of paleoenvironmental and paleoecological conditions at the time of deposition.

Multivariate analyses indicate two distinct faunal assemblages. An assemblage dominated by the bivalve Carditamera floridana and other grass-dwelling mollusks was recognized from the lower zone of the outcrop. Samples from the upper zone contained an assemblage dominated by the burrowing clam Chione cancellata as well as other grass and sand dwelling mollusks. The lower zone assemblage had lower paleoecological complexity, and a higher abundance of the opportunistic, salinity-tolerant mactrid Mulinia lateralis, indicating less stable paleoenvironmental conditions.

These results indicate that there were two distinct sets of conditions in effect at different times during deposition. The earlier fauna indicates the presence of sea grass, but also environmental instability, perhaps due to fluctuating salinity. Later, a richer fauna combining sea grass-dwelling organisms with sand-loving taxa developed.

Morphometric and further paleoecologic analyses of individual taxa common to both faunal assemblages uncovered significant variability correlated with paleoenvironmental setting. Without the conceptual framework deduced from the paleoecologic analysis, this variability would have been either missed or difficult to interpret.

Large (up to 9.5 cm wide) and robust Cruziana ichnofossils are present in the Middle Triassic (Ladinian) Toad and Liard formations in northern British Columbia, Canada. These trace fossils are the first definitive occurrences of large Cruziana from post-Paleozoic marine strata. These traces, assigned to a new ichnospecies (Cruziana seilacheri), are similar in many respects to traces from the Lower Paleozoic, including the Cambrian ichnotaxon Cruziana rusoformis and the Ordovician ichnotaxon Cruziana furcifera. The morphology and orientation of scratchmarks in these traces suggest that they may have been constructed by either stomatopod or decapod crustaceans. The similarity of the Toad-Liard Cruziana to lower Paleozoic forms and their presence in post-Paleozoic marine rocks demonstrate that care should be taken when utilizing these traces as indicators of either Paleozoic deposition or a specific tracemaker.

Detailed study of Oxfordian coral-microbialite reefs in the Swiss Jura Mountains has identified major paleoecological variations in space and time, which are attributed to environmental changes. Micro- and macroscale semi-quantitative analyses of microbialite types, micro-encrusters, bioerosion, corals, and other macrofauna composing the reefal facies were performed. Three main trophic structures (dominant nutritional modes) were recognized: phototrophic-dominated, balanced photo-heterotrophic, and heterotrophic-dominated. A phototrophic (light-dependant) fauna dominated reefs growing in pure carbonate and nutrient- poor environments, where sedimentation rate was the main factor controlling reef growth. In mixed siliciclastic-carbonate platform environments, a balanced photo-heterotrophic fauna with periodical shifts to heterotrophic-dominated associations was induced by freshwater and sediment run-off into closed, shallow lagoons. In this case, the main factors controlling reef growth were the distribution and accumulation of terrigenous sediment on the platform and/or associated nutrient availability. The balanced photo-heterotrophic structure found in mixed carbonate-siliciclastic settings produced the most diversified reefs, suggesting that these Oxfordian reefs preferentially thrived in water moderately charged with nutrients (mesotrophic environment). In the case of strong siliciclastic accumulation and/or strong increase in nutrient availability, coral reef diversity dropped drastically and heterotrophs dominated the trophic structure. A model of the evolution of trophic structure in these reefs as a function of the governing environmental factors is proposed. Focusing on the dominant nutritional mode at each step in reef evolution allows a detailed characterization of reefal structure and a better understanding of the processes leading to coral reef settlement, development, and demise.

Depositional cycles in fluvial successions are described here as chronostratigraphic packages of strata founded on a laterally extensive, scour-based, amalgamated channel-sand body, overlain by mudrocks, isolated channel fills, avulsion and splay complexes, and paleosols. Ten packages are described from the lower Horseshoe Canyon Formation (Campanian-Maastrichtian), one of a succession of clastic wedges filling the Alberta foreland basin in south-central Alberta. The structure of these packages is consistent with the fall-rise-fall cycle of base-level described in other studies, but the package-bounding scours and internal surfaces are discontinuous and difficult to trace in the mudrock-dominated strata. Terrestrial vertebrate fossils are preserved in relatively fossiliferous, facies-independent horizons 1 to 3 m thick that statistically correlate with the stratigraphic position of package scours and surfaces. Fossiliferous horizons formed as a result of attritional accumulation under an optimum, relatively low, regional deposition rate. Not only do these horizons aid in locating package surfaces, but they also provide insight to the interaction of the package-scale, base-level oscillation with the larger-scale fluctuation in accommodation associated with the formation of the clastic wedge. As such, fossiliferous horizons in the Horseshoe Canyon Formation make better boundary markers than do paleosols, splays, coal seams, or even the surfaces associated with package structure. Therefore, the vertebrate fossil record may supply a means of stratigraphically evaluating sections in other locations in which typical sedimentological and architectural cues for surfaces are absent.

Nothing is known about the community-scale plant ecology of early Cretaceous volcanic environments in the southern high latitudes. The paleoecology of the early Aptian (119–120 Ma) volcaniclastic Cerro Negro Formation of South Shetland Islands, Antarctica, has been investigated to improve understanding of these enigmatic ecosystems. This unit was deposited in an intra-arc setting at the edge of the paleo-polar circle (66°S). Taphonomic analysis of megaflora in seven volcanic facies indicates the existence of a spatially complex vegetation mosaic co-dominated by conifers, bennettites, and ferns. A lower stratigraphic unit was deposited by high-magnitude, low-frequency silicic eruptions, partially reworked by fluvial processes. Following ash falls, shrubby communities of ferns and bennettites dominated for short periods in low-altitude paleovalleys before being replaced by araucarian-podocarp-fern conifer forests. Forests of podocarp conifers and bennettites covered adjacent mid-altitude slopes of active volcanic cones. These were destroyed periodically by hot pyroclastic flows, and their charred remains washed down into paleovalley fluvial systems. Analysis of architectural and phenological data from both major forest communities indicates the predominance of evergreen trees with a canopy height of c. 20–30 m. Growth-ring analysis indicates that, despite occasional catastrophic eruptions, growing conditions were mostly favorable and uniform, although in riparian paleovalley niches flooding locally produced more stressful growing conditions. An upper stratigraphic unit was deposited by low-magnitude, high-frequency basaltic eruptions. Shrubby, fern and bennettite-dominated vegetation, together with local conifer stands, colonized this environment. Growth of more widespread arborescent vegetation in the upper unit was inhibited by high-frequency volcanic disturbances. Bennettites are much more abundant and diverse in the Cerro Negro Formation compared with coeval, non-volcanic sites in the southern high latitudes, indicating that this group may have favored volcanic environments.

Nereites ichnofabrics (comprising N. missouriensis) occupy the upper 3–7 cm in brown, oxidized, soft to soupy, uniformly fine-grained sediments that accumulated at a low rate (<5–6 cm/kyr) at water depths >4000 m water in the central South China Sea. Nereites are nearly vertical close to the sediment surface, become increasingly more inclined with depth, and, just above the redox boundary, they show a winding, subhorizontal course. The Nereites producers appear to be guided chemotactically as they maintain a consistent distance relative to the redox boundary, despite variation in depth of penetration between studied sites. The transition from oxic to anoxic conditions is characterized by high concentrations of microbial biomass on which the Nereites producers are inferred to feed. Thus, the Nereites tier in fossil ichnofabrics may reflect the position of the redox boundary. Ash-filled burrows below the 1991 Pinatubo ash layer imply surface-feeding activities of the Nereites-producing animals. However, the small amount of ash in the burrows demonstrates only subordinate use of surface sediments, probably during periods of enhanced particle flux following upwelling. Based on the number of ash-filled burrows and the number of upwelling periods, an average population density of the Nereites producers of 5–6 animals per m² is estimated.

The first Late Cretaceous dinosaur tracksite recorded from Arizona, preserving over 100 footprints, also preserves sinuous grooves here interpreted to be impressions left by the tail of a large vertebrate as it dragged through sediment now assigned to the Toreva Formation. Although no footprints are preserved that can be referred unambiguously to the individual or individuals that produced the tail-drag marks, the dynamic nature of the surface upon which the tracks were made, likely a river or stream shoreline, could have easily resulted in their disturbance or obliteration. As best as can be determined on the basis of a depauperate marine fauna from the lower part of the unit, and on the basis of a substantial hiatus that separates the lower and upper parts, the site is probably middle Coniacian in age. These tracks and drag marks add significantly to the exceptionally rare record of terrestrial vertebrates known from the Toreva Formation.

Marine hard-substrate communities are important ecological and evolutionary resources for paleontologists and neontologists, yet their study is handicapped by numerous terms that are used inconsistently. A rationalized nomenclature system is proposed for plants and animals that encrust or bore natural marine hard substrates. The terms describe the identity of the colonizing organism, the nature of the substrate, and the location of the colonist (on the surface or within the substrate). These terms follow simple principles, making them easy to construct and interpret. A new collective term also is introduced: a sclerobiont is any organism (animal or plant) fouling any kind of hard substrate.