A detailed sedimentological and paleontological analysis of the uppermost Miocene (Messinian)–Pliocene boundary at the northern border of the Bajo Segura Basin, southeastern Spain, was carried out in order to describe the evolution of the regional paleocoastline during the Pliocene reflooding of the Mediterranean immediately after the sea-level fall related to the Messinian Salinity Crisis. Multiple trace fossils typical of firm- and hardgrounds were recognized, allowing identification of Glossifungites (two different types), Entobia, and Gnathichnus ichnofacies. Trace-fossil analysis showed that lithology and media consistency exerted considerable control on the development of the different ichnocoenoses and that there was a clear decrease in hydrodynamic energy from a coastal to a shallow-water shelf environment related to progressive sea-level rise. Ichnological and sedimentological data provide evidence that the definitive flooding of the Mediterranean was rapid and synchronous throughout the northern margin of the Bajo Segura Basin. The following model for the Pliocene transgression in the study area is therefore proposed: (1) the marine ingression penetrated along the incised paleovalleys carved as a consequence of the fall in sea level, where the first two Pliocene systems were deposited (P0–P1); (2) during the maximum flooding surface of the transgression, the sea overflowed the margins of the paleovalleys and extended throughout the entire northern margin of the basin; and (3) the third Pliocene system was deposited, forming the lower part of a highstand systems tract (P2).

Paleoecological analyses conducted over broad temporal and spatial scales can incorporate fossil assemblages of disparate taphonomic histories, resulting in samples where the record of the original communities is biased to different degrees. Testing for the effects of differential taphonomic biases is crucial to accurate interpretations of paleoecological patterns. To test for such effects in a shallow-marine benthic foraminiferal record from the early Miocene Astoria Formation, I developed a taphonomic grading system for benthic foraminifera and scored individuals for preservation state. Grading allows each sample to be subdivided into taphonomically similar subsamples. Subsamples are evaluated for similarity in species composition, species rank, and proportional abundances. Similarities are significantly higher in within-sample comparisons between taphonomic grades than they are among samples when taphonomic grade is held constant, indicating that ecological information is conserved despite variation in taphonomic grade within a single time-averaged assemblage. In addition, taphonomically homogenous subsamples (and nested sets of taphonomic grades) capture the same temporal patterns of species richness, community evenness, and the proportional abundances, although ordinations using subsamples with the poorest preservation do show some significant differences. Thus, although incorporating the most poorly preserved samples requires some caution, the quality of ecological information derived from these benthic foraminiferal samples is consistent across taphonomic grades. For this test case, I argue that paleoecological analyses will not be significantly affected by differences in preservation among samples. This method of taphonomic grading can be applied to other fossil groups and facilitates analyses of paleoecological results despite different degrees of taphonomic alteration.

We report a coral-sponge dominated reef lithofacies in detrital boulders of carbonate-clast conglomerate from the Olds Ferry terrane, Blue Mountains Province, Willow Spring locality, northeastern Oregon. This discovery constitutes the first report of Triassic reefal lithofacies from the Olds Ferry terrane. Corals at the site include a high-growing, dendroid-phaceloid species that acted as a framework or sediment baffle, and a low-growing, cerioid, encrusting coral and a sponge that acted as sediment binders. The co-occurrence of coral taxa in the Wallowa intraoceanic arc and Olds Ferry pericratonic arc terranes suggests that during the Late Triassic, these regions were in proximity to one another. With this report, Upper Triassic carbonate rocks are known from all of the major terranes of the Blue Mountains Province and a Tethyan affinity is established for the fauna of the Olds Ferry terrane. We suggest that the source of this Late Triassic coral-sponge reef fauna in the upper member of the Huntington Formation was intrabasinal and that the source rocks are no longer exposed in the region. Numerous possible regional source areas for these detrital limestone clasts rule out the need to call upon an exotic terrane source area.

This study records the different types of trackways produced by the freshwater crayfish Orconectes in a controlled environment. Different trackway morphologies were created through the variation of media ( = substrates) grain size, moisture level, and surface inclination in terrestrial and subaqueous settings. Sediment was sieved into clay and silt, very fine-, fine-, and medium-grained sand. A rectangular container filled with sediment was used to run trackway trials on flat and 10° inclined surfaces. All subaqueous tracks were made in a container on a flat surface. Moisture content for the terrestrial trials was determined by removing a sample of moistened sediment, weighing it before and after heating in an oven for 24 hours, and recording the values in percent water weight. Media moisture content had the greatest effect on trackway characteristics. Trackway preservation of individual appendage marks decreased as grain size and moisture content increased; dry clay and silt preserved the most detailed trackways. Intermediate moisture levels created a firm surface that decreased trackway preservation. Crayfish movement through soupy sediment produced continuous furrows to a depth of 1 cm. Trackways of crayfish moving up and down the inclined surface had shorter stride lengths than those made of a flat surface. Subaqueous trackways in fine- and very fine-grained sand preserved the clearest, most consistent trackways. Results from this study can be used to (1) identify trackways of ancient crayfish and (2) infer the relative amount of moisture present at the time the trackway was produced.

The presence, distribution, and preservation of coral-rich facies in the lower Oligocene Gornji Grad Beds of Slovenia are analyzed using a microtaphofacies approach. This method allows taphonomic signatures to be recognized in thin section along with the presence of coral specimens and growth forms within and between stratigraphic logs. Coral-dominated limestones within the Gornji Grad Beds are represented by rudstones in a packstone-wackestone matrix. The conditions are generally reconstructed as turbid water due to the prevalence of muddy carbonate matrix, which also leads to excellently preserved morphological features in thin section. These beds represent a reference area for the study of Paleogene corals, especially during the Oligocene, a key phase of reef development during the Cenozoic. This study also contributes to the characterization of fossil reefs in turbid-water environments. The evaluated coral fauna is dominated by delicate-branching Stylophora and Acropora, although thickly branching (Actinacis, Goniopora), phaceloid (Caulastrea), and massive forms (Alveopora, Astreopora, Antiguastrea) also occur. Assessed taphonomic signatures include fragmentation, abrasion, bioerosion, and encrustation. Three types of bioerosion traces are distinguished (Entobia, Gastrochoenolites, Trypanites). Encrustation incl udes both thin crusts and complex multi-taxon sequences dominated by coralline algae. Five microtaphofacies are distinguished based on variation of taphonomic signatures, taxonomic composition, and growth forms. Differences in microtaphofacies are interpreted with respect to turbidity, sediment accumulation, and water turbulence; both parautochthonous and allochthonous deposits are reconstructed. A depositional model based on the distribution of microtaphofacies in the studied sections shows a succession of coral communities with different colonization strategies reflecting generally high stress levels.