Home range of the Columbian mammoths (Mammuthus columbi) and grazing herbivores from the Waco Mammoth National Monument, (Texas, USA) based on strontium isotope ratios from tooth enamel bioapatite Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): D. Esker, S.L. Forman, C. Widga, J.D. Walker, J.E. Andrew Abstract Waco Mammoth National Monument (WMNM) is a central Texas, Late Pleistocene fossil site dating to ~67 ka. At least 23 Columbian mammoths (Mammuthus columbi), along with the remains of 12 other vertebrate genera have been discovered at this locality. Mammoth teeth were micro-sampled at a high resolution with a computerized micromill, whereas bison and horse teeth were serially sampled with a handheld rotary tool. Serial samples from these individuals offer insights into the movement patterns (87Sr/86Sr) of WMNM herbivores. Regional vegetation and local sediments were also collected to construct an 87Sr/86Sr isoscape to track past movement of mammals, derived from Sr analyses of teeth enamel. 87Sr/86Sr in WMNM herbivores often reflects multiple grazing provenances, and sources. A series of mixing models are proposed to understand the contribution of different surface Sr sources to herbivore diets. These data indicate one mammoth spent some time at the Llano uplift area ~180 km to the SSW during the formation of molar enamel. The remaining individuals (three mammoths, a bison and a horse) lived in an area more proximal to the WMNM, ≤70 km SE of the site. 87Sr/86Sr from WMNM mammoths indicate individual fidelity to at least two geographic ranges, with at least one mammoth, potentially unrelated to the possible matriarchal herd, indicating complex population dynamics prior to mass mortality. This analysis shows that at least 25 mammals, including the horse and bison, congregated at the confluence of Brazos and Bosque rivers at ~67 ka ago, prior to their demise. A resource shortage related to drought is consistent with this pattern.

Aragonite pteropod abundance and preservation records from the Maldives, equatorial Indian Ocean: Inferences on past oceanic carbonate saturation and dissolution events Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): E. Sreevidya, A.V. Sijinkumar, B. Nagender Nath Abstract During the International Ocean Discovery Program (IODP) Expedition 359, a long continuous carbonate-rich sequence was recovered from the Inner Sea of Maldives. We investigated pteropod proxies (absolute abundance of pteropods species, total pteropods, epipelagic to mesopelagic ratio, fragmentation ratio, Limacina Dissolution Index (LDX), mean shell size variations of L. inflata) from Sites U1467 (water depth: 487 m) and U1468 (water depth: 521 m) to understand both surface and sub-surface paleoceanographic changes in the equatorial Indian Ocean and to improve our understanding of the factors responsible for pteropod preservation on longer timescales. A total of 15 species of pteropods were identified, and their downcore variations were documented from the core top to 707.49 mbsf in U1467 and from 447.4 to 846.92 mbsf in U1468. At the Site U1467, pteropod shells show high abundances/preservation up to a depth of 45 mbsf (~1.2 Ma), which is consistent with the presence of aragonite content in sediments (with the top 50 m bearing high aragonite content). Beyond 45 mbsf, only fragmented pteropod shells were seen down to 50 mbsf (corresponding to 1.5 Ma) followed by a total absence of pteropod shells and fragments from 50 mbsf (~1.5 Ma) to the end of the core at 846.92 mbsf (~24 Ma). A decrease in the SO42ˉconcentration and alkalinity in the interstitial fluid geochemistry is seen at these depths. The presence of dolomite content below 50 mbsf also indicates the alteration of aragonite into dolomite. Analyses of the carbonate preservation proxies reveal that the pteropods exhibit considerable fluctuation in abundance/preservation during the last 1.2 Myr. A good to moderate preservation (LDX: 2 to 3) is seen which correlates well with the fragmentation ratio but with an inverse relation with calcification rate. The proxies for in-life pteropod shell dissolution (average size of L. inflata and LDX) indicate that glacial periods (MIS 16, 14, 6, 4 and 2) have shown no signs of dissolution pointing better calcification under aragonite-saturated water column which is in good correlation with reduced atmospheric CO₂ concentration. Epipelagic/mesopelagic ratio indicates that the water column exhibited enhanced ventilation and mixing during glacial to interglacial periods, but intervals of intense stratification, a sign of poor ventilation or weakened circulation, was prevalent beyond MIS 14. The longest interval of poorest preservation was marked during MIS 11 and 13, which corresponds to the ‘Mid-Brunhes Dissolution Interval (MBDI).’ On a longer time scale, the abundances/preservation of pteropods in the Maldives seems to be controlled by changes in the seawater chemistry associated with monsoon productivity, water column ventilation, and atmospheric CO2concentration.

Bioerosion on vertebrate remains from the Upper Cretaceous of the Haţeg Basin, Romania and its taphonomic implications Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): Felix J. Augustin, Andreas T. Matzke, Zoltán Csiki-Sava, Hans-Ulrich Pfretzschner Abstract Bioerosion on fossil bones offers significant insights into both trophic relationships of ancient ecosystems and vertebrate taphonomy. Here we report six distinct trace fossil categories identified on isolated turtle, crocodyliform and dinosaur remains from the Upper Cretaceous Sînpetru Formation of the Haţeg Basin (Romania), for which five different probable tracemakers are identified: (1) termites, (2) dermestid beetles, (3) multituberculate mammals, (4) ziphodont theropod dinosaurs or crocodyliforms, and (5) plants. This extraordinary diversity of bioerosional trace fossils on vertebrate remains reveals insect-vertebrate as well as vertebrate-vertebrate interactions previously undocumented in the continental uppermost Cretaceous of Romania. The association between different traces, especially since many of these are superimposed on top of each other, allows the reconstruction of the detailed taphonomic history of the specimens, indicating four different taphonomic pathways. The vertebrate remains with trace fossils described here were most likely exposed to post-mortem biotic interactions for a prolonged time period before they were transported and/or trampled and finally buried. In the palaeoenvironmental context of a heterogeneous braided river system with low-lying wetlands and more elevated drylands, the death of the vertebrates as well as the scavenging likely occurred on the drylands.

Decoding sea surface and paleoclimate conditions in the eastern Mediterranean over the Tortonian-Messinian Transition Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): G. Kontakiotis, E. Besiou, A. Antonarakou, S.D. Zarkogiannis, A. Kostis, P.G. Mortyn, P. Moissette, J.-J. Cornée, C. Schulbert, H. Drinia, G. Anastasakis, V. Karakitsios Abstract New sedimentological, micropaleontological and geochemical data from the Upper Miocene pre-evaporitic sedimentary sequence of the Faneromeni section (Crete Island, eastern Mediterranean) revealed a stepwise restriction of the Mediterranean Sea preceding the Messinian Salinity Crisis (MSC), which was modulated by a sedimentary cyclicity responding to orbital parameters. This cyclicity is manifested by lithological alternations from laminated to indurated homogeneous marls and clayey limestones, and covers the Tortonian-Messinian Transition (TMT; 7.6–6.7 Ma). This time window covers the successive closure of the marine Mediterranean-Atlantic gateways, which culminated in the onset of the MSC. In the present study, we present the first evidence for changes in the upper water column reflected by sea surface temperature (SST) and salinity (SSS) variations that correlate with pronounced paleoclimatic fluctuations. Planktonic foraminiferal isotopes, in combination with paired mixed layer Sr/Ca-derived SST data, reveal that the very warm late Tortonian interval has been followed by a strong long-term cooling (~10 °C) and desalination (~10‰) trend during the earliest Messinian, attributed to the paroxysmal phase of the so-called “siphon” event. In particular, the climate shift that occurred at the end of a global carbon isotope (δ13C) decrease suggests that changes in the carbon cycle were instrumental in driving late Miocene climate dynamics (cooling and aridity) in the progressively isolated eastern Mediterranean Sea. The observed salinity variability during this time interval also provides further insights about seasonal freshwater inputs and gives new support to the much-debated hydrologic regime (linear salinity increase vs step-function evolution with strong salinity fluctuations) preceding the deposition of evaporites. The novel methodology of foraminiferal Sr/Ca paleothermometry and results of this study could have numerous potential applications to other regions and relevant extreme geological events. Therefore, in the near future we expect this approach to add important new information to our understanding of Neogene climates.

Ecological snapshot of a population of Panopea within their traces (Pliocene, Agua Amarga subbasin, SE Spain) Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): Weronika Łaska, Francisco J. Rodríguez-Tovar, Alfred Uchman, Julio Aguirre Abstract Pliocene deposits cropping out in the Agua Amarga subbasin (Almería, SE Spain) include a composite shell bed made up of variously preserved and densely packed mollusks. The characteristics of the shell bed indicate deposition in shallow marine settings under a changeable sedimentation rate. The composite shell bed was formed through the amalgamation of several depositional events, mostly connected with storm events. During relatively slow sedimentation the bivalve Panopea colonized the substratum. The colonization took place over different stages of the shell bed formation, as reflected by differently preserved Panopea scattered throughout the shell bed. The upper part of the shell bed contains several tens of Panopea preserved within their burrows: Scalichnus cf. phiale Hanken et al., 2001. All bivalves in S. cf. phiale are articulated and preserved in life position. They are confined to a single horizon and most probably represent a single fossil population composed of adult individuals of Panopea resulting from anastrophic burial by storm deposits. As a consequence, the bivalves in their burrows succumbed at the same time; that is, the study case represents an “ecological snapshot” or ecological census.

Sulfate-controlled marine euxinia in the semi-restricted inner Yangtze Sea (South China) during the Ordovician-Silurian transition Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): Na Li, Chao Li, Junxuan Fan, Thomas J. Algeo, Detian Yan, Guangyou Zhu, Shiyong Wu, Shida Tang, Meng Cheng, Chengsheng Jin Abstract Conflicting published interpretations of marine redox conditions during the Ordovician-Silurian transition (OST) may have been linked to spatial redox heterogeneity during this interval. However, details of the pattern of redox heterogeneity and its underlying causes remain unclear. Here, we present a high-resolution geochemical study of a drillcore section (Pengye #1) from Pengshui County (Chongqing municipality, southwestern China) that was located in the semi-restricted inner Yangtze Sea during the OST. We analyzed Fe-speciation, redox-sensitive trace elements, major elements, and pyrite δ34S compositions (δ34Spy) and then compared these data with published results from coeval sections at Datianba and Shuanghe in the same basin. The integrated dataset demonstrates pronounced spatiotemporal heterogeneity of redox conditions—especially the local development of euxinic conditions in the inner Yangtze Sea during the OST. Integrated data further suggest that high primary productivity and ample Fe fluxes in the inner Yangtze Sea may have depleted dissolved sulfate through microbial sulfate reduction (MSR) and subsequent pyrite formation, except in areas with enhanced sulfate supply from continental weathering or open-ocean exchange, which varied as a function of both tectonic (i.e., the regional Kwangsian Orogeny) and eustatic changes (i.e., the global Hirnantian glaciation). Limited sulfate availability thus likely prevented the development of euxinic conditions in some regions of the inner Yangtze Sea, as reflected in spatial variation of δ34Spy. Our study highlights the potential role of sulfate availability on the development of watermass euxinia in semi-restricted marginal-marine basins during the OST.

Latest Devonian (Famennian, expansa Zone) conodonts and sponge-microbe symbionts in Pinyon Peak Limestone, Star Range, southwestern Utah, lead to reevaluation of global Dasberg Event Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): Carl W. Stock, Charles A. Sandberg Abstract We document the signature of the late Famennian (Early expansa Zone) multi-phase Dasberg Event, previously termed ALFIE, in Utah and Colorado. The Dasberg was a major event, not a crisis, because it resulted from a eustatic rise that introduced the Etroeungt fauna, consisting of large solitary rugose corals and unusually large brachiopods, from an as yet undiscovered refugium. This “Lazarus” fauna was short-lived; it disappeared within a few million years, as a result of the more intensely studied end-Devonian (D—C) Hangenberg Extinction Event. Our research centers on a meter-thick sponge-microbe symbiont bed at the top of the lower member of the Pinyon Peak Limestone at Elephant Canyon, Star Range, southwestern Utah, USA, which formed during an early phase of the Dasberg Event. This “disaster” bed is well dated by conodont faunas in beds just below and just above. Superficially resembling stromatolites, the meter-thick symbiont bed contains microscopically interlayered sponges and microbialites. Occurring with the symbionts are bryozoans, brachiopods, and megascopic stromatoporoid sponges. This is arguably the first reported occurrence of late Famennian stromatoporoids in North America. Mounds at the top of the biostrome represent the last growth stage of the biostrome, which was arrested by development of a bored hardground. The mounds, which contain the same biota as the symbiont bed, were bored by unknown organisms. By combining our findings at Elephant Canyon with known data on Devonian ∂13C positive excursions, we determined that the biostrome developed at a time of warming during the otherwise cool late Famennian. The presence of a stromatolite-like symbiont bed is suggestive of an extinction event, especially as the environment of deposition represents shallow water, but with normal salinity, allowing growth of a diverse biota. Conodont faunas of the Pinyon Peak Limestone in the Star Range were pivotal in development of a late Famennian conodont biofacies model. Our re-dating of conodont faunas enables an improved correlation of the ∂13C curve between localities in Utah and Colorado.

High-resolution seismic stratigraphy of Late Pleistocene Glacial Lake Iroquois and its Holocene successor: Oneida Lake, New York Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): Nicholas J. Zaremba, Christopher A. Scholz Abstract Oneida Lake, New York, is the remnant of Glacial Lake Iroquois, a large proglacial lake that delivered fresh water to the Atlantic Ocean during the last deglaciation. The formation of Glacial Lake Iroquois and its subsequent drainage into the Atlantic Ocean via the Mohawk Valley was a significant shift in the routing of Laurentide Ice Sheet meltwater to the east instead of south via the Allegheny or Susquehanna Rivers. Catastrophic drainage of Glacial Lake Iroquois into the Atlantic Ocean via the Champlain Valley is interpreted as the meltwater pulse responsible for the Intra-Allerod cold stadial. Therefore, understanding the evolution of Glacial Lake Iroquois has significant implications for understanding late Pleistocene paleoclimate. High-resolution CHIRP seismic reflection data provides insight into the evolution of Glacial Lake Iroquois and Oneida Lake. Three seismic units image distinct stages of the Oneida Basin. Unit 1 is interpreted as proglacial lake deposits that overlie glacial till. Unit 2 is interpreted as sediments deposited when the Oneida Basin became isolated from Glacial Lake Iroquois and Unit 3 is interpreted as lacustrine sediments of the modern lake. Distally sourced turbidites possibly triggered by seismic activity or ice sheet meltwater pulses are represented as reflection-free acoustic facies that infill topographic lows and range in thickness from ~1–5 m within otherwise conformable proglacial lake deposits. Local slump deposits imaged at the boundary between Unit 1 and 2 were likely triggered by the drainage of Glacial Lake Iroquois. Wave cut terraces indicative of a low stand on the upper bounding surface of Unit 2 are likely the result of drier conditions during the Holocene Hypsithermal. Furthermore, preservation of this low stand suggests a rapid rise in lake level, possibly the result of the same transition to a wetter climate responsible for the Nipissing transgression observed in the Laurentian Great lakes.

Rhenium‑osmium geochronology of the Toarcian Posidonia Shale, SW Germany Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): D. van Acken, T. Tütken, J.S. Daly, A. Schmid-Röhl, P.J. Orr Abstract Black shale samples from sedimentary layers below and between the Unterer Stein, Oberer Stein, Inoceramus Bank, and Nagelkalk horizons from the Dormettingen quarry, SW Germany were analysed for their Re and Os isotope composition and content. The ~12-m-thick sedimentary sequence of the Posidonia Shale Formation, composed of multiple layers of black shale and intercalated limestone beds, was deposited during the Early Jurassic (Toarcian), a time during which black shale sedimentation was ubiquitous in Western Europe during a widespread oceanic anoxic event. Both the marl and shale layers beneath the black shales and adjacent to the Oberer Stein limestone layer show signs of bioturbation. The excellent biostratigraphic constraints and the high Re and Os contents (24–290 ppb and 290–1050 ppt, respectively) of the Dormettingen shales thus make these samples ideal for testing the influence of bioturbation on the Re-Os isotope system, as well as refining age constraints for the Toarcian OAE and potential triggers for this event. The calculated isochron age for the Dormettingen shales is 183.0 ± 2.0 Ma, with a low initial 187Os/188Osi of 0.377 ± 0.065, indicating a Pliensbachian to Toarcian age. This age is in agreement with published U-Pb and Re-Os ages for other Lower Jurassic sites, astronomical constraints, and biostratigraphic correlations, suggesting limited disturbance of the isotope system by minor degrees of biological activity. The low 187Os/188Osi is consistent with significant influx of mantle-derived material into the Toarcian ocean, likely from weathering of Karoo-Ferrar Large Igneous Province basalts.

The last phylum: Occupation of Bryozoa morpho-ecospace (colony growth habits) during the early phase of the Great Ordovician Biodiversification Event Publication date: 15 November 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 534 Author(s): Steven J. Hageman, Andrej Ernst Abstract Most major phyla, and all skeletonized phyla have their first appearance in the Cambrian. The exception is the Phylum Bryozoa, which first appear in the Early Ordovician (Tremadocian 1b). Bryozoans have an excellent fossil record, due in part to their benthic marine habitat with skeletal colonies composed largely of stable, low-Magnesium calcite. These factors provide an unrivaled opportunity to observe patterns and rates of radiation of a new phylum into disparate morpho- ecospace through the Great Ordovician Biodiversification Event (GOBE). In this study, the colonial growth habits of all known skeletonized Bryozoa (181 species) from the Early and Middle Ordovician are characterized in a new classification scheme based on processes of growth, rather than their end geometry as most traditional classifications of bryozoan growth habits. These fundamental categories are: orientation, dimensions of primary growth, width of colony unit, layers of zooecia, substrate relationships, space utilization, skeleton mineralization, plus sub-categories of orientation based on their geometry. In the Early and Middle Ordovician there are 85 unique growth habits defined by these eight growth habit characters. By the end of Middle Ordovician, about 4.8% of the morpho-ecospace defined by two subsets of the characters had been occupied by five bryozoan orders (represented by 34 families, 77 genera). When plotted by Ordovician stage time-slices (ca. 2.2 my each), a sharp increase in taxonomic and growth habit occurrence is observed at the Early-Middle Ordovician transition, earlier than in other groups. Individual growth habit character states also show significant changes at this transition. In the Early Ordovician, low bryozoan taxonomic and growth habit richness is due in part to sampling bias and modified search methods are need, however, the overall patterns (Early-Mid. Ordovician transition) observed in this study are robust and not expected to change fundamentally with additional data.