Three categories of fossil aggregates are recognized in the Lower Cambrian Maotianshan Shale biota from SW China: (1) elliptical aggregates with randomly distributed exoskeletal remains of typically small- to medium-size bivalved arthropods (e.g., ostracode-like bradoriids, phyllocarid-like waptiids), hyoliths, and trilobites are interpreted as coprolites, possibly produced by anomalocaridids (e.g., waptiid-rich coprolites) and/or unknown epibenthic predators; (2) elongate, ribbon-like aggregates composed of oriented small hyolith shells, interpreted as the feces of infaunal carnivorous worms such as priapulids; and (3) concentric aggregates, typically with a central nucleus (e.g., remains of medusoid eldoniids or bivalved arthropod carapaces) and peripheral exoskeletal fragments, possibly generated by bottom currents whirling around carcasses. These new coprolite data add to morphofunctional information obtained from fossil organisms and indicate that predation occurred at different levels of the water column with: (1) endobenthic predators (diverse priapulid fauna) feeding near the sediment-water interface; (2) epibenthic predators/scavengers (almost exclusively arthropods); (3) predators living in the lower levels of the water column (e.g., anomalocaridids); and (4) mid-water predators exploiting upper levels in the water column (e.g., eldoniids, ctenophores, chaetognaths). Communities living at or close to the water-sediment interface (epibenthic sensu stricto, meiobenthic, and demersal animals) were exposed to a multidirectional predatorial pressure from infaunal, epifaunal, and mid-water predators. Although predation was diverse, nothing indicates that the food chain extended beyond the level of primary carnivores. Animals already had acquired complex behaviors such as hunting (e.g., anomalocaridids, priapulids) and predator avoidance in which sensory systems were involved. The example of the Maotianshan Shale indicates that the burst of anatomical innovations (new body plans) that characterizes the early Cambrian also was accompanied by the rapid development of new feeding strategies and by an unprecedented expansion of ecological interactions (prey-predator relationships).

Enigmatic microfossils from the early Silurian of Poland known as mazuelloids (= muellerisphaerids) have been identified as Baltisphaeridium-like acanthomorphic acritarchs that have been subject to post-mortem phosphatization. These acritarchs were the dominant components of large post-bloom macroaggregates that probably sank rapidly to the seafloor and were then overgrown by benthic coccoid cyanobacterial mats. Early diagenetic phosphatization of the remains probably occurred following shallow burial and in proximity to decomposing phosphate-rich macroaggregates. Depending on phosphate availability, the resulting phosphate layers were thin or thick and were deposited on the outside, inside, or enveloping the acritarch organic walls from both sides. The unusually large size of the mazuelloid-forming acritarchs was probably the result of periodically hypertrophic conditions driven by large blooms generated by upwelling currents.

Patchiness affects fine-scale patterns of biological variation because compositional differences among localities depend on the composition of the patch sampled for paleoecological analysis. This can inflate compositional differences among localities that otherwise may have similar faunal constituents, which can obscure the true signal of biotic composition. In the type Cincinnatian Series, comparisons of fine-scale faunal-assemblage patterns acquired through gradient analysis have been difficult to accomplish because of significant deviations in biotic composition. Here, the role of patchiness in creating these deviations is tested by quantifying the amount of lateral variation in composition at a single outcrop of the Kope Formation. Because the lateral expression of individual beds in the Cincinnatian is variable, patchiness is more effectively assessed for bedsets rather than individual beds.

Using gradient analysis to evaluate lateral variation at one locality reveals that patchiness is the cause of fine-scale stratigraphic deviations, which are typically produced by the addition or subtraction of just a few taxa. Furthermore, this lateral variability is less for limestone bedsets than for many mudstone bedsets. This supports the idea that limestone beds in the Cincinnatian contain assemblages that are more time-averaged than many, though not all, mudstone beds. Because fine-scale faunal patterns are dependent on the composition of the sampled patch, replicate sampling is necessary to account for patchiness. Despite the effects of patchiness and time-averaging at scales of one or a few beds, biotic composition patterns acquired through gradient analysis are robust among localities at scales greater than a few beds.

Coprolites were collected 74 m above the base of the Upper Triassic Ischigualasto Formation of northwestern Argentina and their chemistry, mineralogy, and textures were studied to infer their biological source and taphonomy. They were found to contain a few fragments of bone and much crystalline apatite, and so can be assigned to carnivores able to digest bone. Primary minerals derived from endogenous materials were apatite and pyrite, and secondary minerals derived from ground water were chiefly calcite and glauconite in one coprolite and glauconite in another. Primary apatite, presumed originally to have been mostly dahllite (a carbonate hydroxyapatite) precipitated from digested bone, was converted to francolite (a carbonate fluorapatite) during diagenesis through the introduction of fluoride from ground water. The chemistry, mineralogy, and structure of the coprolites suggest an early onset of mineralization, early anaerobic burial, and a recent anaerobic-to-aerobic transition during weathering. The chemistry of the coprolites is consistent with the stratigraphic identification of the coprolite horizon as an ancient flood plain.

The Early Albian Oceanic Anoxic Event 1b (OAE 1b) black shale is interrupted by one or more ventilation events that display significant changes in benthic and planktic populations. Within the OAE 1b sections studied, at ODP Site 1049, DSDP Site 545, and the Vocontian Basin, the benthic foraminiferal repopulation events last between ∼500 and ∼1,250 years and occur with a cyclicity of approximately 5.7 kyr. This period may represent an amplitude modulation of the precessional cycle. The OAE 1b sections from the marginal setting of the Vocontian Basin exhibit up to eight repopulation events. In contrast, there is only one repopulation event identified in the Atlantic OAE 1b sections from the Mazagan Plateau (DSDP 545) and Blake Nose (ODP 1049). Within the margin of dating uncertainties, this supraregional repopulation event occurred synchronously in the Vocontian Basin and the Atlantic Ocean. While the OAE 1b black shale formed under extremely warm and humid conditions, the repopulation events occurred during intervals of short-term cooling and reduced humidity at deep-water formation sites. The resulting increase in evaporation led to enhanced formation of low-latitude deep water, thus improving the ventilation of the sea floor.

Shells of the extremely long-lived bivalve mollusk Arctica islandica (Linnaeus 1767) provide century-long, multi-proxy records of inter-annual environmental variability in middle- to high-latitude marine settings. Reliable interpretation of these climate archives, however, requires exact knowledge of the length and timing of the growing season and which environmental parameters control shell growth rate during the year. Here, intra-annual growth microstructures, δ¹⁸O-derived ambient water temperatures, and δ¹³C from A. islandica shells collected from the southern and central North Sea are studied. Such data were analyzed in conjunction with observational sea-surface temperature and primary productivity data. Arctica islandica produces circadian growth increments in its shell (on average 31.5 μm per day during age four, measured along the outer shell surface), which allow assignment of calendar dates to each shell portion. The growing season of A. islandica in the upper mixed layer of the ocean (here 25 m water depth) is not continuous over an eight-month period as previously suggested. Rather, it is interrupted during spawning between early September and mid-November. In addition, shell production ceases or is strongly retarded due to food scarcity between mid-December and mid-February. Water temperatures derived from oxygen-isotope ratios are in good accord with observed sea-surface temperatures. In specimens at 25 m water depth, abrupt changes in shell δ¹⁸O-derived temperature (T_δ18O) were interpreted to represent vertical displacements of the seasonal thermocline. Daily shell growth is controlled by temperature and food availability. Up to 58% of the variation in daily growth rate is explained by these environmental parameters. This study demonstrates that A. islandica can provide seasonal to subseasonal, precisely dated proxies of environmental variables. Such data are of increasing importance for climate models.