Coastal geomorphological modification due to a superstorm around 3.9 thousand years ago has been documented through an integrated dataset comprising ground-penetrating radar (GPR) and lake sediment core records on a carbonate platform. The superstorm led to the formation of a storm-emplaced barrier, isolating a lagoonal marine embayment on Eleuthera Island, The Bahamas, resulting in the creation of a hypersaline lake basin. Originally, the area was a coastal mangrove swamp before the installation of the barrier. The lake basin developed on antecedent topography, with Pleistocene headlands bounding the embayment. Georadar surveys indicate that the barrier's origin was a single event, likely an intense storm. Shore-normal images reveal landward-sloping bounding surfaces and point-source reflections consistent with a surge barrier, in contrast to multiple beach-ridge sets of adjacent paleoshorelines. The recorded event falls within a global period of heightened storminess between 4100-3700 YBP, serving as a southern datapoint that complements Atlantic seaboard records. The preserved barrier suggests that its installation was followed by a sea-level stillstand after the postglacial rise, aligning with regional and global sea-level records. Post-impoundment, the saline coastal pond preserves a finely detailed hydroclimatic and hurricane record. These records indicate increased wetness in the Caribbean and Western Atlantic after 1300 cal BP, with a relatively stable period in the Bahamas from 1300 cal BP to approximately 300 cal BP. Hurricane proxy indicators reveal heightened activity between 3900 and 2000 cal BP, with additional spikes between 1100-1000 and 900-500 cal BP, coinciding with the Medieval Climate Anomaly. This study highlights the integration of geophysical and sedimentological data to reveal both stochastic and gradual processes shaping the evolution of coastal geomorphology.

The Moenave Formation of the Colorado Plateau region of western USA preserves the Triassic-Jurassic transition, a time period that saw one of the most significant climate disruptions in Earth’s history. During this time, major carbon (C)-cycle perturbations due to carbon release from the emplacement of the Central Atlantic Magmatic Province (CAMP) caused rapid climate change prompting the end-Triassic mass extinction (ETE). Here we present a Bayesian age-model generated from new C-isotope chemostratigraphic records paired with high-precision detrital zircon U-Pb geochronology to constrain the stratigraphic placement of the ETE and Triassic-Jurassic boundary within the Moenave Formation. Maximum depositional ages of detrital zircon from the Moenave Formation range between 203.71 ± 0.09 Ma to 200.20 ± 0.17 Ma. A −6.0‰ C-isotope excursion within the middle Dinosaur Canyon Member (DCM) is correlated to the initial negative C-isotope excursion of the ETE, indicating that the lower to middle DCM is latest Triassic and that climatic and biotic disturbances associated with CAMP should be preserved within this stratigraphic interval. Chemostratigraphic, geochronologic, and biostratigraphic data supports an earliest Jurassic age assignment for the lacustrine Whitmore Point Member, suggesting that it is an example of an earliest Jurassic ecosystem recovering from the ETE that warrants detailed exploration. This study greatly expands our knowledge of the chronostratigraphic framework of the continental Triassic-Jurassic transition and is important for correlating other global records of the ETE event.

We used pollen and charcoal analyses of sediments from two lakes at the southern end of Eleuthera Island, the Bahamas, to reconstruct vegetation and fire history over the past 5000 years. We obtained a 254-cm long sediment sequence from Shad Pond on the south end of Eleuthera near the coast. We obtained a 140-cm long sediment sequence from Duck Pond Blue Hole midway from either coast. Shad Pond sediment from 180 to 240 cm is fibrous peat dating from ~ 3800 to 4800 cal yr BP. The pollen spectrum in the peat is dominated by red mangrove ( Rhizophora mangle ) indicating the presence of a red mangrove swamp during this period. Duck Pond Blue Hole sediment from 100 to 140 cm is fine calcareous mud with only traces of pollen present. Palm pollen dominate the middle portion of both sediment sequences with pollen from rockland and coppice species also present. Palm pollen decline in both lakes ~ 1200 to 1300 cal yr BP, the start of Lucayan occupation. Palm pollen nearly disappear from Shad Pond sediments after ~ 1200 cal yr BP coincident with a spike in charcoal particles. Palm pollen drop by over one-half in Duck Pond Blue Hole after ~ 1200 cal yr BP, but there is only a small increase in charcoal particles. Palm pollen return in modest amounts toward the top of the Shad Pond sediments and there is a second, smaller peak in charcoal ~ 350 cal yr BP. This suggests a recovery of palms near the coast during the Plantation Period. Palm pollen gradually decline, charcoal increases, and pollen from disturbance species become very dominant toward the top of Duck Pond Blue Hole sediments after ~ 350 cal yr BP. The decline of palm pollen and increase in pollen from disturbance species in sediments from both sites ~ 1200 cal yr BP suggests heavy exploitation of palms by Lucayans, particularly near the coast. The later increase in charcoal and the significant increase in pollen from disturbance species in sediments from the inland Duck Pond Blue Hole site ~ 350 cal yr BP suggests inland land clearing during the Plantation Period.

We are living in a time of rapid biodiversity loss. Numerous studies have shown that modern extinction rates are higher than pre-human background rates. However, these studies of biodiversity decline almost exclusively focus on large vertebrates. The scientific community lacks the sufficient long-term records necessary to track biodiversity loss for many invertebrate taxa. However, aquatic, benthic, and skeletonized invertebrates have the advantage of leaving a long-term record that can readily be sampled in conjunction with living communities because the mineralized skeletons accumulate in the very same sediments in which the animals that produced them once lived. These not-quite-fossil “death assemblages” contain an underutilized record for long-term monitoring. Here, we leverage three case studies of calcareous micro- and macro-faunal remains from three aquatic environments spanning two gradients: freshwater to fully marine and polluted to pristine and remediated. We compared the death assemblages to living assemblages in these case studies using Spearman’s rho and the Jaccard–Chao agreement to determine the degree of fidelity. Death assemblages of lacustrine, calcareous microcrustaceans (Ostracoda), collected from lakes in The Bahamas and Wisconsin, USA, faithfully record human impacts, both for degradation and remediation, as determined by a mismatch in the live–dead comparisons. Likewise, the live–dead comparisons of calcareous marine macrofauna (Bivalvia) from the southern California shelf also indicate human impact, including pollution and remediation. These case studies demonstrate how death assemblages can be used to gauge the changes in community assembly and population structures at local and regional scales, even in the absence of a systemic monitoring program. Conservation, restoration, and biomonitoring efforts would benefit from the inclusion of live–dead comparisons of taxa with easily fossilized, identifiable parts. Live–dead studies, such as those presented in these case studies, can be used as tools for recognizing targets and establishing baselines for conservation, tracking community responses to remediation efforts, and identifying local species extinctions.

A new ostracod fauna was recovered and described from the Paleogene Claron Formation, famous worldwide for the "pink cliffs" of Bryce Canyon National Park and Cedar Breaks NationalMonument, in Utah, USA. The ostracods are from a section located along Sweetwater Creek in Garfield County that also contains gastropods, ichnofossils, algal impressions, charophytes and vertebrates. This diverse, freshwater lacustrine ostracod fauna contains the following 12 species: Paracandona rosaepraeceps n. sp., Candona artesensis, Cyclocypris (Laevicypris) eaglespringsensis, Cyclocypris (Leucocypris) trapezoidalis, Cypris pagei, Scottia subquadrata, Timiriasevia changzhouensis, Heterocypris whiteriverensis? Cypris? sp. 1, Djungarica? sp. 1, Gen. aff. Bisulcocypridea sp. 1 and Pseudocandona sp. 1. The presence of a mixed assemblage of strictly early Eocene ostracod species and others with a wider stratigraphic distribution suggests that the base of the Sweetwater Creek section might extend into the Paleocene, which agrees with previous observation of Paleocene charophyte taxa in basal strata of the Sweetwater Creek section.

Elizabeth Gierlowski-Kordesch (1956–2016) was a leader and innovator in the specialty field of limnogeology since its beginnings in the late 1980s. Her excitement for field work and examining sediments was contagious, and she was always testing new research ideas. Beth would have been thrilled with the diversity of papers presented in the volume and the wide array of techniques used to determine the history, geochemistry, paleontology, and paleoclimate preserved in the sediments in basins that are located on every continent except Australia and Antarctica. She would also have been delighted that half the chapters were first authored by highly cited women scientists. Beth spent her career teaching, mentoring, conducting research with students and colleagues, and planning limnogeology conferences, books, and field trips. Her contributions span deep-time lakes from North and South America, Africa, Asia, and Europe, starting with her work on the Lower Jurassic East Berlin Formation where she conducted her Ph.D. research. Her work with Kerry Kelts at the University of Minnesota produced two books summarizing global lake research. These volumes are still used by many researchers, particularly as a starting point in their limnogeological studies. Her collaboration with Springer Nature® resulted in the series entitled Syntheses in Limnogeology, a publication that likely would not exist without her enthusiasm and perseverance. The papers in this second volume in the series describe a variety of Jurassic to modern lakes that range from fresh to hypersaline, shallow to deep, vary in size from <1 km2 to 100s of km2, and are found in a number of tectonic settings. Various proxies, including microfossils and trace fossils and analyses of lacustrine sedimentology, stratigraphy, and stable isotopes are used to evaluate the sediment cores and stratigraphic sections to evaluate human and climate influences on the environment, the effects of tectonic, seismic, and volcanic activity, and variations in hydrology. The contributions in this volume reflect the diverse research that Beth conducted herself and we hope is a fitting honor to one of the founding scientists of Limnogeology.

One of the most perplexing questions within evolutionary biology is: "why are there so many methods of reproduction?" Contemporary theories assume that sexual reproduction should allow long term survival as dispersal and recombination of genetic material provides a population of organisms with the ability to adapt to environmental change. One of the most frustrating aspects of studying the evolution of reproductive systems is that we have not yet been able to utilize information locked within the fossil record to assess breeding system evolution in deep time. While the fossil record provides us with information on an organism's living environment, as well as some aspects of its ecology, the preservation of biological interactions (reproduction, feeding, symbiosis, communication) is exceedingly rare. Using both information from extant taxa uncovered by a plethora of biological and ecological studies and the rich representation of the Spinicaudata (Branchiopoda: Crustacea) throughout the fossil record (from the Devonian to today), we address two hypotheses of reproductive evolutionary theory: (1) that unisexual species should be short lived and less speciose than their outcrossing counterparts and (2) that androdioecy (mixtures of males and hermaphrodites) is an unstable, transitionary system that should not persist over long periods of time. We find no evidence of all-unisexual spinicaudatan taxa (clam shrimp) in the fossil record, but do find evidence of both androdioecious and dioecious clam shrimp. We find that clades with many androdioecious species are less speciose but persist longer than their mostly dioecious counterparts. These data suggest that all-unisexual lineages likely do not persist long whereas mixtures of unisexual and sexual breeding can persist for evolutionarily long periods but tend to produce fewer species than mostly sexual breeding.

The Eocene Green River Formation is one of the best-known Konservat lagerstätten and comprises lacustrine strata that were deposited during the Early Eocene Climatic Optimum (EECO). Two species of ostracodes, Pseudoeucypris pagei (Swain, Journal of Paleontology, 23:172–181, 1949) and Hemicyprinotus watsonensis (Swain, Journal of Paleontology, 23:172–181, 1949), were recovered from 16 intervals at three sites from Fossil Basin, Wyoming, USA. Population density per sample was quantified as the number of ostracode valves per cm2. Analysis of kerogen content shows a significant difference between preservation based upon lithology, with ostracodes being more commonly preserved in kerogen-poor micrites but more abundant when preserved in kerogen-rich micrites. The nature of preservation also was correlated to lithology with ostracodes being preserved as whole carapaces more frequently in kerogen-poor micrites and being more broken and disarticulated in kerogen-rich micrites. Species tracked lithology as well, with the epiphytic species P. pagei occurring exclusively in kerogen-poor micrites and dolomicrites, while the benthic species H. watsonenis occurred in kerogen-rich micrites as well as some kerogen-poor micrites. The present study demonstrates how ostracodes are preserved differently within the basin and the utility of species occurrences in tracking changing lake environments, as similarly reported in other Green River Formation basins. Here, we interpret that the presence of P. pagei and the rocks it is preserved in indicate shallower lake conditions, while shifts to H. watsonensis are indicative of deepening lake conditions.

The Neogene and Quaternary are characterized by enormous changes in global climate and environments, including global cooling and the establishment of northern high-latitude glaciers. These changes reshaped global ecosystems, including the emergence of tropical dry forests and savannahs that are found in Africa today, which in turn may have influenced the evolution of humans and their ancestors. However, despite decades of research we lack long, continuous, well-resolved records of tropical climate, ecosystem changes, and surface processes necessary to understand their interactions and influences on evolutionary processes. Lake Tanganyika, Africa, contains the most continuous, long continental climate record from the mid-Miocene (∼10 Ma) to the present anywhere in the tropics and has long been recognized as a top-priority site for scientific drilling. The lake is surrounded by the Miombo woodlands, part of the largest dry tropical biome on Earth. Lake Tanganyika also harbors incredibly diverse endemic biota and an entirely unexplored deep microbial biosphere, and it provides textbook examples of rift segmentation, fault behavior, and associated surface processes. To evaluate the interdisciplinary scientific opportunities that an ICDP drilling program at Lake Tanganyika could offer, more than 70 scientists representing 12 countries and a variety of scientific disciplines met in Dar es Salaam, Tanzania, in June 2019. The team developed key research objectives in basin evolution, source-to-sink sedimentology, organismal evolution, geomicrobiology, paleoclimatology, paleolimnology, terrestrial paleoecology, paleoanthropology, and geochronology to be addressed through scientific drilling on Lake Tanganyika. They also identified drilling targets and strategies, logistical challenges, and education and capacity building programs to be carried out through the project. Participants concluded that a drilling program at Lake Tanganyika would produce the first continuous Miocene–present record from the tropics, transforming our understanding of global environmental change, the environmental context of human origins in Africa, and providing a detailed window into the dynamics, tempo and mode of biological diversification and adaptive radiations.