French and North American cherts used for millstones during the late eighteenth century and nineteenth century in Ohio are generally similar in color, hardness, presence of cellular porosity, and other characters. Although basic differences in fossil content and geologic age have been known since the 1830s, and previous authors have noted the presence of fusulinids and other fossils in Ohio buhrstone, and charophytes as well as gastropods in millstone pieces found in New England but imported from France, little attention has been paid to the fossil content of chert millstones in the United States. We document examples of chert millstones in Ohio, distinguishing cherts (French buhr) imported from the Tertiary of France for use as millstones from local Pennsylvanian cherts (buhrstone) used for millstones. French buhr (known as meulière in France), from the Tertiary deposits of the Paris Basin, contains gyrogonites belonging to the Oligocene species Gyrogona medicaginula, charophyte thalli, and freshwater gastropods. The fossil content of the Ohio cherts, as observed in millstones, is diverse, including Pennsylvanian (late Carboniferous) marine fossils, notably fusulinids, pelmatozoans. and brachiopods. The concepts and examples described in this paper are broadly applicable outside of Ohio as millstones made of Ohio chert were exported outside of Ohio to other states, and French millstones have been distributed worldwide, so these concepts can be applied to study of millstones (as well as other chert objects), found outside of North America as well. This study also serves as another example of the usefulness of steinkerns and molds of gyrogonites in identification of charophyte species.

Carnian and Norian (Upper Triassic) limestones and dolostones along the Eisriesenwelt trail on the Tennengebirge (Salzburg, Austria) reveal a progression from fore-reef to lagoonal environments, including a small Norian reef with both Carnian and Norian characteristics. Here, we provide high-resolution biostratigraphic age constraints of the Tennengebirge platform carbonates and describe an early Norian patch reef that is built by large Retiophyllia corals and encrusted by “Tubiphytes,” sponges, and microbial fabrics. The tall (up to 4 m), narrow phaceloid Retiophyllia coral colonies exhibit phototropic growth patterns—coral branches that are at the top of the colony grew longer than those on the side of the colony—thus, we suggest that these corals had a symbiotic association with photoautotrophs (most likely zooxanthellae). The well-constrained ammonoid and conodont biostratigraphy presented here establish that the Tennengebirge patch reef was deposited in the early Norian, nevertheless, it contains features typically associated with Carnian reefs (small, encrusting sponges, Carnian-style microbial crusts, and “Tubiphytes”). The Carnian traits of the Norian reef emphasize the importance of accurate biostratigraphic dating; obtaining independent age estimates for reef outcrops is crucial to correctly determine the timing and magnitude of transitions in Triassic reef ecology.

Benthic foraminifera are common and distinct elements of Late Triassic reefs. It has been observed that different subenvironments of carbonate platforms contain different associations. These, however, have never been a focus of a taphonomic study. The assessment of taphonomic processes affecting benthic foraminifera along a transect of the Rhaetian reef-rimmed platform on Mount Begunjščica in Slovenia is based on thin-section analyses. The foraminiferal assemblage of the open lagoon consists primarily of autochthonous and parautochthonous specimens. Boring into the tests' interior and cyanobacterial encrustation are characteristic of areas with low sedimentation rates. Foraminifera found in tidal-inlet channels transecting the lagoon were accumulated from adjacent subenvironments and are characterized by abrasion. Back-reef sand and interstices of the lithoclastic rudstone of the central-reef area contain the most diverse foraminiferal assemblages, consisting of mixed parautochthonous and allochthonous specimens. Whereas back-reef sandstone beds contain species typical for the back-reef and the central-reef areas, the central-reef breccia contains a distinctively high proportion of Galeanella, Decapoalina (former “Sigmoilina”), and Alpinophragmium. Understanding the post-mortem processes that modified foraminiferal taphocoenoses allows us to consider these factors in future paleoecological studies of Late Triassic foraminifera.

Dozens of well-preserved fossil burrow systems in upper Miocene sedimentary rocks of the Ogallala Group at a site in east-central Nebraska record rodent behavior and the subsurface ecology of grasslands just as the modern Great Plains was developing. These burrow systems include one to four entrance or exit tunnels, large underground nesting chambers at depths of several decimeters below ancient land surfaces, and incisor grooves on the walls. Tunnels average 89.8 mm in diameter, a value similar to the burrow diameters of multiple living North American rodents. Chambers vary in shape and typically exceed 500 mm in length; some attain 1000 mm in length. Living marmotine ground squirrels (tribe Marmotini) construct burrow systems of varying degrees of complexity, but they do not engage in shallow subsurface foraging. Extinct members of this group were the most likely excavators of the fossil burrows. In contrast, extant pocket gophers (family Geomyidae) and, presumably their fossil relatives, are obligate subterranean animals that produce linked deep and shallow burrow subsystems, the latter representing their chief foraging strategy. Our results raise issues regarding the relationships between the architecture of fossil rodent burrow systems and aspects of rodent behavior and life history, such as litter size, developmental rates, seasonal torpor, hibernation, and sociality in grasslands. An improved understanding of the burrowing behaviors of ancient rodents will highly complement the growing body of knowledge about the development of grasslands on Earth over time, but truly ichnological analyses of the burrows and burrowing behaviors of extant rodents are much needed.

Intervals of faunal turnover in the fossil record are often preserved at unconformities, suggesting that their apparent abruptness is an artifact of geologic discontinuities. A detailed investigation of the Middle Devonian Kačák Bioevents of the Appalachian Basin focused on stratigraphically complete sections of eastern New York State to further elucidate the nature and timing of faunal turnover where not cloaked by an unconformity. The Lower Kačák Bioevent is fairly well constrained to the lower portion of the East Berne Member of the Mount Marion Formation. The Upper Kačák Bioevent is less well constrained to within the middle to upper East Berne Member, however. A thorough dissection of the East Berne Member has yielded the more precise timing of the initial Hamilton Fauna incursion, occurring at the level of the thin, fossiliferous, Dave Elliot Bed (DEB). The occurrence of the goniatite Tornoceras aff. mesopleuron below the DEB constrains the Hamilton incursion to the earliest Givetian age. The DEB fauna is composed of a single taxonomic holdover from the older Stony Hollow Fauna, while the entire rest of the DEB fauna carries over into the remaining Hamilton E-E (ecological–evolutionary) subunit. From the data at hand, this faunal incursion does not represent a gradual or step-wise incursion. When studied in the thickest, most conformable, stratigraphically complete sections preserved, this incursion occurs as an abrupt event. The pattern of faunal change preserved is a two-step extinction and turnover, with extinction occurring at the onset of dysoxic flooding (Lower Kačák Bioevent), followed by the rapid incursion of new fauna associated with sea-level fall (Upper Kačák Bioevent) in the area under consideration.

Ensis americanus (Binney) is an alien razor shell living infaunally in the southern North Sea. It is encrusted postmortem by the acorn barnacle Balanus crenatus Brugière. A remarkable shell of E. americanus was found densely infested by a single spatfall of B. crenatus on the inner and outer surfaces of both valves. The ligament was still attached and was pliant when collected, indicating that infestation was soon after death, probably only weeks or months before it was collected. The evidence of this specimen argues strongly against the common received wisdom that borings or encrustations on the inner surfaces of disarticulated fossil bivalves are an indication of a relatively long postmortem residence time on the seafloor.

Oyster–microbial rolling stones (ostreoliths) from the Upper Jurassic (Kimmeridgian) of Sulejów and Małogoszcz, Poland, are described and interpreted in terms of their origin and development. The ostreoliths are composed mainly of small-sized oysters (Nanogyra nana) that initially encrusted bivalve or ammonite shells. These structures were frequently overturned during their further growth by hydrodynamic agents. The oyster shells are covered by a thin crust that is suggestive in appearance of a microbial mat. We postulate that the mats not only bound the shells, but also induced early cementation of the sediment infill, thereby triggering the rapid lithification and rigidity of ostreoliths. This interpretation is supported by the presence of bivalve borings that cut the shells, microbial crust and internal sediment infill. The oyster–microbial association provided favorable conditions under which hardground biota thrived in a soft-bottom setting which was otherwise inimical to such organisms. These hardground biota are represented by a variety of encrusters (foraminifera and foraminifera-like problematica, plicatulid bivalves, cyclostome bryozoans, serpulids, and thecideid brachiopods) and borers (bivalves, bryozoans, and phoronids). Ostreoliths from Sulejów are of smaller size, and with a less-developed oyster cortex, than those from Małogoszcz. This may be due to a higher frequency of physical disturbance (storms) at Sulejów which halted ostreolith development at earlier phases than at Małogoszcz. A large oyster buildup recorded previously from Brzegi, close to Małogoszcz, suggests that, under favorable conditions, ostreoliths could eventually have transformed into stationary, patch-reef–type structures.