We studied the rapid paleo-environmental changes and the corresponding biotic responses of benthic foraminifera of a shallow shelf site during the late Paleocene and the Paleocene-Eocene Thermal Maximum (PETM). The PETM is globally characterized by a negative δ13C excursion in marine and terrestrial sediments. Isotope data from the Atlantic Coastal Plain from the South Dover Bridge core, Maryland, show an additional small δ13C excursion just below the base of the PETM: the “pre-onset excursion” (POE). The benthic foraminiferal and coupled grain-size record of the late Paleocene indicates a well-oxygenated, current-dominated environment with a stable, high food supply. During the POE, bottom currents become subdued and finer-grained sediment accumulation increased. These changes are partially reversed after the end of the POE. Before the PETM the river influence increases again, food supply becomes more pulsed and the benthic taxa, typically connected to the PETM, start to appear in those gradually warming conditions. During the PETM, the environment shifts to a river-dominated one, with strongly reduced currents. The low-diversity PETM fauna thrives under episodic low-oxygen conditions, caused by river-induced stratification, while the Paleocene assemblage nearly vanishes from the record. Gradually the environment begins to recover, the grain size shows an uptick in bottom currents and pre-PETM foraminifera become more abundant again, indicating increased oxygen levels and a more stable food supply. While the overall environmental shifts at South Dover Bridge fit within the observations across the shelf, the POE related insights are so far unique. Our bathymetric reconstructions show an outer neritic paleodepth (∼100 m) during the Paleocene, with a modest sea level rise in the core phase of the PETM, which is subsequently reversed during the recovery phase.

The Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) is the most pronounced recorded Cenozoic hyperthermal event, punctuating the long-term warming trend of the early Paleogene with global temperatures increasing by 5–8°C (Kennett & Stott, 1991; Zachos et al., 2006, 2008; Dunkley Jones et al., 2013; Westerhold et al., 2020). The PETM is characterized by a negative δ13C excursion in marine and terrestrial sediments, likely caused by a large injection of isotopically light carbon into the atmosphere (McInerney & Wing, 2011) as well as a negative δ18O excursion indicative of global warming (Kennett & Stott, 1991). Resultant environmental changes triggered major biotic reactions in the marine biosphere, including the appearance of distinct excursion taxa, and extinction of taxa—most notably in the deep-sea benthic foraminifera (Thomas, 1998; Sluijs et al., 2007a; McInerney & Wing, 2011; Speijer et al., 2012; Tian et al., 2021). In the U.S. Atlantic Coastal Plain (ACP), the PETM is marked by the unusually thick (up to 10–16 m) silty-clayey sediment package known as the Marlboro Clay and continues into the basal part of the Nanjemoy (Maryland, Virginia) or Manasquan (New Jersey) formations (Fig. 1B; Gibson et al., 2000; Stassen et al., 2015; Rush et al., 2021). Deposition of the Marlboro Clay occurred in a mid-latitudinal, middle to outer neritic shelf (50–200 m; Stassen et al., 2015; Robinson & Spivey, 2019) setting with input from multiple large river-systems from the west and north, with the largest being the paleo-Potomac river system (Kopp et al., 2009; Stassen et al., 2015; Robinson & Spivey, 2019). The Marlboro Clay has a high kaolinite content (20–60%), relative to the Paleocene Aquia and Vincentown formations (<10%; Gibson et al., 2000; Doubrawa et al., 2022). The sedimentary architecture of the PETM from the New Jersey area has been interpreted as progradating clinoform foresets in response to the high riverine input onto the shelf (Podrecca et al., 2021). A likely enhanced hydrological cycle during the PETM led to an increased input of freshwater, sediment loads, and food supply into the shelf (Zachos et al., 2006; Kopp et al., 2009; Rush et al., 2021). Oceanic and climatic perturbations connected to the PETM—such as rapid warming of the water column, decreasing pH, intensification of the hydrological cycle, or a sea level increase—are reported in detail from across the region (Zachos et al., 2006; Sluijs et al., 2007a; Kopp et al., 2009; Harris et al., 2010; Self-Trail et al., 2012; Babila et al., 2016; Makarova et al., 2017; Rush et al., 2021).

While many studies have focused on the northern part of this shelf in New Jersey, and detailed environmental reconstructions based on foraminifera are available (Stassen et al., 2012a, 2015; Babila et al., 2016; Makarova et al., 2017; Livsey et al., 2019), similar studies of the Maryland sites are limited. Previous work from Maryland focused on geochemical records, cyclostratigraphy, nannofossils, and foraminifera of the PETM and associated environmental changes during this warming event (Self-Trail et al., 2012, 2017; Robinson & Spivey, 2019; Li et al., 2022). The enhanced sedimentation rates of the Paleocene-Eocene transition make the ACP an ideal region for stratigraphic studies (Babila et al., 2022; Doubrawa et al., 2022; Li et al., 2022). For this study, we analyzed sediments from the South Dover Bridge (SDB) core, Maryland (Fig. 1A). Previous planktic and benthic foraminiferal studies from this site focused on the upper Paleocene sediments and the lowermost 4 m (204–200 m) of the Marlboro Clay and thus the beginning interval of the PETM, using the >125-µm fraction of foraminifera (Robinson & Spivey, 2019). Here we expand their work to the upper end of the PETM interval (Paleocene: 210–204 m, PETM: 204–189 m core depth). Additionally, the >63-µm size fraction was examined for benthic foraminifera in order to include smaller taxa.

Isotopic data from SDB show a small (1–1.5‰), but distinct, δ13C excursion in a more clay-rich interval just below the PETM, the so-called “pre-onset excursion” or POE (Lyons et al., 2019; Babila et al., 2022; Doubrawa et al., 2022). The presence of the POE indicates that environmental perturbations during the Paleocene-Eocene (P-E) transition, such as oceanic acidification or changes in the hydrological cycle (Ridgwell & Schmidt, 2010; Babila et al., 2016), were not confined to the PETM (Babila et al., 2018). We use high-resolution benthic foraminiferal abundance and grain-size data to trace the evolution of the shelf environment in detail from the POE and across the PETM at SDB and correlate it with the northern New Jersey sections.

The PETM of the Maryland and New Jersey sites is represented predominantly by the Marlboro Clay, a clayey-silty sediment package with thickness between 1.5–15 m (Doubrawa et al., 2022) that was influenced by riverine input, paleodepth, as well as erosion and truncation. The Marlboro Clay overlies the upper Paleocene Aquia Formation, a medium to coarse, glauconitic-rich silty sand that extends from Virginia and into Maryland (Nogan, 1964; Drobnyk, 1965; Self-Trail et al., 2023). The Vincentown Formation is age equivalent to the Aquia Formation and was deposited in New Jersey (Nogan, 1964; Gibson et al., 2000). The SDB core was drilled in 2007 by the U. S. Geological Survey (Fig. 1A) and is located in the central Salisbury Embayment of Maryland, USA (38°44′49″N, 76°00′25″W). South Dover Bridge was situated at middle to outer neritic depths (Self-Trail et al., 2012; Robinson & Spivey, 2019). The large paleo-Potomac river system emptied into the paleo-shelf ∼100 km west of SDB.

Bulk and foraminiferal δ13C records from the region for the upper Paleocene Aquia sediments are relatively stable, having values from ∼0–1‰, depending on proximity to the coast (Doubrawa et al., 2022). Latest Paleocene sedimentation rates were low, ranging from 0.1–2.4 cm/kyr across the region (Stassen et al., 2012b; Doubrawa et al., 2022). In the Aquia Formation, the POE is well defined by a carbon isotope excursion of ∼ −2‰, recorded in the bulk and foraminiferal record (Self-Trail et al., 2012; Babila et al., 2022; Doubrawa et al., 2022). It is additionally characterized by an interval of finer-grained sediments (∼1.5 m) somewhat similar to the PETM Marlboro Clay, but the POE exhibits a low kaolinite content, as opposed to the high kaolinite content of the Marlboro Clay (Doubrawa et al., 2022). On the ACP, the PETM is marked by a δ13Cbulk and δ13Cforam excursion of ∼ −4 to −6‰ (Self-Trail et al., 2012; Stassen et al., 2012b; Doubrawa et al., 2022). Stratigraphically, the Carbon Isotope Excursion (CIE) is divided into a core phase (lowermost δ13C values after onset) as well as recovery phases 1 (initial rapid rise of δ13C) and 2 (slower rise of δ13C; Röhl et al., 2007). Recovery phase 2 at SDB is truncated by an unconformity cutting the PETM section short at ∼115 kyr post onset, and marking the transition to the Eocene Nanjemoy Formation (Self-Trail et al., 2012; Doubrawa et al., 2022).

Fifty-five sediment samples were analyzed for benthic foraminiferal content, spanning from the uppermost Paleocene through the PETM. The dried samples were weighed, soaked in distilled water, and gently washed over >63-μm sieves. Subsequently, they were dried in a dryer oven at 40°C. Six samples from the CIE onset interval were barren or nearly barren of foraminifera. Using an ASC microsplitter, representative splits of ∼300 benthic foraminifera per sample were picked, sorted, and mounted on glued Plummer slides. Taxonomy from Nogan (1964), Kellough (1965), Fenner (1976), Gibson et al. (1993), and Stassen et al. (2015) was used to identify the benthic foraminiferal species. Raw counts of the full assemblage data appear in Table A1.

Grain-size data of the non-calcareous, lithic fraction was obtained by measuring 77 samples with a LS13 320 Beckman Coulter Laser Diffraction Particle Size Analyzer (Earth and Environmental Sciences Department, KU Leuven). Prior to the analyses, samples were manually disaggregated and treated with HCl and H2O2 to remove calcareous components and organic matter. The grain-size terminology follows Wentworth (1922). While we represent the data in the phi scale, we also calculated the natural logarithm (LN) of (<10 µm/>10 µm) (LN(f/c)), to gain representation of the shifts in finer-grained versus coarser-grained sediments. The finer group contains clay and fine silts (<10 µm), indicative of a low-energy depositional environment. The coarser fraction (>10 μm) comprises the non-cohesive acting silt and sand fraction commonly indicative of a relatively higher energy environment (McCave et al., 1995).

A total of 81 species of benthic foraminifera were identified. Pictures were taken on a SEM Jeol JSM-6360 with Au-coating, and with a Dino-Lite camera on a Leica 10450028 microscope. The 22 taxa comprising more than 2.5% in more than one sample are included in the graphs and discussion. To prevent information loss in resultant associations, taxa with low numbers were grouped at the genus level. Gyroidinoides aequilateralis and G. subangulatus were grouped into Gyroidinoides spp.; Cibicidoides neelyi, C. irenae, C. succedens, and C. marylandicus were grouped into Cibicidoides spp. Minorly present agglutinated species and fragments were also grouped together. All species data were used to determine foraminiferal numbers (individuals >63 µm per gram of sediment, for benthic and planktic foraminifera) to check for condensed horizons and to calculate diversity indices based on benthic foraminifera (Fig. 2; Fisher Alpha (α), and Shannon H(s) indices). For statistical analyses, PAST3 software was used (Hammer et al., 2001). A hierarchical cluster analysis using Pearson distance measurements was performed on the abundance data to compare benthic foraminiferal data (Fig. 3). The resulting associations indicate similar environments, allowing a grouping without information loss. Representative taxa from the associations are illustrated in Figures 47 and Figures A1A4. A Detrended Correspondence Analysis (DCA) was conducted to gain statistical insight into environmental conditions of the obtained clusters (Fig. 9). The “rest and indet.” group contains rare taxa and indeterminant (fragmented, partly dissolved) foraminifera that could not be assigned to a specific taxon.

Foraminiferal data were used to obtain paleodepth estimates (Fig. 3). On a shelf with a diverse benthic foraminiferal assemblage, the relative abundances of the species associations can be used to calculate paleodepth estimates based on the equation:
formula
proposed by Stassen et al. (2015), where ni equals the percentage of association i, depthmin and depthmax equal upper and lower limit of preferred water depth of association i. We applied the same approach on a species level, using the percentage and the upper and lower depth limits of each species in order to obtain a weighted estimate, minimizing the effect of uncommon species with large depth ranges. The respective reported water-depth preferences of these mostly extinct species are based on western Atlantic Paleocene and Eocene shelf faunas from the Wilson Lake, Bass River, Clayton, and Mattawoman Creek drill cores, the Cabin Creek and Aquia Creek sites (ACP), the Cannonball Formation (North Dakota), and the Wills Point Formation (Texas) (Nogan, 1964; Kellough, 1965; Fenner, 1976; Gibson et al., 1993; Stassen et al., 2015; Self-Trail et al., 2017; Robinson & Spivey, 2019). These water depth estimates have a large uncertainty due to the often wide or overlapping depth range of benthic foraminifera on the shelf.

Foraminiferal Associations and Diversity Trends

Benthic and planktic foraminifera occur in most samples, and preservation is good (Paleocene interval) to excellent (PETM interval), except for six barren samples from the lowermost Marlboro Clay above the CIE onset. The coarser-grained uppermost Paleocene samples contain ∼1000 benthic foraminifera per gram, with peaks pre- and post-POE reaching >5000. Benthic foraminiferal numbers are higher during the PETM interval, averaging about 2500 foraminifera per gram during the CIE core, with peaks during the recovery phase reaching >7000 (Fig. 2). These values exceed reported average values for the P-E intervals in New Jersey (Wilson Lake: ∼500, Bass River: ∼2000; Stassen et al., 2015). The Fisher α diversity index is highest during the Paleocene interval but shows a decreasing upward trend and an additional reduction above the barren interval (Fig. 2). The index shows a second peak in the POE interval, while in comparison, the Shannon (H) index is relatively stable throughout the Paleocene, with a decline above the barren interval. For both indices the diversity is lowest throughout the CIE core phase. During the CIE recovery, the diversity indices increase again but do not return fully to Paleocene levels, though peaks do reach them.

The cluster analysis resulted in three major associations that can be further subdivided into two groups a and b, based on the similarity (Table 1, Fig. 3). Association 1a is the most diverse association and dominant in the uppermost Paleocene sediments. Predominant species in this group are Pseudouvigerina triangularis, Cibicidoides alleni, C. howelli, and Anomalinoides compressus, ranging from ∼40% at the lowermost studied part of the core to up to ∼85% at the onset of the POE, before declining towards the barren interval marking the base of the PETM (Fig. 3). Some species of association 1a show decreasing abundances starting from the beginning of the POE, either fully vanishing before the end of the POE (Bolivinopsis emmendorferi), or distinctly declining towards the PETM (e.g., P. triangularis, C. alleni). The other taxa of association 1a remain consistently present up to the base of the PETM, where they vanish at the dissolution horizon or just above it. This pattern can be seen for all Cibicidoides species, Anomalinoides compressus, and Epistominella minuta—the latter showing a distinct increase above the POE. In the PETM interval, association 1a is present in low numbers (<5%) and only a few taxa reappear in very low abundances in the PETM CIE recovery phases, composing abundances of ∼10% below the unconformity truncating recovery phase 2. Association 1b consists solely of Paralabamina lunata (Fig. 3). It represents ∼20% of the Paleocene assemblage, in which it is a consistent component, with a slight decrease towards the POE. Above the POE, it increases to its highest percentage of ∼30%. During the core phase, it is a minor component of the assemblage, reappearing just below the transition to the recovery phase in which P. lunata increases again to ∼20%.

Association 2 is present in relatively consistent abundances throughout the whole studied interval. Association 2b is dominated by Bulimina virginiana, with abundances of 30–40% in the Paleocene interval. At the onset of the POE, B. virginiana is present at only ∼5%, before increasing again throughout the POE. Percentages decrease to 10–20% in the core section of the PETM, but gradually increase again during the recovery phase (∼40% below the unconformity). Association 2a species Valvalabamina depressa constantly represents <10% of the whole assemblage, vanishing only in the lowermost part of the core phase, where a barren interval exists.

Association 3 taxa are absent in the Paleocene or only appear in low numbers near the POE interval. Taxa of 3a are partially present in the Paleocene, and appear more, but still in very low numbers in during the PETM. Three taxa of association 3b (Pulsiphonina prima, Anomalinoides acutus, and Pseudouvigerina wilcoxensis) dominate the lower diverse assemblage of the PETM section. Association 3b makes up to 90% in the initial phase of the PETM, before decreasing gradually throughout the core and recovery phase. Pseudouvigerina wilcoxensis shows a slightly different pattern, with increasing numbers throughout the core phase and disappearing in the recovery phases.

Grain Size Variations

The studied interval covers the uppermost Paleocene Aquia Formation (209–204 m), the PETM associated Marlboro Clay, and the Eocene Nanjemoy Formation, above the unconformity at ∼189 m (Alemán González et al., 2012). The Aquia Formation consists of sorted glauconitic siliciclastic sediments, dominated by fine sand and coarse silt. The pre-POE interval has a well-developed unimodal grain-size distribution with a peak at ɸ = 3–4 (Fig. 8) and a modest clay component (∼15%). Within the POE, the clay to fine silt content slightly increases as well as the medium to coarse sand fraction, but still with a distribution curve with a concise 3–4ɸ peak. The post-POE grain-size spectrum shifts to decreasing fine sand content, while the medium to coarse silt component increases, before shifting towards a multimodal shape during the transition to the Marlboro Clay. Gradation into the Marlboro Clay is visible in two samples just below the contact, where silts increase and the sediments display a more homogeneous distribution. The Marlboro Clay exhibits an increase in clay and fine silt with a broad, multimodal distribution. This distribution persists throughout the core phase and recovery phase 1 (Fig. 8). In recovery phase 2, there is a coarsening upwards trend, and the grain-size starts to shift back towards a coarse silt and increasingly fine sandy suite, with the distribution curve becoming more bimodal in shape. The latter also contains large glauconitic particles and is siltier compared to the Aquia Formation.

Paleodepth Estimates Across the P-E Transition

The paleodepth estimates based on benthic foraminiferal associations suggest an overall consistent paleodepth of ∼100 m throughout the studied interval, with a shallowing of about 5 m towards the onset of the POE (Fig. 2). The taxa-based estimates show a little more variation, with a shallowing to ∼80 m observed below the POE, followed by a deepening to ∼100 m in the latest Paleocene. A minor increase of ∼10 m in paleodepth is noted in the PETM CIE core phase. The depth estimates based on associations including and excluding the opportunistic taxa group typical for the PETM (association 3) show no distinct water depth changes throughout the whole studied interval (Fig. 2).

Detrended Correspondence Analysis (DCA)

We plot the first and second DCA loadings in a bivariate plot in order to establish the faunal and environmental developments (Eigenvalues: axis 1 = 0.6082, axis 2 = 0.0615; Fig. 9). The DCA shows a clear separation of associations 1, 2, and 3 along axis 1 (Fig. 9A). The larger, mostly epibenthic (Kaiho, 1994; Stassen et al., 2015) species of association 1 (Fig. 2; Table 1) plot on the lower end of axis 1. Cibicidoides spp. and Bulimina hornerstownensis are typical of well-oxygenated environments (Gibson, 2001; Alegret et al., 2003; Stassen et al., 2015). Loadings of association 3 species plot on the higher end of the x-axis. These taxa—Pulsiphonina prima, Anomalinoides acutus, and Fursenkoina wilcoxensis—were known to have survived, or even thrived, under low-oxygen conditions and/or temporary anoxia (Speijer et al., 1996; Gibson, 2001; Stassen et al., 2015). Association 2 species plot in-between association 1 and 3. Bulimina virginiana, a thin-walled endobenthic foraminifera, is associated with low oxygen conditions when food availability is high (Stassen et al., 2015; Self-Trail et al., 2017). Valvalabamina depressa and Tappanina selmensis are also reported from environments with moderate to low oxygen levels (Speijer & Van der Zwaan, 1996; Stassen et al., 2015; Self-Trail et al., 2017). The distribution suggests that axis 1 is indicative of oxygen levels, with association 3 species at the low end of seafloor oxygenation and association 1 species indicating highest oxygen levels.

Along axis 2 (Fig. 9A) subgroup 2a plots on the higher end, 2b and 3a on the lower end, and 3b on both ends. Species P. prima and A. acutus deviate from this pattern, plotting on the lower end. Taxa from association 1a are distributed equally along axis 2, with their relative value reflecting the stratigraphic interval of their disappearance. Species which disappear from the assemblage during the POE plot lower, and taxa vanishing with the onset of the PETM plot higher on the axis. The taxa plotting on the higher end of the axis 2 are indicative of elevated food levels (Pseudouvigerina wilcoxensis) but were also known to survive on episodic food fluxes (Epistominella minuta and Valvalabamina depressa; Gibson et al., 1993; D’haenens et al., 2012; Self-Trail et al., 2017). Most taxa plotting on the lower end of the axis 2 prefer an environment with a constant, moderate to high food input (Cibicidoides spp., Bulimina spp., and Tappanina selmensis; Clemmensen & Thomsen, 2005; Stassen et al., 2015; Self-Trail et al., 2017). This suggests food supply as the driving factor for axis 2 distribution, with a continuous food source being on the low end and a more pulsed food input on the higher end.

The corresponding sample scores of the DCA, plotted as the sample depths in a bivariate plot, show a clear distinction of PETM samples and Paleocene samples along axis 1 (Fig. 9B). Axis 2 does not separate groups as distinctively. The Paleocene samples show a rough trend from pre-POE samples with the lowest scores, to POE samples with medium scores, to post-POE samples with the highest. The POE and pre-POE samples show a large overlap, while the post-POE samples plot distinctively separate from the previous two groups. The PETM core samples span the entire axis 2. Samples from the lower part of the core phase (∼202.6–200.6 m), cluster in the lower end of the axis, while the upper samples from the core phase have higher scores on axis 2 values. Samples from recovery phases 1 and 2 show a decreasing trend in x-axis values towards pre-PETM samples.

Latest Paleocene Background Environmental Conditions

Overall, the uppermost Paleocene interval at SDB is characterized by a moderately diverse benthic assemblage, with a constantly high diversity compared to the succeeding PETM interval (Fig. 2). Most taxa of association 1a are characteristic dwellers in Paleocene shallow-shelf assemblages of the ACP (Gibson et al., 1993; Gibson, 2001; Stassen et al., 2015; Robinson & Spivey, 2019). The most dominant taxa in association 1a belong to the genus Cibicidoides (e.g., C. alleni and C. howelli). They are common in the deep inner to outer shelf with an epibenthic lifestyle and typically are reported from moderate to high oxygen conditions (Fig. 10; Kaiho, 1994; Gibson, 2001; Alegret et al., 2003; Clemmensen & Thomsen, 2005). At Wilson Lake, Cibicidoides spp. make up similar proportions to those at SDB, C. alleni starts to decline before the PETM (Stassen et al., 2015) in an interval which has been suggested to be the equivalent interval of SDB’s POE (Doubrawa et al., 2022). The abundances of C. howelli at SDB and Wilson Lake both increase in the uppermost interval before the PETM. Cibicidoides howelli is rare at the Bass River and Mattawoman Creek sites, where paleodepth estimates are deeper and shallower, respectively, than those at SDB. Cibicidoides alleni is missing from the Mattawoman Creek record (Robinson & Spivey, 2019) and rare at Bass River (Stassen et al., 2015). In all records, other taxa indicate moderate to high oxygen levels in the bottom waters, such as Lenticulina spp. and Epistominella minuta at Mattawoman Creek (Robinson & Spivey, 2019) or Paralabamina lunata at the New Jersey sites (Stassen et al., 2015), excluding a strong oxygen gradient as a factor for the variable distribution of Cibicidoides species. Similarly, Anomalinoides compressus is absent in low-oxygen conditions, but more common in intervals of normal productivity and salinity (Gibson et al., 1993; Edwards, 2001). This may suggest that depth variation could have controlled the differences in distribution of Cibicidoides spp., with Mattawoman Creek being too shallow and Bass River being too deep for C. howelli to thrive.

Bulimina virginiana (association 2b; Robinson & Spivey, 2019; Stassen et al., 2015) and large Pseudouvigerina species (association 1a; Gibson et al., 1993; Stassen, et al., 2012b), indicating a high and continuous food supply, are common. At SDB, B. virginiana is dominant (20–40%), similar to the New Jersey site Wilson Lake (30–50%), but clearly differing from Bass River (<5%). This likely is due to different trophic levels, which were influenced by riverine input (D’haenens et al., 2012; Stassen et al., 2015; Self-Trail et al., 2017). The decrease in abundance below the POE could be related to the parallel decrease of pH at the sea floor (Babila et al., 2022). Diversity is relatively high within the SDB sequence, indicating living conditions with oxygen (Sen Gupta & Machain-Castillo, 1993) and food levels (Jorissen et al., 1995, 2007) high enough to sustain a broad assemblage of benthic foraminifera. To summarize, the benthic foraminiferal fauna indicate sufficiently oxygenated seafloor conditions with a moderate to high continuous food supply (in accordance with the interpretations of the DCA axes; Fig. 9).

The upper Paleocene Aquia Formation in Maryland, and corresponding Vincentown Formation in New Jersey, consist of glauconitic sands (Cramer et al., 1999; Kopp et al., 2009; Self-Trail et al., 2017). At SDB, the upper Paleocene samples are dominated by coarse silt to sand-sized fractions; pre-POE samples display a unimodal grain-size distribution of moderately sorted fine sand, with low proportions of finer-grained material. This likely relates to a single sediment source and a depositional environment with continuous reworking of sediment in a storm-dominated environment (Fig. 8; Drobnyk, 1965; McLaren, 1981; McCave et al., 1995). Storm wave bases can reach deep enough (30–50 m commonly in modern settings, but reportedly can exceed 100 m) to influence a middle neritic setting, like SDB, with strong storms and hurricanes inducing bottom currents causing resuspension and scouring of the sea floor (Immenhauser, 2009; Peters & Loss, 2012). This, together with possible offshore currents parallel to the coast, may cause winnowing of finer sediments, leading to a slow build-up of coarser sediments with smaller, thin-walled foraminifera and other organisms often being broken and carried away. While this potential loss of thin-walled specimen has to be taken into account, especially regarding environmental analyses (e.g., see discussion of paleo-water depth), the Paleocene assemblage includes vulnerable taxa in high numbers (e.g., Bulimina virginiana, Anomalinoides compressus; Fig. 3). This indicates that, while thicker-walled specimens could be relatively overrepresented, the overall environmental interpretations are still trustworthy. The sediments of the New Jersey Vincentown Formation also show a pattern of winnowing, which has been attributed to sedimentation under the influence of storms and strong bottom currents, establishing a well ventilated sea floor environment (Drobnyk, 1965; Stassen et al., 2015).

The Pre-Onset Excursion (POE) Enigma

In the ACP, the POE has been described in detail only from the SDB record, but the δ13C records of CamDor and Wilson Lake also show a potentially POE-related minor isotope excursion in the latest Paleocene (Babila et al., 2022; Doubrawa et al., 2022). At SDB, the POE is characterized by a gradual shift to a finer-grained interval, indicating an environment in which fine-grained sediments could accumulate without being removed by bottom currents. Foraminiferal data indicate that the setting was middle to outer neritic (∼100 m paleodepth) allowing for a continuous (re)deposition of fine sand, diluted by more silty material. This shift could imply a decrease in sorting by less vigorous bottom currents, but more likely shows the emergence of a second input source (Rahman & Plater, 2014). This second transport mechanism of the finer grains could be related to increased discharges of the paleo-Potomac river system, similar to the observation made during the PETM (Stassen et al., 2015; Rush et al., 2021). The transported sediments potentially have a different provenance than the ones of the kaolinite-enriched Marlboro Clay, as evidenced by the very different, low-kaolinite clay suite (Doubrawa et al., 2022). This could be fine sediments transported from closer to the coastline or sediment packages covering the source sediments of the Marlboro Clay.

Starting within the POE, some foraminifera species begin to decrease in relative numbers or fully vanish from the record (Fig. 3), indicating a shifting environment. The grain-size distribution, among others represented by a low LN(f/c), suggests the increase of river influence in the shelf area bringing in larger amounts of fresh water and suspended sediments (Fig. 8). A reduction in bottom water currents and storm events reworking the sediment floor, paired with increased river input, could enable the settlement of less-well sorted sediments (Rahman & Plater, 2014). Detrended Correspondence Analysis loadings indicate similar oxygenation levels as below the POE, but with a trend towards a more pulsed food input pointing towards an increased riverine influx. Pre-POE bottom water temperatures (based on Mg/Ca and δ18O proxies) centered around 16°C, gradually increasing towards the post-POE to around 18°C (Doubrawa et al., 2022), a possible influence on benthic foraminifera susceptible to warming vanishing from the environment.

The DCA sample scores around the POE are strongly influenced by the disappearance and reappearance of Bulimina virginiana (Fig. 3). At the onset of the POE, this buliminid reached its lowest abundance throughout the studied interval, along with a simultaneous decrease in Anomalinoides compressus. Other taxa from association 1a do not show a concurrent decline, indicating that a sudden change to dys- or anoxic bottom waters or a decreased food input is unlikely. The POE has been linked to sea floor acidification, with the lowest pH value around 207.5 m core depth (Babila et al., 2022). Bulimina virginiana and A. compressus are small, thin-walled foraminifera which would be more susceptible to dissolution than larger, thicker-walled species (Nguyen et al., 2011). Cibicidoides spp., Pseudouvigerina spp., and Paralabamina lunata, all with thicker tests and larger in size, as well as non-calcareous agglutinated species show a higher resistance against dissolution (Alegret & Thomas, 2013; Nguyen & Speijer, 2014). Robinson & Spivey (2019), studying a larger size fraction (>125 µm), found increased numbers of the agglutinated foraminifera Gaudryina pyramidata in the sediments of the POE interval and above at SDB, suggesting that this taxon filled a short-term available niche in the benthic assemblage during the acidification event. At Wilson Lake a decrease in B. virginiana is also observed in an interval that may correlate with the POE, but the thin-walled tests of the foraminifera and the overall preservation issues of the uppermost Paleocene sediments hamper distinguishing primary environmental changes (such as a pH drop) from taphonomic post-depositional alteration. In addition, the POE has been linked to a higher sedimentation rate (Doubrawa et al., 2022); the diversity remains high and there are no indications of a distinct faunal turnover. A tipping point causing a diversity crisis was not reached, in contrast to the situation at the onset of the PETM.

In the post-POE interval, Epistominella minuta reaches its peak abundance. This species, among others, is regarded as an indicator of an episodic, high food supply. The high food supply makes it possible for this taxon to thrive under varying oxygen conditions, including lower levels of oxygenation (Gibson et al., 1993; D’haenens et al., 2012; Deprez et al., 2015). Bulimina virginiana also indicates high food-availability (Self-Trail et al., 2017). In accordance, the DCA plot shows a strong shift towards the pulsed-food input endmember in the latest Paleocene (Figs. 9, 11). High and episodic food supply is typical for environments situated close to river mouths, with shifts in the consistency of the food supply amounts closely coupled to the riverine input and to subsequently the hydrological cycle on land. Riverine input did not dominate the setting fully, as a (modest) change in salinity would also be likely due to the higher amounts of freshwater intake. At SDB, planktic foraminifera remain present and even increase in abundance (higher %P, as well as in absolute numbers; Fig. 2). Changes in the planktic foraminiferal assemblage in that interval are mainly attributed to a temperature rise (Robinson & Spivey, 2019). Additionally, no peculiar salinity related changes are inferred from nannofossil assemblages (Self-Trail et al., 2012) or ostracoda assemblages (Tian et al., 2021). Parallel to the change in food supply, oxic conditions decrease. Cibicidoides spp., indicative of oxic conditions, decrease in the assemblage, and Pulsiphonina prima is rare. Pulsiphonina prima is considered stress-tolerant to environmental conditions like dysoxia (Stassen et al., 2015; Robinson & Spivey, 2019). This appearance is more noticeable in the dataset provided by Robinson & Spivey (2019). Pulsiphonina prima is present below the PETM in the New Jersey sites Bass River and Wilson Lake (Stassen et al., 2015), indicating that the environmental changes of the PETM opened up a niche for this species to move in and become dominant.

Association 1b, solely consisting of Paralabamina lunata, makes up to one third of the assemblage in the post-POE interval. This species is well-adapted to a moderately to well-ventilated shelf environment, with a higher, stable organic matter flux (Clemmensen & Thomsen, 2005; Deprez et al., 2015; Stassen et al., 2015). They are reported from deep-sea environments in association with changing food sources (Alegret & Thomas, 2013). The epibenthic P. lunata is common in high-oxygen environments. Still this taxon is recorded above the dissolution zone, after the onset of the PETM. Possibly, its adaptability to shifts in the food input could have provided P. lunata with the ability to withstand the changing conditions longer than other oxygen preferring species (Fig. 10; Clemmensen & Thomsen, 2005; Alegret & Thomas, 2013; Stassen et al., 2015).

Between the upper boundary of the POE at 205.9 m and the base of the PETM at 204 m, fine sand gradually becomes less abundant, and sediments become a slightly better sorted silty sand. In the aftermath of the POE, sediments indicate increased renewed winnowing by bottom currents and/or a reduced input of fine-grained sediments. In the transitional interval of the PETM (∼204.5–203 m), coarser material is nearly absent, which can be caused by either a decline or termination of sand input or a significant increase of finer-grained sediments, strongly diluting the sandy input. Latest Paleocene change in water depth can also cause a similar shift in grain-size distributions, with the gradual increase of fine silt, in comparison with sand, potentially relating to deepening. Additionally the increase of clay in comparison with the medium to coarser silt fraction could be caused by intensified runoff of the paleo-Potomac transporting additional fine sediments into the shelf (Fig. 8; Olsson & Wise, 1987; Immenhauser, 2009; Kopp et al., 2009), indicating (similar to the benthic foraminifera) an increased riverine input.

The POE marks the start of regional paleoenvironmental changes. It is lithologically distinctive from underlying sediments, indicating increasing riverine influences prior to the PETM. Within the POE, the overall temperature range of the bottom waters (assuming a stable regional δ18O seawater composition) starts to shift towards warmer temperatures by ∼+2°C already before the intense warming linked to the PETM (Fig. 11). The Mg/Ca-based paleotemperature data of the post-POE are similar to the pre-POE results, but data from the POE interval, and thus comparable temperatures, are missing. Planktic foraminiferal data show a tendency towards slightly higher temperatures around the POE (+∼2°C). In the post-POE interval, the planktic data indicate a return to pre-POE temperatures, before exhibiting a sharp rise (+∼5°C) above the dissolution zone (Babila et al., 2022). A gradual pre-PETM temperature rise of up to 4°C based on the organic paleothermometer TEX86 has also been reported from northern sites of the shelf (Bass River and Wilson Lake; Sluijs et al., 2007b). No POE has so far been detected at Bass River or Wilson Lake, which could be related to this pre-onset warming.

PETM Peak Warming Phase

The Marlboro Clay is a poorly sorted fine-silty clay unit (Fig. 8). The accumulation of fine-grained sediments and an increased number of well-preserved, more fragile foraminifera tests indicate a less abrasive, low-energy environment. The increased LN(f/c) values suggest a general lack of winnowing or reworking, probably due to strongly reduced or lack of bottom water currents (Rahman & Plater, 2014). Throughout the PETM core phase, the grain-size distribution remains stable, with a broad grain-size spectrum, and a high clay content.

Benthic foraminifera from association 1a, which make up most of the epibenthic species (Figs. 2, 3), either completely vanish before the PETM or persist in low numbers during the peak warming of the PETM CIE core phase. They are best adapted to well-ventilated bottom waters with a constant food flux. During the core phase, the foraminiferal assemblage diversity is severely reduced and dominated by four taxa: Bulimina virginiana (association 2b), Pulsiphonina prima, Anomalinoides acutus, and, to a lesser extent, Pseudouvigerina wilcoxensis (all association 3b; Fig. 3, Table 1). Pseudouvigerina spp. (association 3b) have their highest occurrence in SDB, Wilson Lake, and Bass River further up in the core phase, indicating that the initial environmental conditions of the PETM core phase, especially in the shallower sites, were not optimal for this taxon. The species of association 3a are known to be stress-tolerant, opportunistic taxa that can thrive in dynamic environments with higher temperatures, lowered salinity or low-oxygen conditions (Fig. 11; Gibson et al., 1993; Kaiho, 1994; Speijer et al., 1996; Gibson, 2001; Alegret et al., 2003; Deprez et al., 2015). They are part of the typical Midway-shelf fauna assemblage (Berggren & Aubert, 1975) and sometimes associated with river outflow (Stassen et al., 2015; Self-Trail et al., 2017). This assemblage, together with the disappearance of association 1 from the shelf, point to the establishment of adverse conditions. Long-lasting dysoxia could have been caused by salinity-induced stratification of the water column in a river-dominated environment in a time where storm-influenced mixing was low, as evidenced by the grain-size record. Site SDB was under the influence of quickly rising temperatures (Doubrawa et al., 2022) as well as an increased hydrological cycle, as modelled and observed from New Jersey sites (John et al., 2008; Rush et al., 2021). This caused an intensified transport of kaolinitic clays and food into the shelf, settling under low-energy conditions. The abundance of P. prima, A. acutus, P. wilcoxensis, but also B. virginiana suggests high food levels (Gibson et al., 1993; Gibson, 2001; Stassen et al., 2012c; Stassen et al., 2015). The presence of P. wilcoxensis, Spiroplectinella laevis, and Valvalabamina depressa additionally point to a more pulsed food source during the peak warming phase (Gibson et al., 1993; Self-Trail et al., 2017). The DCA (Fig. 9) shows the shift to the most dysoxic conditions of the interval, although long-term anoxic conditions were probably never reached. In comparison to the oxygen development, the change to a more pulsed food source seems to be delayed, a phenomenon also described from the New Jersey sites (Stassen et al., 2015).

This distinct shift in the benthic foraminiferal assemblage is typical for the PETM on the ACP, reacting to the extensive impact the PETM had on the shallow marine environment (Gibson, 2001; Stassen et al., 2015; Robinson & Spivey, 2019). For example, the Mattawoman Creek assemblage is dominated by B. virginiana (Robinson & Spivey, 2019), due to its close proximity to the river mouth, where it received the highest input of organic matter of all the sites. Bulimina virginiana percentages are strongly reduced in the more distal sites of Bass River and Wilson Lake, where Tappanina selmensis appears; this species is rare in the Maryland sites. Tappanina selmensis, usually a common outer-shelf member of the Midway-type fauna (e.g., Stassen et al., 2015), appears at SDB only in low numbers in recovery phase 2. It is commonly reported from environments providing a constant, high food supply (Kaiho, 1994; Alegret et al., 2003; Clemmensen & Thomsen, 2005). During the core phase at Bass River and Wilson Lake, T. selmensis is part of the dominant, opportunistic fauna. It was thus a main component of the fauna in the distal areas, and possibly reflects an upslope expansion of this taxon. Low oxygen levels and elevated levels of (degraded) organic matter were potentially sustained by the food-input of the fluvial discharge into this area (Stassen et al., 2015). All faunal parameters indicate a long-lasting shift to relatively continuous eutrophication with likely seasonal shifts on the shelf during the peak warming phase. These appear to be due to an evolving, more pulsed, maybe seasonal, flux in food. This is in accordance with the paleo-environmental evolution as observed in the more northern sites (Stassen et al., 2015).

PETM Recovery

At SDB in recovery phase 1, the LN(f/c) (Fig. 8) starts to decrease slightly, possibly indicating a renewed intensification of currents and winnowing. Association 2 becomes dominant and mostly consists of Bulimina virginiana, and to a lesser degree, by Valvalabamina depressa. Additionally, at the transition from core to recovery phase Paralabamina lunata (association 1b) re-appears. Both B. virginiana and P. lunata suggest a high food flux, with the latter indicating a more stable food input and a return to better ventilated bottom waters with increasing oxygen levels (Clemmensen & Thomsen, 2005; Alegret & Thomas, 2013; Deprez et al., 2015).

In Bass River, Pulsiphonina prima and P. lunata are also the most dominant taxa within recovery phase 1, with Paleocene taxa only returning as a minor part of the assemblage. This indicates a potential offset in the faunal recovery in deeper waters, with a stronger oxygen minimum zone influence. In the uppermost part of PETM CIE recovery 1 at SDB and throughout PETM CIE recovery 2, the typical PETM-taxa nearly vanish from the assemblage, giving way to Bulimina spp. or Dentalina species. In a later stage, Cibicidoides howelli and C. alleni return into the assemblage, suggesting further improvement of oxygenation and a constant food flux to the sea floor. Note that the acme of Bulimina callahani, as observed at Bass River (Stassen et al., 2015), is not recorded at SDB, suggesting at differentiation of environmental conditions between the more proximal and distal locations during the final recovery phase of the PETM.

In recovery phase 2, the LN(f/c) decreases further. The grain size distribution shifts back to increasingly silty sediments, with more bimodal grain size curves, likely related to a decrease in river input and/or increased winnowing. This more silty interval is also recorded at other sites in New Jersey (Ancora, Bass River) and linked to a renewed sorting of detrital input by intensified bottom currents, reflecting the end of river-dominated shelf deposition (Stassen et al., 2012c, 2015). Due to the unconformity truncating recovery phase 2, part of the lower Eocene is not preserved at SDB. The grain-size distribution of the overlying sediments does not fully shift back to a unimodal distribution, indicating the overall return to either a storm-dominated system (but less prominent as the pre-POE Paleocene conditions) or a deeper water setting with coarser-grained components composed of (authigenic) large glauconite grains.

To summarize, we can trace a slow, but steady faunal recovery after the environmental perturbations of the PETM CIE core phase, with many of the Paleocene benthic foraminifera reappearing on the shallow shelf.

Development of the Paleodepth on the Shelf

At SDB, the estimated paleodepth centers around 100 m. This estimate is shallower than depths suggested by Robinson & Spivey (2019), who calculate ∼125 m for the Paleocene and ∼145 m for the PETM core phase. This could be partially due to the use of a different size fraction for the benthic foraminiferal studies (>63-µm fraction vs. the >125-µm fraction by Robinson & Spivey, 2019), but mostly the use of diverging paleodepth ranges (Fig. 10; Stassen et al., 2015). The association-based calculations suggest a very stable sea-level throughout the latest Paleocene, while the taxa-based calculations indicate a decrease of up to 20 m towards the POE. This change can be attributed to the major decrease of Bulimina virginiana in that interval (Fig. 3), and the resulting change of relative numbers in the assemblage. As a stable late Paleocene sea-level has also been proposed in other studies (Stassen et al., 2015; Robinson & Spivey, 2019), we assume that the sea-level change during the POE may be an artefact of taphonomic alteration and/or increased acidification (Stassen et al., 2015; Makarova et al., 2017; Robinson & Spivey, 2019; Babila et al., 2022), impacting thin-walled species like B. virginiana or Anomalinoides compressus more than thicker-walled species (Nguyen et al., 2009; Doubrawa et al., 2022).

The taxa- and association-based estimates across the P-E boundary suggest a minor sea-level rise during the initial phases of the PETM. Results excluding association 3 show a sea-level rise of ∼10 m above the dissolution zone, in line but smaller than other findings at this site (∼25 m; Robinson & Spivey, 2019). The taxa-based estimation indicates a minor increase in water depth during the PETM peak warming phase, but additionally shows a further increase in the recovery phase. This apparent increase is attributed to the re-appearance of Paralabamina lunata in the assemblage, which was probably more influenced by a decrease in river influence and a return to a more constant food flux than to additional sea-level rise.

For the nearby site Mattawoman Creek, Robinson & Spivey (2019) report a reduction of water depth of up to 30 m. The relative sea-level decrease is attributed to the close proximity of this river delta site to the paleo-Potomac, and to high sediment-input rates during the PETM, which resulted in delta progradation even though sea-level increased. While being situated further away, the paleo-Potomac still had a significant influence on the sediments of SDB, as evidenced by the thick Marlboro Clay. An additional complication for paleodepth estimates at SDB is that it was too shallow for outer-shelf fauna to move in and thrive before and during the PETM. Typical taxa used to calculate water depth, like the deeper-dwelling Gavelinella beccariiformis, are absent in the samples; likewise, taxa indicating an extremely shallow environment are also absent. Most taxa identified cover a broader water depth spectrum. Nevertheless, a rising sea level at the onset of the PETM at SDB is in agreement with findings from the northern New Jersey sites where variations of 15–25 m are reported from Wilson Lake, Bass River, and Millville (Harris et al., 2010; Stassen et al., 2015; Makarova et al., 2017).

The benthic foraminifera and sediments of the South Dover Bridge core record environmental changes on the shelf. During the late Paleocene, SDB was situated on a well-ventilated shelf (∼100 m). A constant moderate to high food supply was available, resulting in a diverse benthic foraminiferal assemblage. With the pre-onset excursion (POE), benthic foraminiferal diversity started to decline. Bottom currents decreased, paired with a potential increase of river influence and a drop in pH.

Opportunistic taxa, commonly connected with the PETM, appeared first during or slightly after the POE, but in low numbers. After the POE, the environment started to shift back to pre-POE conditions, and bottom water currents increased slightly. Influx of fine-grained sediments started before the CIE onset, indicating an increase in regional river influence. Stress-tolerant taxa became a minor part of the benthic foraminiferal assemblage, and taxa preferring well-oxygenated waters began to disappear. The food source slowly shifted to a pulsed input mechanism.

With the PETM, extreme changes in the environment are recorded. The diversity of the benthic assemblage was strongly reduced, dominated by four species, with all other taxa either disappearing or only occurring in low numbers. Bottom currents diminished on a regional scale, and the sediment supply became more river-dominated; increased freshwater input occurred via the paleo-Potomac. This resulted in salinity-induced stratification of the water column with dys- to anoxic conditions at the sea floor. The food input became increasingly episodic but remained high. The low-energy environment enabled the deposition of the kaolinitic-rich Marlboro Clay. With the transition to the recovery phase, a shift to more pre-PETM conditions began, less pronounced in recovery phase 1 and more distinct in recovery phase 2. The river influence started to decline, while bottom currents took up again. The diversity of the benthic foraminiferal assemblage increased with rising oxygen levels and a more stable food source.

The calculated paleo-water depth of site SDB centered around 100 m, indicative of a middle neritic setting. Sea level rose ∼10 m during the PETM, but typical deeper-dwelling or very shallow-living taxa were not part of the assemblage, resulting in a seemingly more stable water depth than reported from other sites from the Atlantic Coastal Plain.

Family ALABAMINIDAE

Genus Alabamina Toulmin, 1941

Alabamina midwayensis (Brotzen, 1948)

Figs. 4.9a–c, A3.1

  • Alabamina midwayensis Brotzen, 1948, p. 99, pl. 16. figs. 12.

  • Alabamina midwayensis Brotzen in Olsson, 1960, p. 39, pl. 6, figs. 21–22.

  • Alabamina midwayensis Brotzen in Berggren, 1974, p. 431, pl. 5, figs. 15–16.

  • Alabamina midwayensis Brotzen in Charletta, 1980, p. 54, pl. 1, figs. 810.

  • Alabamina midwayensis Brotzen in Saint-Marc, 1992, p. 482, pl. 2, figs. 1112.

  • Alabamina midwayensis Brotzen in Stassen et al., 2015, pl. 2, figs. 18a–c.

Alabamina wilcoxensis (Toulmin, 1941)
Figs. 4.8a–c, A1.15a–b, A4.5

    Alabamina wilcoxensis (Toulmin, 1941)
    Figs. 4.8a–c, A1.15a–b, A4.5
  • Alabamina wilcoxensis Toulmin, 1941, p. 602, pl. 81, figs. 1014.

  • Alabamina wilcoxensis Toulmin, in Shifflett, 1948, p. 69, pl. 4, figs. 10a–b.

  • Alabamina wilcoxensis Toulmin, in Seaton, 1981, p. 54, pl. 4, figs. 13.

  • Alabamina wilcoxensis Toulmin, in Stassen et al., 2015, pl. 3, figs. 8a–c.

  • Alabamina wilcoxensis Toulmin, in Robinson & Spivey, 2019, p. 728, figs. A2r–t.

Family GAVELINELLIDAE

Genus Anomalinoides Brotzen, 1942
Anomalinoides acutus (Plummer, 1927)
Figs. 4.1a–c, A1.7a–b, A4.6

    Genus Anomalinoides Brotzen, 1942
    Anomalinoides acutus (Plummer, 1927)
    Figs. 4.1a–c, A1.7a–b, A4.6
  • Anomalina ammonoides (Reuss) var. acuta Plummer, 1927, p. 149, pl. 10, fig. 2a–c.

  • Anomalina acuta Plummer, in Toulmin, 1941, p. 608, pl. 82, figs. 910.

  • Anomalinoides acuta (Plummer), in Olsson, 1960, p. 51, pl. 11, figs. 45 

  • Anomalinoides acuta (Plummer), in Kellough, 1965, p. 116, pl. 15, fig. 6.

  • Anomalinoides acuta (Plummer), in Berggren & Aubert, (1975) p. 149, pl. 5, figs. 4a–d, pl. 8, figs. 3a–b, pl. 9, fig. 1, pl. 12, fig. 5, pl. 18, fig. 2, pl. 19, fig. 2.

  • Anomalinoides acuta (Plummer) in Charletta, 1980, p. 64, pl. 4, figs. 16–18.

  • Anomalinoides acutus (Plummer), in Stassen et al., 2015, pl. 2, figs. 19a–c.

Anomalinoides affinis (Hantken, 1875)
Figs. 4.2a–c, A1.9a–b

    Anomalinoides affinis (Hantken, 1875)
    Figs. 4.2a–c, A1.9a–b
  • Pulvinulina affinis Hantken, 1875, p. 78, pl. 10, fig. 6.

  • Truncatulina welleri Plummer, 1926, p. 143, pl. 9, fig. 6.

  • Anomalinoides pseudowelleri Olsson, 1960, p. 52, pl. 12, figs. 13.

  • Anomalinoides affinis (Hantken), in Stassen et al., 2015, p. 11, pl. 1, figs. 1011.

  • Anomalinoides affinis (Hantken), in Self-Trail et al., 2017, p. 8, pl. 6, figs. 1314.

Note: We consider Truncatulina welleri (Plummer, 1926) and Anomalinoides pseudowelleri (Olsson, 1960) as junior synonyms of Anomalinoides affinis.

Anomalinoides compressus (Olsson, 1960)
Figs. 4.4a–c, A1.10a–b, A3.2

    Anomalinoides compressus (Olsson, 1960)
    Figs. 4.4a–c, A1.10a–b, A3.2
  • Cibicides compressa Olsson, 1960, p. 53, pl. 12, figs. 1315.

  • Cibicides compressus Olsson, in Nogan, 1964, p. 46, pl. 7, figs. 46.

  • Anomalinoides alazaensis (Nuttal), in D’haenens et al., 2012, pl. 1, figs. 18a–c.

Anomalinoides umboniferus (involute) (Schwager, 1883)
Fig. 4.3a–b, A1.8a–b

    Anomalinoides umboniferus (involute) (Schwager, 1883)
    Fig. 4.3a–b, A1.8a–b
  • Discorbis umbonifera Schwager, 1883, p. 126, pl. (17) 5, fig. 14a–c.

  • Anomalinoides umboniferus (Schwager), in Nogan, 1964, p. 42, plate 6, 16–21.

Family SPIROPLECTAMMINIDAE

Genus Bolivinopsis Yakovlev, 1891
Bolivinopsis emmendorferi (Jennings, 1936)
Figs. 7.27a–b, A2.24, A3.12

    Genus Bolivinopsis Yakovlev, 1891
    Bolivinopsis emmendorferi (Jennings, 1936)
    Figs. 7.27a–b, A2.24, A3.12
  • Spiroplectoides emmendorferi Jennings, 1936, pl. 3, fig. 8.

  • Spiroplectammina mexiaensis Lalicker, in Cushman 1951, p. 6, pl. 1, figs. 25–26.

  • Bolivinopsis emmendorferi (Jennings), in Olsson, 1960, p. 27, pl. 4, fig. 7.

Family BULIMINIDAE

Genus Bulimina d’Orbigny, 1826
Bulimina cacumenata Cushman & Parker, 1936
Figs. 7.7, 7.9a–b, A2.17

    Genus Bulimina d’Orbigny, 1826
    Bulimina cacumenata Cushman & Parker, 1936
    Figs. 7.7, 7.9a–b, A2.17
  • Bulimina cacumenata Cushman & Parker, 1936 p. 40, pl. 7, fig. 3.

  • Bulimina whitei Martin in Charletta, 1980, p. 61, pl. 3, figs. 46.

  • Bulimina cacumenata Cushman & Parker, in Seaton, 1981, p. 42, pl. 2, fig. 4.

  • Bulimina cacumenata Cushman & Parker, in Stassen et al., 2015, pl. 3, fig. 5.

Bulimina hornerstownensis Olsson, 1960
Figs. 7.6a–b, A2.15, A3.8

    Bulimina hornerstownensis Olsson, 1960
    Figs. 7.6a–b, A2.15, A3.8
  • Bulimina hornerstownensis Olsson, 1960, p. 32, pl. 5, figs. 67.

  • Bulimina sp. 3 in Charletta, 1980, p. 62, pl. 4, figs. 34.

  • Bulimina hornerstownensis Olsson, in Stassen et al., 2015, pl. 1, fig. 5.

Bulimina ovata d’Orbigny, 1846
Figs. 7.8a–b, A2.14

    Bulimina ovata d’Orbigny, 1846
    Figs. 7.8a–b, A2.14
  • Bulimina ovata d’Orbigny, 1846, p. 185, pl. 11, figs. 1314.

  • Bulimina virginiana Cushman, in Nogan, 1964, p. 32, pl. 2, fig. 19.

  • Bulimina ovata d’Orbigny, in Seaton, 1981, p. 42, pl. 2, fig. 9.

  • Bulimina ovata d’Orbigny, in Stassen et al., 2015, p. 8, pl. 2, fig. 3.

Bulimina virginiana (Cushman, 1944)
Figs. 7.5a–b, A2.16, A3.16

    Bulimina virginiana (Cushman, 1944)
    Figs. 7.5a–b, A2.16, A3.16
  • Angulogerina virginiana Cushman, 1944, p. 25, pl. 4, fig. 23.

  • Angulogerina virginiana Cushman, in Shifflett, 1948, p. 64, pl. 3, fig. 17.

  • Bulimina pseudocacumenata Olsson, 1960, p. 33, pl. 5, fig. 5.

  • Bulimina virginiana (Cushman), in Nogan, 1964, p. 32, pl. 2, fig. 20.

  • Pyramidina virginiana Cushman, in Poag (in Mixon), 1989, pl. 1, figs. 30–32.

  • Bulimina virginiana (Cushman), in Stassen et al., 2015, p. 5, pl. 1, fig. 4.

  • Bulimina virginiana (Cushman), in Arreguin-Rodriguez et al., 2018, p. 17, pl. 5, fig. 7.

Genus Buliminella Cushman, 1911
Buliminella marylandica Nogan, 1964
Fig. 7.4 

    Genus Buliminella Cushman, 1911
    Buliminella marylandica Nogan, 1964
    Fig. 7.4 
  • Buliminella marylandica Nogan, 1964, p. 31, pl. 2, fig. 18.

  • Buliminella marylandica Nogan, in Revets, 1990, p. 341, pl. 4., figs. 79.

Family CIBICIDAE

Genus Cibicidoides Thalmann, 1939
Cibicidoides alleni (Plummer, 1926)
Figs. 5.6a–c, A1.1a–b, A3.3

    Genus Cibicidoides Thalmann, 1939
    Cibicidoides alleni (Plummer, 1926)
    Figs. 5.6a–c, A1.1a–b, A3.3
  • Truncatulina alleni Plummer, 1926, p. 144, pl. 10, fig. 4.

  • Cibicidoides alleni (Plummer), in Berggren, 1974, p. 430, pl. 5, figs. 15.

  • Cibicidoides aff. alleni (Plummer), in Charletta, 1980, p. 57, pl. 2, figs. 13.

  • Cibicidoides alleni (Plummer), in Stassen et al., 2015, p. 5, pl. 1, figs. 13a–c.

Cibicidoides howelli (Toulmin, 1941)
Figs. 5.10a–c, A1.2a–b, A3.4

    Cibicidoides howelli (Toulmin, 1941)
    Figs. 5.10a–c, A1.2a–b, A3.4
  • Cibicides howelli Toulmin, 1941, p. 609, pl. 82, figs. 16–18.

  • Cibicides howelli Toulmin, in Nogan, 1964, p. 46, pl. 7, figs. 79.

  • Hanzawaia mauricensis (Howe and Roberts), in Charletta, 1980, p. 60, pl. 3, figs. 810.

  • Cibicides howelli Toulmin, in Seaton, 1981, p. 44, pl. 10, figs. 13.

  • Cibicidoides eocaenus (Gümbel), in D’haenes et al., 2012, pl. 1, figs. 20a–b.

  • Cibicidoides howelli (Toulmin), in Stassen et al., 2015, p. 11, pl. 1, figs. 14a–c & 15a–c.

Cibicidoides irenae (van Bellen, 1946)
Cibicides irenae van Bellen, 1946, p. 82, pl. 12, figs. 19–21.

    Cibicidoides irenae (van Bellen, 1946)
    Cibicides irenae van Bellen, 1946, p. 82, pl. 12, figs. 19–21.
  • Cibicides irenae van Bellen, in Nogan, 1964, p. 46, pl. 7, figs. 1012.

  • Cibicides irenae van Bellen, in Seaton, 1981, p. 45, pl. 10, figs. 79.

Cibicidoides marylandicus (Shifflett, 1948)
Figs. 5.8a–c, A1.3a–b

    Cibicidoides marylandicus (Shifflett, 1948)
    Figs. 5.8a–c, A1.3a–b
  • Cibicides marylandicus Shifflett, 1948, p. 74, pl. 5, figs. 46.

  • Cibicides marylandicus Shifflett, 1960, p. 53, pl. 12, figs. 46.

  • Cibicides marylandicus Shifflett, in Nogan, 1964, p. 46, pl. 7, figs. 1315.

  • Cibicidoides marylandicus (Shifflett), in Poag (in Mixon), 1989, pl. 2, figs. 1012.

Cibicidoides neelyi (Jennings, 1936)
Figs. 5.9a–c, A14a–b

    Cibicidoides neelyi (Jennings, 1936)
    Figs. 5.9a–c, A14a–b
  • Cibicides neelyi Jennings, 1936, p. 39, pl. 5, figs. 4a–c.

  • Cibicides neelyi Jennings, in Shifflett, 1948, p. 75, pl. 5, figs. 78.

  • Cibicides neelyi Jennings, in Olsson, 1960, p. 53, pl. 12, figs. 46.

  • Cibicides neelyi Jennings, in Nogan, 1964, p. 47, pl. 7, figs. 16–18.

  • Anomalinoides neelyi (Jennings), in Poag (in Mixon), 1989, pl. 2, figs. 79.

Cibicidoides succedens (Brotzen, 1948)
Figs. 5.7a–c, A1.5a–b

    Cibicidoides succedens (Brotzen, 1948)
    Figs. 5.7a–c, A1.5a–b
  • Cibicides succedens Brotzen, 1948, p. 80, pl. 12, figs. 12.

  • Cibicides succedens Brotzen, in Olsson, 1960, p. 53, pl. 12, figs. 1012.

  • Cibicidoides succedens (Brotzen), in Saint-Marc, 1993, p. 482, pl. 2, fig. 6.

  • Cibicidoides succedens (Brotzen), in Speijer et al., 1996, p. 123, pl. 2, figs. 1a–c.

Family BOLIVINITIDAE

Genus Coryphostoma Loeblich & Tappan, 1962
Coryphostoma midwayensis (Cushman, 1936)
Figs. 7.25a–b, A2.23

    Genus Coryphostoma Loeblich & Tappan, 1962
    Coryphostoma midwayensis (Cushman, 1936)
    Figs. 7.25a–b, A2.23
  • Bolivina midwayensis Cushman, 1936, p. 50, pl. 7, figs. 12.

  • Bolivina midwayensis Cushman, in Poag, 2012, p. 117, pl. 14, figs. 21–22.

  • Coryphostoma midwayensis (Cushman), in Stassen et al., 2015, p. 13, pl. 2, fig. 13.

Family NODOSARIIDAE

Genus Dentalina Risso, 1826
Dentalina–Dentalinoides group ∼ Dentalinoides (cf.) longiscata (d’Orbigny)
Figs. 7.14, A3.10

    Genus Dentalina Risso, 1826
    Dentalina–Dentalinoides group ∼ Dentalinoides (cf.) longiscata (d’Orbigny)
    Figs. 7.14, A3.10
  • Nodosaria longiscata d’Orbigny, 1846, p. 32, pl. 1, figs. 1012.

  • Dentalina sp. 6 in Olsson, 1960, p. 17, pl. 3, figs. 6.

Note: Due to the very low number and often only fragmented preservation, we identified the Dentalina specimen only to genus level and grouped all species belonging to the genus Dentalina together.

Family ELLIPSOIDINIDAE

Genus Ellipsonodosaria Silvestri, 1900
Ellipsonodosaria midwayensis Cushman & Todd, 1946
Fig. 7.15 

    Genus Ellipsonodosaria Silvestri, 1900
    Ellipsonodosaria midwayensis Cushman & Todd, 1946
    Fig. 7.15 
  • Ellipsonodosaria midwayensis Cushman & Todd, 1946, p. 61, pl. 10, fig. 25.

  • Ellipsonodosaria midwayensis Cushman & Todd, in Cushman, 1951, p. 47, pl. 13, figs. 610.

  • Stilostomella midwayensis (Cushman & Todd), in Berggren & Aubert, 1975, pl. 9, fig. 8, pl. 10, fig. 5, pl. 19, fig. 3.

  • “Stilostomella” midwayensis (Cushman & Todd), in Poag, 2012, p. 148, pl. 22, figs. 36.

Family EOUVIGERINIDAE

Genus Eouvigerina Cushman, 1926
Eouvigerina whitei Brotzen, 1936
Figs. 7.29a–b, A2.26

    Genus Eouvigerina Cushman, 1926
    Eouvigerina whitei Brotzen, 1936
    Figs. 7.29a–b, A2.26
  • Eouvigerina whitei Brotzen, 1936, p. 124.

  • Eouvigerina whitei? Brotzen, in Stassen et al., 2015, p. 13, pl. 2, fig. 9.

Family PSEUDOPARRELLIDAE

Genus Epistominella Husezima & Maruhasi, 1944
Epistominella exigua (Brady, 1884) var. multiloculata Kaiho, 1984
Figs. 4.10a–c, A1.14a–b

    Genus Epistominella Husezima & Maruhasi, 1944
    Epistominella exigua (Brady, 1884) var. multiloculata Kaiho, 1984
    Figs. 4.10a–c, A1.14a–b
  • Epistominella exigua multiloculata Kaiho, 1984, p. 123, pl. 9, figs. 5a–c.

Epistominella minuta (Olsson, 1960)
Figs. 5.2a–c, A1.17a–b, A3.5

    Epistominella minuta (Olsson, 1960)
    Figs. 5.2a–c, A1.17a–b, A3.5
  • Pseudoparrella minuta Olsson, 1960, p. 40, pl. 6, figs. 79.

  • Epistominella minuta (Olsson), in Olsson, 1964, p. 36, pl. 3, fig. 78.

  • Epistominella minuta (Olsson), in Charletta, 1980, p. 54, p. 1, figs. 57.

  • Epistominella minuta (Olsson), in Poag (in Mixon), 1989, pl. 3, figs. 1315.

  • Pseudoparrella minuta Olsson, in D’haenenes et al., 2012, pl. 1, figs. 20a–b.

  • Epistominella minuta (Olsson), in Poag, 2012, p. 160, pl. 24, figs. 46.

  • Epistominella minuta (Olsson), in Deprez et al., 2015, pl. 1, figs. 12a–c.

Epistominella exigua var. multicamerata (Kaiho, 1984)
Figs. 4.10a–c, A1.14a–b, A3.14

    Epistominella exigua var. multicamerata (Kaiho, 1984)
    Figs. 4.10a–c, A1.14a–b, A3.14
  • Pulvinulina exigua var. obtusa Burrows and Holland, 1897, p. 49, pl. 2, fig. 25.

  • Pulvinulina exigua H. B. Brady var. obtusa Burrows and Holland, in Plummer, 1926, p. 151, pl. 11, figs. 2a–c.

  • Alabamina obtusa Burrows & Holland, in Aubert & Berggren, 1976, p. 429, pl. 8, fig. 4.

Family ELLIPSOLAGENIDAE

Genus Fissurina Reuss, 1850
Fissurina group
Figs. 6.8a–c, A2.10

Note: Due to the very low number and often only fragmented preservation, we identified the Fissurina specimen only to genus level and grouped all species belonging to the genus Fissurina together.

Family BOLIVINITIDAE

Genus Fursenkoina Loeblich & Tappan, 1961
Fursenkoina aquiensis Nogan, 1964
Figs. 7.26a–b, A2.18

    Genus Fursenkoina Loeblich & Tappan, 1961
    Fursenkoina aquiensis Nogan, 1964
    Figs. 7.26a–b, A2.18
  • Fursenkoina aquiensis Nogan, 1964, p. 33, pl. 2, fig. 28–29.

  • Fursenkoina aquiensis Nogan, in Stassen et al., 2015, p. 13, pl. 2, fig. 5.

Fursenkoina wilcoxensis (Cushman & Ponton, 1932)
Figs. 7.24a–b, A2.19, A4.8

    Fursenkoina wilcoxensis (Cushman & Ponton, 1932)
    Figs. 7.24a–b, A2.19, A4.8
  • Virgulina wilcoxensis Cushman & Ponton, 1932, p. 67, pl. 8, fig. 22.

  • Fursenkoina wilcoxensis (Cushman & Ponton), in Nogan, 1964, p. 33, pl. 2, fig. 27.

  • Fursenkoina wilcoxensis (Cushman & Ponton), 1981, pl. 2, figs. 78.

  • Fursenkoina wilcoxensis (Cushman & Ponton), in Stassen et al., 2015, p. 13, pl. 2, fig. 4.

Family VERNEUILINIDAE

Genus Gaudryina d’Orbigny, 1839
Gaudryina pyramidata (Cushman, 1926)
Fig. 7.31 

    Genus Gaudryina d’Orbigny, 1839
    Gaudryina pyramidata (Cushman, 1926)
    Fig. 7.31 
  • Gaudryina laevigata Franke var. pyramidata Cushman, 1926, p. 587, pl. 16, fig. 8.

  • Gaudryina pyramidata (Cushman), in Stassen et al., 2015, p. 15, pl. 3, figs. 23.

Family CASSIDULINIDAE

Genus Globocassidulina Voloshinova, 1960
Globocassidulina subglobosa (Brady, 1881)
Figs. 7.1a–b, A2.3a–b, A4.2

    Genus Globocassidulina Voloshinova, 1960
    Globocassidulina subglobosa (Brady, 1881)
    Figs. 7.1a–b, A2.3a–b, A4.2
  • Cassidulina subglobosa Brady, 1881, p. 60 not figured.

  • Globocassidulina subglobosa Brady, in D’haenens, 2012, pl. 2, figs. 45.

  • Globocassidulina subglobosa Brady, in Poag, 2012, p. 119, pl. 15, figs. 34.

Family POLYMORPHINIDAE

Genus Globulina d’Orbigny, 1839
Globulina (d’Orbigny, 1839) group
Fig. A2.9 

    Genus Globulina d’Orbigny, 1839
    Globulina (d’Orbigny, 1839) group
    Fig. A2.9 

Note: Due to the very low number and often only fragmented preservation, we identified the Globulina specimen only to genus level and grouped all species belonging to the genus Globulina together.

Genus Guttulina d’Orbigny, 1839
Guttulina (d’Orbigny) group
Figs. 6.9a–c 

    Genus Guttulina d’Orbigny, 1839
    Guttulina (d’Orbigny) group
    Figs. 6.9a–c 

Note: Due to the very low number and often only fragmented preservation, we identified the Guttulina specimen only to genus level and grouped all species belonging to the genus Guttulina together.

Genus Ramulina T.R. Jones in Wright, 1875
Ramulina pseudoaculeata (Olsson, 1960)
Figs. 7.12, A1.12

    Genus Ramulina T.R. Jones in Wright, 1875
    Ramulina pseudoaculeata (Olsson, 1960)
    Figs. 7.12, A1.12
  • Dentalina pseudoaculeata Olsson, 1960, p. 14, pl. 3, figs. 12.

  • Ramulina pseudoaculeata (Olssosdfgn), in Sliter, 1968, p. 79, pl. 10, fig. 8.

Family CANCRISIDAE

Genus Gyroidinoides Brotzen, 1942
Gyroidinoides aequilateralis (Plummer, 1927)
Figs. 4.6a–c, A1.11a–b, A4.1

    Genus Gyroidinoides Brotzen, 1942
    Gyroidinoides aequilateralis (Plummer, 1927)
    Figs. 4.6a–c, A1.11a–b, A4.1
  • Rotalia aequilateralis Plummer, 1927, p. 155, pl. 12, fig. 3.

  • Gyroidinoides peramplus (Cushman & Stainforth), in Charletta, 1980, pl.2, figs. 46.

  • Gyroidinoides aequilateralis (Plummer), in Poag (in Mixon), 2012, p. 182, pl. 29, figs. 1315.

  • Gyroidinoides aequilateralis (Plummer), in Stassen et al., 2015, pl. 3, figs. 910.

Gyroidinoides octocameratus (Cushman & Hanna, 1927)
Figs. 4.7a–c, A1.12a–b, A3.6

    Gyroidinoides octocameratus (Cushman & Hanna, 1927)
    Figs. 4.7a–c, A1.12a–b, A3.6
  • Gyroidina soldanii d’Orbigny, octocamerata Cushman & Hanna, 1927, p. 223, pl. 14, figs. 16–18.

  • Gyroidinoides octocameratus (Cushman & Hanna), in Nogan, 1964, p. 35, pl. 3, figs. 35.

  • Gyroidinoides octocameratus (Cushman & Hanna), in Charletta, 1980, p. 55, pl. 1, figs. 15–17.

  • Gyroidinoides octocameratus (Cushman & Hanna), in Seaton, 1981, p. 54, pl. 3, figs. 13.

Family LAGENIDAE

Genus Lagena Walker & Boys, 1798
Lagena group
Figs. 7.1011, A2.11

    Genus Lagena Walker & Boys, 1798
    Lagena group
    Figs. 7.1011, A2.11

Note: Due to the very low number and often only fragmented preservation, we identified the Lagena specimen only to genus level and grouped all species belonging to the genus Lagena together.

Family VAGINULINIDAE

Genus Lenticulina Lamarck, 1804
Lenticulina group
Figs. 6.7a–c, A3.7

Note: The preservation of the specimen is rather poor, causing most specimens to be broken and low in numbers. To prevent misidentification, species belonging to the genus Lenticulina were grouped together.

Order MILIOLIDA

Miliolida group

Note: Miliolida a very sparse in the assemblage, to prevent misidentification of taxa belonging to the order Miliolida were grouped together.

Family DISCORBIDAE

Genus Neoeponides Reiss, 1960
Neoeponides lotus (Schwager, 1883)
Figs. 5.4a–c, A2.2a–b

    Genus Neoeponides Reiss, 1960
    Neoeponides lotus (Schwager, 1883)
    Figs. 5.4a–c, A2.2a–b
  • Pulvinulina lotus Schwager, 1883, p. 132, pl. 28, fig. 9.

  • Eponides lotus (Schwager), in Seaton, 1981, p. 44, pl. 3, figs. 79.

  • Neoeponides lotus (Schwager) in Stassen et al., 2015, p. 15, pl. 3, figs. 15a–c.

Family NODOSARIIDAE

Genus Nodosaria Lamarck, 1816
Nodosaria group
Fig. 7.13 

    Genus Nodosaria Lamarck, 1816
    Nodosaria group
    Fig. 7.13 

Note: The preservation of the specimen is rather poor, causing most specimen to be broken and low in numbers. To prevent misidentification species belonging to the genus Nodosaria were grouped together.

Family NONIONIDAE

Genus Nonion Montfort, 1808
Nonion group

    Genus Nonion Montfort, 1808
    Nonion group

Note: All Nonion species are grouped due to low occurrences.

Genus Nonionella Cushman, 1926
Nonionella group
Figs. 6.6a–c, A1.6a–b

    Genus Nonionella Cushman, 1926
    Nonionella group
    Figs. 6.6a–c, A1.6a–b

Note: All Nonionella species are grouped due to low occurences.

Family ALABAMINIDAE

Genus Osangularia Brotzen, 1940
Osangularia plummerae Brotzen, 1940
Figs. 5.5a–c, A1.6a–b

    Genus Osangularia Brotzen, 1940
    Osangularia plummerae Brotzen, 1940
    Figs. 5.5a–c, A1.6a–b
  • Osangularia plummerae Brotzen, 1940, p. 30, pl. 10, fig. 1 and pl. 15, fig. 2.

  • Parrella convexa Olsson, 1960, p. 38, pl. 6, figs. 1315.

  • Osangularia plummerae Brotzen, in Berggren and Aubert, 1975, p. 147, pl. 3, figs. 6a–g, pl. 9, fig. 2, pl. 10, fig. 4, pl. 13, fig. 11, pl. 14, fig. 10, pl. 17, fig. 6, pl. 18, fig. 3.

  • Osangularia plummerae Brotzen, in Deprez et al., 2015, p. 64, pl. 2, figs. 15a–c.

  • Osangularia plummerae Brotzen, in Stassen et al., 2015, p. 11, pl. 1, figs. 12a–c.

Family GAVELINELLIDAE

Genus Paralabamina Hansen 1970
Paralabamina lunata (Brotzen, 1948)
Figs. 5.1a–c, A1.18a–b, A3.13

    Genus Paralabamina Hansen 1970
    Paralabamina lunata (Brotzen, 1948)
    Figs. 5.1a–c, A1.18a–b, A3.13
  • Eponides lunata Brotzen, 1948, p. 77, pl. 10, figs. 17–18.

  • Eponides lunata Brotzen, in Olsson, 1960.

  • Paralabamina lunata (Brotzen), in Deprez et al., 2015, p. 64, pl. 2, figs. 12a–c.

  • Paralabamina lunata (Brotzen), in Stassen et al., 2015, p. 11, pl. 1, figs. 8a–c.

Family TURRILINIDAE

Genus Pseudouvigerina Cushman, 1927

    Genus Pseudouvigerina Cushman, 1927

Note: Some specimens have markers from both P. triangularis and P. wilcoxensis. We noted those specimens under P. triangularis/wilcoxensis intermediate, to clearly distinguish them from specimen which clearly fall under one of the two species descriptions.

Pseudouvigerina triangularis Jennings, 1936
Figs. 7.17–19, A2.20, A3.11

    Pseudouvigerina triangularis Jennings, 1936
    Figs. 7.17–19, A2.20, A3.11
  • Pseudouvigerina triangularis Jennings, 1942, p. 29, pl. 3, fig. 16.

  • Pseudouvigerina triangularis Jennings, in Olsson, 1960, p. 30, pl. 4, fig. 22.

  • Angulogerina cuneate, in Harris et al., 2010, p. 4.

  • Pseudouvigerina triangularis Jennings, in Stassen et al., 2015, p. 15, pl. 3, fig. 4.

Pseudouvigerina wilcoxensis Cushman & Ponton, 1932
Figs. 7.20–21, A4.9

    Pseudouvigerina wilcoxensis Cushman & Ponton, 1932
    Figs. 7.20–21, A4.9
  • ?not Uvigerina seligi Cushman, 1925, p.1, pl. 4, fig. 1.

  • Pseudouvigerina seligi (Cushman), in Olsson, 1960, p. 30, pl. 4, fig. 23.

  • Pseudouvigerina wilcoxensis Cushman & Ponton, in Olsson, 1960, p. 34, pl. 5, fig. 12.

  • Trifarina wilcoxensis (Cushman & Ponton), in Charletta, 1980, p. 62, pl. 4, fig. 5.

  • Pseudouvigerina wilcoxensis Cushman & Ponton, in Stassen et al. 2015, p.13, pl. 2, fig. 6.

Family NONIONIDAE

Genus Pullenia Parker & Jones, 1862
Pullenia group ∼ Pullenia quinqueloba (Reuss, 1851)
Figs. 6.10a–b, A2.8

    Genus Pullenia Parker & Jones, 1862
    Pullenia group ∼ Pullenia quinqueloba (Reuss, 1851)
    Figs. 6.10a–b, A2.8
  • Nonionina quinqueloba Reuss, 1851, p. 71, pl. 5, fig. 31.

  • Pullenia quinqueloba (Reuss), in Stassen et al., 2015, p. 11, pl. 1, figs. 7a–c.

Note: All Pullenia species are grouped due to low occurrences and Pullenia quinqueloba is the most common form.

Family SIPHONIDAE

Genus Pulsiphonina Brotzen, 1948
Pulsiphonina prima (Plummer, 1926)
Figs. 6.5a–c, A2.4a–b, A4.7

    Genus Pulsiphonina Brotzen, 1948
    Pulsiphonina prima (Plummer, 1926)
    Figs. 6.5a–c, A2.4a–b, A4.7
  • Siphonina prima Plummer, 1926, p. 148, pl. 12, fig. 4.

  • Pulsiphonina prima (Plummer), in Olsson, 1960, p. 38, pl. 7, figs. 13.

  • Pulsiphonina prima (Plummer), in Berggren & Aubert, 1975, p. 156, pl. 3, fig. 5.

  • Pulsiphonina prima (Plummer), in Stassen et al., 2015, p. 13, pl. 2, figs. 17a–c.

Family GLABRATELLIDAE

Genus Rosalina d’Orbigny, 1826
Rosalina group

    Genus Rosalina d’Orbigny, 1826
    Rosalina group

Note: All Rosalina species are grouped due to low occurrences.

Rosalina crenulata Hofker, 1962
Figs. 6.4a–c, A2.1a–b

    Rosalina crenulata Hofker, 1962
    Figs. 6.4a–c, A2.1a–b
  • Rosalina crenulata Hofker, 1962, p. 11, fig. 5.

Rosalina millettii (Wright, 1911)
Figs. 6.3a–c, A2.7a–b

Family SPIROPLECTAMMINIDAE

Genus Spiroplectammina Cushman, 1927
Spiroplectammina wilcoxensis Cushman & Ponton, 1932
Figs. 7.33, A2.25

    Genus Spiroplectammina Cushman, 1927
    Spiroplectammina wilcoxensis Cushman & Ponton, 1932
    Figs. 7.33, A2.25
  • Spiroplectammina wilcoxensis Cushman & Ponton, 1932, p. 78, pl. 13, figs. 12.

  • Spiroplectammina wilcoxensis Cushman & Ponton, in Nogan, 1964, p. 21, pl. 1, fig. 4.

Family SPIROPLECTAMMINIDAE

Genus Spiroplectinella Kisel’man, 1972
Spiroplectinella laevis (Roemer, 1841)
Figs. 7.28a–b, A2.27, A4.3

    Genus Spiroplectinella Kisel’man, 1972
    Spiroplectinella laevis (Roemer, 1841)
    Figs. 7.28a–b, A2.27, A4.3
  • Textularia laevis Roemer, 1841, p. 97, pl. 15, fig. 17.

  • Spiroplectamina mississippiensis (Cushman) in Charletta, 1980, p. 54, pl. 1, fig. 11.

  • Spiroplectammina plummerae, in Harris et al., 2010.

  • Spiroplectinella laevis (Roemer), in Stassen et al., 2015, p. 13, pl. 2, fig. 1.

Family BOLIVINIDAE

Genus Tappanina Montanaro Gallitelli, 1955
Tappanina selmensis (Cushman, 1933)
Figs. 7.3a–b, A2.13, A3.17

    Genus Tappanina Montanaro Gallitelli, 1955
    Tappanina selmensis (Cushman, 1933)
    Figs. 7.3a–b, A2.13, A3.17
  • Bolivinita selmensis Cushman, 1933, p. 58, pl. 7, figs. 34.

  • Eouvigerina americana Cushman, 1936, p. 123, pl. 9, figs. 4a–c.

  • Tappanina selmensis (Cushman), in Olsson, 1960, p. 30.

  • Tappanina selmensis (Cushman), in Nogan, 1964, p. 30, pl. 2, fig. 13.

  • Tappanina selmensis (Cushman), in Stassen et al., 2015, p. 13, pl. 2, fig. 10.

Family TROCHAMMINIDAE

Genus Trochammina Parker & Jones, 1859
Trochammina group
Figs. 7.30a–b, 1A.28

    Genus Trochammina Parker & Jones, 1859
    Trochammina group
    Figs. 7.30a–b, 1A.28

Note: All Trochammina species are grouped due to low occurrences.

Family TURRILINIDAE

Genus Turrilina Andreae, 1884
Turrilina brevispira Ten Dam, 1944
Figs. 7.2a–b, A3.9

    Genus Turrilina Andreae, 1884
    Turrilina brevispira Ten Dam, 1944
    Figs. 7.2a–b, A3.9
  • Bulimina robertsi Howe & Ellis, 1939, p. 63, pl. 8, figs. 32–33.

  • Turrilina brevispira Ten Dam, 1944, p. 110, pl. 3, fig. 14.

  • Turritilina sp., in Charletta, 1980, p. 62, pl. 4, figs. 12.

  • Turrilina brevispira Ten Dam, in D’haenens et al., 2012, p. 20, pl. 2, fig. 17.

  • Turrilina brevispira Ten Dam, in Stassen et al., 2015, p. 15, pl. 3, fig. 7.

Family UVIGERINIDAE

Genus Uvigerina d’Orbigny, 1826
Uvigerina elongata Cole, 1927
Figs. 7.23, A2.22

    Genus Uvigerina d’Orbigny, 1826
    Uvigerina elongata Cole, 1927
    Figs. 7.23, A2.22
  • Uvigerina elongata Cole, 1927, p. 26, pl. 4, figs. 23.

  • Uvigerina elongata Cole, in Charletta, 1980, p. 58, pl. 2, fig. 13.

  • Uvigerina elongata Cole, in Stassen et al., 2015, p. 13, pl. 2, fig. 7.

Uvigerina rippensis Cole, 1927
Figs. 7.22, A2.21

    Uvigerina rippensis Cole, 1927
    Figs. 7.22, A2.21
  • Uvigerina rippensis Cole, 1927, p. 11, pl. 2, fig. 16.

  • Uvigerina rippensis Cole, in Charletta, 1980, p. 53, pl. 1, figs. 17.

  • Uvigerina rippensis Cole, in Stassen et al., 2015, p. 13, pl. 2, fig. 12.

Family ALABAMINIDAE

Genus Valvalabamina Brotzen, 1942
Valvalabamina depressa (Alth, 1850)
Figs. 6.1a–c, A1.16a–b, A3.15

    Genus Valvalabamina Brotzen, 1942
    Valvalabamina depressa (Alth, 1850)
    Figs. 6.1a–c, A1.16a–b, A3.15
  • Rotalina depressa Alth, 1850, p. 266, pl. 13, fig. 21.

  • Gyroidinoides imitata Olsson, 1960, p. 36, pl. 6, figs. 24.

  • Gyroidinoides octocamerata (Cushman & Hanna), in Charletta, 1980, p. 55, pl. 1, figs. 15–17.

  • Valvalabamina depressa (Alth), in Stassen et al., 2015, p. 13, pl. 2, figs. 20a–c

Family CACRISIDAE

Genus Valvulineria Cushman, 1926
Valvulineria group
Figs. 6.2a–c, A2.5a–b

    Genus Valvulineria Cushman, 1926
    Valvulineria group
    Figs. 6.2a–c, A2.5a–b

Note: All Valvulineria species are grouped due to low occurrences.

This research used samples of the U.S. Geological Survey (USGS). Financial support was provided by the FWO (12D6717N) to PS and by the KU Leuven Research Fund (C14/17/057) to RPS and PS. MMR was funded by the USGS Climate Research and Development Program. Graphs (excluding maps) were produced with R and the ggplot-package. We thank Lore Fondu (grain size analysis), Linde Vanlook (sample preparations, grain size measurements), and Oliver Kern (ggplot support). We also thank Jean Self-Trail and Whittney Spivey for their helpful comments on the manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. We would like to thank the two reviewers for their helpful and important input. Table A1 (raw counts of full assemblage data of benthic foraminifera and grain size data, South Dover Bridge) can be found linked to the online version of this article.

Supplementary data