Cluster analysis reveals eight biofacies during a time of faunal turnover and regional oceanographic change in the middle Upper Ordovician of central Kentucky. These biofacies are arranged along a deep-water to shallow-water gradient, with the dalmanellid and the Sowerbyella biofacies in offshore facies, the Rafinesquina, the atrypid, and the ramose trepostome biofacies in deep-subtidal to shallow-subtidal facies, the Constellaria-Cyclonema and the Rhynchotrema biofacies in the shallow-subtidal facies, and the Solenopora-Hebertella biofacies in sand-shoal facies. These biofacies are not discrete, but rather they share a large number of taxa suggesting that they are arbitrary subdivisions of a depth-related ecological gradient. Nonetheless, they are useful as a point of comparison with other studies of this time interval in the eastern United States. Previous lower and middle Upper Ordovician biofacies studies portray a similar pattern of plectorthines and rhynchonellaceans in the shallow subtidal, strophomenids in the deep subtidal, and dalmanellids and plectambonitaceans in the offshore, indicating an overall temporal consistency to many of these biofacies at suprageneric taxonomic levels. Similarly, values of preferred depth, depth tolerance, and peak abundance of most taxa are generally conserved, and this is particularly true for abundant taxa. Nonetheless, this 2-m.y. record also indicates temporal changes in the occurrence of some biofacies, in the relative abundances of taxa in some biofacies, in the species membership within biofacies, and in values of preferred depth, depth tolerance, and peak abundance for several taxa. Collectively these indicate a dynamic aspect to an ecosystem that otherwise displays several attributes of stability and underscore that ecologic stability should not be viewed as a simple dichotomy between stability and instability. The dynamic aspects of this ecosystem suggest that these biofacies were not governed by extreme degrees of species interactions that resulted in near constancy of biofacies structure. Continuous changes in water temperature, nutrient supply, and turbidity during this time may have been a contributing factor to changes within this ecosystem.

A uniquely preserved occurrence of the plectambonitoid brachiopod Sowerbyella rugosa from the Upper Ordovician of Northern Kentucky shows several individuals preserved in direct association with burrow-like structures and oriented with the commissural plane vertical and the hinge line down in the upper laminated siltstone of a tempestite bed. Two types of structures are present: (1) structures that document translational motion of convex-up brachiopods to the surface, then rotation to a vertical position with the commissure near the sediment-water interface; and (2) structures that show slightly longer-term occupation and sediment clearing around the brachiopods before they expired in the post-storm accumulation of fine mud. The abilities demonstrated by these individuals require a rethinking of the helpless-strophomenid paradigm. The peculiar plectambonitoid traits, mantle threads (as evidenced by interarea canals) and external mantle flaps (as evidenced by comae) were unlikely to have contributed to the ability of these individuals to burrow upward. Valve clapping is the only apparent means by which Sowerbyella rugosa could have moved through the sediment. If plectambonitoids could have moved by clapping their valves, then the same may have been true of strophomenoids, such as Rafinesquina alternata. The ability to move sediment and adjust position explains how strophomenids could live in a convex-up position or even, if partially buried, in more vertical positions, as documented by previous epibiont studies. These abilities suggest that geniculation may have served to anchor shells of active individuals in an inclined or vertical position in higher-energy environments of shifting substrates rather than to lift commissures of passive individuals in a convex-down position in lower-energy environments of rapid mud accumulation.

Upper Triassic assemblages containing the terebratulid brachiopod Rhaetina gregaria from a shallow, intraplatform carbonate setting of the Fatra Formation are classified according to biofabric, geometry, and internal structure into 6 deposit types, which are interpreted as: (1) autochthonous primary biogenic, (2) autochthonous winnowed or sediment starved, (3) parautochthonous storm-wave, (4) parautochthonous storm wave/flow, (5) amalgamated storm-reworked, and (6) allochthonous (long-term current/wave) deposits. Their distribution on the bed scale correlates with depth-related environmental gradients in regard to the position of fair-weather wave base, average storm wave base, and maximum storm wave base. The biofabric, geometry, and internal structure of brachiopod deposits were predominantly influenced by: (1) storm activity, related to variations in sedimentation rates and water energy; and (2) original variations in composition and spatial distribution of life associations. Fossil assemblages preserved in brachiopod deposits have a wide range of temporal resolution, ranging from census to environmentally condensed types. Brachiopod assemblages in the storm-reworked deposits probably were affected by catastrophic mortality. The distinction of brachiopod deposit types based on deposit-level criteria does not wholly correspond to the classification of taphofacies types based on intensity of shell alteration. The biofabric and associated deposit-level properties reflect final depositional processes (i.e., the rate and permanence of burial), whereas shell alteration of brachiopods reflects mainly variation in the nature of pre-burial environmental conditions. The lowest degree of alteration (i.e., low levels of bioerosion, micritization, encrustation, and disarticulation) is associated with deposits that were affected by storm-induced sudden burial. In general, settings with high proportions of micritic mud (associated with mixed brachiopod-bivalve associations) are characterized by relatively low alteration of brachiopods. These settings are in sharp contrast to hard-bottom settings (associated with coral associations), in which bioerosion and micritization are high. This difference in shell alteration is the effect of extrinsic factors related to lower turbidity, higher proportion of hardparts and higher storm reworking in latter settings.

Autochthonous/parautochthonous benthic associations dominated by the short-looped terebratulid Rhaetina gregaria are typical of settings below the fair-weather wave base, with background low-energy condition. This is in contrast to high-energy/hard-bottom occurrences of this association from other regions. The difference in preservation potential of brachiopods due to differential extrinsic factors (e.g., between hard- and soft-bottom settings) can substantially bias the understanding their ecology and temporal shifts in environmental preferences. Data about substantial bioerosion/micritization of brachiopods in some deposit types indicate their higher durability and inherently higher preservation potential in contrast to actualistic data about the poor resistance of modern brachiopods to destruction.

The end-Permian mass extinction was the largest Phanerozoic biotic crisis that resulted in significant and permanent ecological change. In order to examine ecological aspects of the recovery, shell beds deposited in environments ranging from nearshore to storm wave base were examined from three stratigraphic intervals in the Lower Triassic of the western U.S. Shell beds of the first interval, the Griesbachian Dinwoody Formation, are low-diversity, monospecific beds of Claraia and Promyalina, commonly with the inarticulate brachiopod Lingula. Data from the Nammalian Sinbad Limestone (Moenkopi Formation) provide a small window into the second time interval, in which common low-diversity (bivalves and microgastropods) shell beds occur. Within the third interval, represented by the Spathian Virgin Limestone (Moenkopi Formation) and Thaynes Formation, the bivalves Promyalina and Permophorus are found in both monospecific and polytaxic beds. Crinoids are also commonly found as encrinites and as significant contributors to the matrix of these beds. Shell beds range in thickness from pavements to 10s of centimeters and show variable internal complexity. The persistence of monospecific shell beds throughout these three intervals is significant as support for long-term stress during the recovery interval that is not apparent from sedimentological data alone. Although these Early Triassic beds primarily are comprised of members of the Modern Evolutionary Fauna, they are more similar to beds from the Paleozoic in thickness and taphonomic characteristics.

The encrustation of Paleozoic rhynchonelliform brachiopods has been studied for decades, but modern brachiopods have not received similar scrutiny. The discovery of abundant subtropical brachiopods from the Southeast Brazilian Bight provides an unprecedented opportunity to assess epibiont abundance, diversity, and encrustation patterns in modern brachiopod assemblages. Across the outer shelf, encrustation frequencies vary among taxa, from mean values of 0.45% for Platidia to 9.3% for Argyrotheca. Encrustation frequencies for Bouchardia increase from 1.6% on the outer shelf to 84% on the inner shelf. Larger valves are encrusted more frequently, and epibionts preferentially colonize valve interiors. Increased encrustation on the inner shelf may reflect the greater surface area of larger hosts, longer exposure of dead shells, water-mass characteristics, sedimentation rates, productivity, or other factors that vary with depth. Inner-shelf brachiopods exhibit encrustation frequencies comparable to those reported for epifaunal bivalves. The epibiont fauna is dominated by bryozoans and serpulids, with minor roles played by spirorbids, bivalves, barnacles, foraminifera, algae, and other taxa. Epibiont abundance at each site is highly variable, but sites are similar in rank importance of epibiont taxa. A different suite of epibionts colonized Paleozoic brachiopods, but similar patterns of encrustation have been observed, including preferential settlement according to valve morphology. These results provide a baseline for evaluating the encrustation of modern bivalves and ancient brachiopods, and may elucidate the macroevolutionary history of epibionts and their relationship to their hosts.

Time-averaging can be a major obstacle in reconstructing fine-scale ecological processes in the fossil record. This study presents a technique, Neighbor Proximity Analysis that attempts, despite time-averaging, to elucidate fine-scale ecological information on a single bedding plane. The technique takes advantage of the tendency for most sessile organisms to cluster in conspecific clumps, and assumes that time-averaging will tend to overprint patterns of conspecific clustering given sufficient time. The fossil species of interest is mapped onto an appropriate grid, point-counted, and the number of conspecific neighbors for each individual is counted. The community distribution is then permuted randomly for multiple iterations; and for each iteration, the number of randomly generated conspecific neighbors is compared to the observed number of conspecific neighbors. Taxa that exhibit clustering greater than expected under the random model probably clustered in life, revealing features of the local spatial structure. An example of the method is presented, using bedding planes from the Rapid Member of the Little Cedar Formation at the Devonian Fossil Gorge, Coralville, Iowa. The results indicate that of the common brachiopod present, Spinatrypa bellula clustered conspecifically during life.

The knowledge of fossil plant-insect interactions is almost entirely restricted to evidences of feeding behavior. Records of endophytic oviposition are relatively scarce, with previous earliest reports from the Middle to the early Late Triassic. Nevertheless, several Paleozoic insect taxa have been suspected of this reproductive behavior, but without any direct evidence. Specimens of Calamites cistii (Sphenophyta; Pennsylvanian, France) are described showing endophytic cavities, located in the outer cortex of the stem, a tissue that is rarely preserved. This new record shifts the appearance of this behavior back 60 Ma. Possible tracemakers are representatives of the Odonatoptera (Odonata and related extinct taxa), Palaeodictyopteroidea (extinct palaeopterous orders), and Archaeorthoptera (Orthoptera and related extinct orders). The antiquity of the insect endophytic oviposition behavior suggests that it could have been important during the emergence and diversification of the insect group.