Fossil Shells Research Articles

Early Cambrian microfossils from the cherts in carbonates of the Kuruktag area, the Tarim block

The basal Cambrian is characteristic for the appearance of small shelly fossils and acanthomorphic acritarchs with relatively small vesicles. In the Tarim Block (NW China) and South China, this microfossil assemblage is dominated by small acanthomorphs and was referred to as the ‘Micrhystridium-Paracymatiosphaera-Megathrix’ (MPM) association, based on microfossils from the lower Cambrian Yurtus and Xishanblaq formations of the Tarim Block. This study provides the new early Cambrian microfossil assemblage preserved in cherts of carbonates in Tikebuladahuang section of the Kruktag area, Tarim Block. These early Cambrian microfossil assemblages come from upper part of the lower Cambrian Xishanblaq Formation in Tikebuladahuang section correlated with the Cambrian Stage 2, and the microfossil association dominated by Heliosphaeridium dissimilare, sponge spicules, Leiosphaeridia spp., and Siphonophycus sp. also occurs. The organic-walled microfossil assemblage found in this study can be compared with the microfossils in the early Cambrian Chert of the Yangtze plate. The Asteridium–Heliosphaeridium–Comasphaeridium (AHC) association in South China and the Tarim block may mix two fossil associations of different ages and fossil compositions.

Daily growth rate variation in Tridacna shells as a record of tropical cyclones in the South China Sea: Palaeoecological implications

Tropical cyclones (TC) are one of the most destructive weather phenomena on Earth. However, the short duration of instrumental weather records mean that little is known of the frequency of TCs through geological time. Here we analyse a Tridacna squamosa shell with a life span about 6 years (from 12 May 2013 to 18 December 2018) from the northern South China Sea. Studies of daily growth rate variations (DGRV) were correlated with coeval environmental changes to develop a proxy for TC. Results reveal that the frequency and variation of extreme DGRV were conspicuously different between the typhoon-affected season (July to October) and relatively stable growth season (March to June). During the typhoon-affected season, the frequency of sudden onset of decreased sea surface temperature, attenuated solar radiation and heavy precipitation can result in more days for extreme decreases of DGRV. On interannual timescale, the frequency of extreme DGRV was significantly correlated with TC influence days. Our findings indicate that the frequency of extreme DGRV profile in Tridacna squamosa shells has potential to be a novel recorder for past TC activity. We conclude that fossil shells in different geological eras offer the potential to extend modern instrumental datasets and provide opportunities for investigating TC activity in response to past and future global change.

Aldanella attleborensis (Mollusca) from Cambrian Stage 2 of the Three Gorges Area and Its Stratigraphic Implications.

Some small shelly fossils are important index fossils for global stratigraphic subdivisions and correlations of the Cambrian Terreneuvian. The first appearance datum (FAD) of the cosmopolitan mollusk Aldanella attleborensis has been suggested as one of the potential markers for defining the base of Cambrian Stage 2. Aldanella fossils were uncommon in South China, and if occurring, were often described as Aldanella yanjiaheensis, A. attleborensis, or indeterminate species in the literature, while A. yanjiaheensis was often taken as a junior synonym of A. attleborensis. Nevertheless, a detailed taxonomic revision of A. yanjiaheensis based on material from its type locality awaits to be made. In this study, we systematically re-evaluated A. yanjiaheensis based on the numerous specimens collected from the base of Member 5 of the Yanjiahe Formation in the Three Gorges area, western Hubei Province of South China. Detailed taxonomic comparison further substantiates that A. yanjiaheensis is a junior synonym of A. attleborensis, signifying its strong potential for a global correlation across paleocontinents. Morphological parameter analyses indicate that the length and width of shell tube of A. attleborensis shows allometric growth. The nearly cosmopolitan distribution and characteristic morphology of A. attleborensis indicate that it can play a significant role in the subdivision and correlation of Cambrian Stage 2. The co-occurrence of A. attleborensis and Watsonella crosbyi from the base of Member 5 of the Yanjiahe Formation corroborates that Member 5 belongs to Cambrian Stage 2.

Clumped and oxygen isotope sclerochronology methods tested in the bivalve Lucina pensylvanica

Geochemical signatures preserved within the geologic record can be used to reconstruct past mean temperature and seasonality, but in order to accurately apply any geochemical proxy method in the past, a rigorous study of how the recorded proxy is related to temperature in the modern setting must be conducted. Here, we assess the ability of multiple isotope techniques to correctly record mean annual temperature and seasonality in the bivalve Lucina pensylvanica. We compare subannual-resolution δ18O-based, seasonally-targeted and continuous high-resolution (H.R.) clumped isotope (Δ47)-based thermometry methods, as well as multiple data treatment methods for each, to determine which approach best matches known modern temperatures (maximum and minimum absolute temperature and annual temperature range), with the goal of defining the ideal sampling scheme for use on fossil shells. In L. pensylvanica shells collected from 7 sites, we observe neither mean temperature nor seasonal biases. Mean annual temperature is best matched by averaging all seasonally-targeted Δ47-temperatures. Seasonality is best matched by averaging δ18Ocarb-based temperatures from all summers and all winters before taking the difference. Of two data treatment approaches applied to the continuous high-resolution Δ47-based temperatures, “data optimization” is apparently better at resolving smaller seasonal temperature differences. In contrast, “data smoothing” produces a temperature record unbiased by prior assignment of seasonal extremes and has the simultaneous ability to detect subannual variability in δ18Ow. However, accurate application of H.R. Δ47 methods must balance sampling resolution and growth rate. If sampling resolution is high enough relative to the growth rate (∼1 pt./month or better), we recommend continuous high-resolution Δ47-thermometry with data smoothing. If this resolution cannot be achieved due to slow growth rates or insufficient shell size, we recommend pairing subannual δ18Ocarb-based and seasonally-targeted Δ47-based temperature reconstruction to acquire seasonal range in temperature and absolute temperature extremes.

In both directions: Expansions of European land snails to the north and south from glacial refugia

AbstractAimWere postglacial recolonizations facilitated by persistence close to the colonized areas rather than by dispersal ability allowing for colonization from distant sources? This question is particularly relevant for organisms with low active dispersal abilities and lacking specialized propagules. Here we identified glacial refugia of four Central European land snail species, including one for which a northern glacial refugium in the region was indicated by indirectly dated fossils.LocationCentral Europe and the Balkans.TaxonPulmonate land snails: Monachoides incarnatus (Hygromiidae) and Helix pomatia, Helix thessalica and Caucasotachea vindobonensis (Helicidae).MethodsWe used continuous phylogeographic analysis of mitochondrial sequence data to trace the origin of postglacially expanding lineages. We assessed the credibility of results from our focal species, M. incarnatus, by comparison to three other broadly sympatric land snail species. In addition, we performed direct radiocarbon dating of fossil shells to verify the presumed glacial presence of M. incarnatus on the territories of Czechia and Slovakia and to test the reliability of the available fossil data.ResultsIn three of the four species, the molecular data supported refugia located south of the Pannonian Basin, from the south‐eastern Alps to the south‐western Carpathians, but not more northerly. The direct radiocarbon dating resulted in younger dates than previously assumed. However, the molecular data also revealed unexpected, yet substantial postglacial southward expansions of M. incarnatus and C. vindobonensis into the Balkans.Main ConclusionsNeither the phylogeographic analyses nor the direct radiocarbon dating provided evidence for the glacial survival of studied land snail species in Central Europe. The refugia located adjacent to the Pannonian Basin were the most important source of postglacial expansions to Central Europe, but were also the source of the expansion southwards. Both climatic factors and biological interactions might explain why such southward expansions seem rather rare in Europe.

The management of symbolic raw materials in the Late Upper Paleolithic of South-Western France: a shell ornaments perspective

Personal ornaments manufactured on marine and fossil shell are a significant element of Upper Palaeolithic symbolic material culture, and are often found at considerable distances from Pleistocene coastlines or relevant fossil deposits. Here, we report on a significant collection of shell objects (n=377) from the Upper Magdalenian site of Rochereil (Dordogne, France). Despite the location of the site at more than 200km from the Pleistocene coast, the majority of the shells recovered here are unmodified, suggesting that transport and accumulation of shell raw material was an important component in the production of symbolic technologies some 16 15,000 years ago. A detailed comparative and microscopic reanalysis of this assemblage explores which species were selected, examines technological and taphonomic modification of the material, and compares this collection with the use of similar shell ornaments in the wider Magdalenian world.

Coal quality, mineralogy, petrography, and geochemistry of the high-strontium Parçikan lignite

The Parçikan coalfield hosts a late Miocene 1.1-m thick coal seam. This study aims to determine coal quality, mineralogy, petrography and geochemistry, and controlling factors of elemental enrichments. The coals are generally black and greyish black in colour, and the low part of the seam commonly includes fossil shell remains. The ash yield displays a decreasing trend towards the upper part of the seam; in turn, gross calorific and total C values increase upwards. The total S content being generally higher than 5% (on dry basis), displays an increasing trend towards the upper part. In the entire seam, huminite is the most common maceral group, while inertinite and liptinite display variable proportions. The identified minerals by XRD are mainly quartz, clay minerals, calcite, pyrite, and aragonite (in fossil shell remains-bearing samples), whereas feldspars and marcasite determined in a few samples. Furthermore, in the coal samples, celestine and barite were identified by SEM-EDX. This study indicates that precipitation of celestine and Sr-bearing barite grains during diagenetic stage and Sr-uptake by mollusc within the palaeomire caused Sr enrichment in the entire seam. Overall, the water influx and redox conditions controlled the mineralogical and the elemental compositions of the coal seam.

Giant clam (Tridacna) distribution in the Gulf of Oman in relation to past and future climate

The Oman upwelling zone (OUZ) creates an unfavorable environment and a major biogeographic barrier for many coral reef species, such as giant clams, thus promoting and maintaining faunal differences among reefs on the east and west side of the Arabian Peninsula. We record the former existence of Tridacna in the Gulf of Oman and review its stratigraphic distribution in the Persian Gulf to provide new insights on the connectivity of coral reef habitats around southern Arabia under changing climate and ocean conditions. Fossil shells were carbon-14 dated and employed as sclerochronological proxy archives. This reveals that the Omani population represents a last glacial colonization event during the Marine Isotope Stage 3 interstadial under colder-than-present temperatures and variable upwelling intensity linked to Dansgaard-Oeschger climate oscillations. It was favored by temperatures just above the lower threshold for the habitat-forming reef coral communities and instability of the upwelling barrier. We conclude that the distribution of Tridacna in the northern Arabian Sea is generally limited by either strong upwelling or cool sea surface temperature under gradually changing climate conditions at the interglacial-glacial scale. Opportunities for dispersal and temporary colonization existed only when there was a simultaneous attenuation of both limiting factors due to high-frequency climate variability. The OUZ will unlikely become a future climate change refuge for giant clams because they will be exposed either to thermal stress by rapid anthropogenic Indian Ocean warming or to unfavorable upwelling conditions.

Hydrodynamic Simulations of Millimeter‐Scale Cambrian Sedentary Medusozoans

AbstractModern medusae are primarily macroscopic, free‐swimming marine organisms with a tetraradial symmetry. But the early Cambrian medusozoans, such as biradial Hexaconularia sichuanensis and tetraradial Quadrapyrgites quadratacris from the basal Cambrian Kuanchuanpu Formation in South China, were millimeter‐scale and sedentary forms. Although well‐documented as common components in a shelf environment, little is known about their in situ life conditions since they are easily transported by tidal flow before burial. Specifically, the interactions between their exoskeleton shapes and the hydrodynamic conditions are poorly known. Here we use fluid–structure interaction computational fluid dynamics to analyze the functional performance of the two taxa using 3D mesh models constructed from scanned fossils. The simulation experiments reveal that: (a) due to their millimeter‐scale size, most sedentary small shelly fossils (SSFs), including those of medusozoans lived within the viscous sublayer range of tidal flow; (b) the biradial symmetry of Hexaconularia was more structurally stable than the tetraradial symmetry of Quadrapyrgites; (c) different orientations of Hexaconularia, relative to the water flow, resulted in different force distributions on the surface. This research provides quantitative data of the hydrodynamic conditions of SSFs in shelf environments and critical insights into the biotic replacement of the early Cambrian benthic medusozoan community.

Effects of dietary fossil shell flour supplementation on a basal diet, relative feed values, in vitro true digestibility, and rumen fermentation parameters of Dohne-Merino wethers

ABSTRACT The availability of fossil shell flour(FSF) has increased its use as a natural feed additive in livestock diets. Therefore, identifying its optimum inclusion levels in livestock production is essential for animal productivity. This study investigated the effects of various fossil shell flour (FSF) inclusion levels on in vitro digestibility, relative feed values and rumen parameters of Dohne-Merino wethers. Twenty-four fistulated wethers, averagely 20 ± 1·5 kg body weight, were used in a complete randomized design. They were fed a basal diet without fossil shell flour (control, 0%) or with the addition of 2% FSF (T2), 4% FSF(T3) and 6% FSF (T4) of diet DM for 35 days. The results showed that increasing FSF levels had no effect on ruminal T0C or pH, but Ammonia-N increased (P < 0.01) with increasing FSF. The total molar concentrations of volatile fatty acids (VFA) decreased (P < 0.05) with increasing levels of FSF. IVTDDM, IVTDNDF and IVTDADF decreased to 4% FSF inclusion but tended to increase (P = 0.06) at 6% inclusion. Relative feed values of the diets tended to increase (P = 0.07) by adding fossil shell flour. In conclusion, adding FSF to the sheep diet had no adverse effects on the rumen parameters, though in vitro true digestibility could be reduced.

Environmental reconstructions based on aquatic and terrestrial snails originating from the Early Bronze Age and the Late Islamic Period– A stable isotope case study from the Al-Khashbah archaeological Site, Sultanate of Oman

Fossil shells of terrestrial and aquatic snails provide important information for the reconstruction of the Early Bronze Age environmental conditions in the Sultanate of Oman. Terrestrial species can be used to reconstruct available and thus consumed vegetation and the origin of precipitation, while aquatic species are useful for temperature estimates. The aim of this study is to identify past environmental conditions by generating high-resolution stable isotope series from well-preserved aragonitic shells of gastropods. A total of seven shells of the terrestrial species Zootecus insularis and five aquatic snails, Melanoides tuberculata, from Al-Khashbah were sampled. Eight of them were dated to the Early Bronze Age and four belong to the Late Islamic period that can be used as a reference. Stable isotope data of carbon (δ13Cshell) of the terrestrial snails indicate a change in digested vegetation from C3 plants in the Early Bronze Age to C4 plants in the Late Islamic period. δ18Oshell data obtained by the fully aquatic snails (range of max. 1 ‰) suggests a habitat, e.g., groundwater, with a strong environmental buffering effect. Though sudden rainfall events followed by subsequent evaporation are not recorded in the isotope record, data suggest highly variable palaeoprecipitation regimes with different origins (Indian Ocean and Mediterranean).

Vibrational spectroscopy, X-ray diffraction and EDS applied to reveal the fossilization pathways of fossil shells from the Jandaíra Formation, Upper Cretaceous Northeast Brazil

The Jandaíra Formation, Potiguar Basin, is well known for hosting a rich marine fauna from the Late Cretaceous of Brazil. Among the organisms that compose this diverse fossiliferous assemblage, the gastropods stand out for their abundance of individuals. In this study, four samples of Tylostoma sp (LP/UFC CRT 2868, LP/UFC CRT 2869, LP/UFC CRT 2870 and LP/UFC CRT 2871) were analyzed in order to understand the different diagenetic processes involved in their preservation. The fossil specimens were collected near Mossoró, state of Rio Grande do Norte. In this work, we have combined a set of high-resolution techniques such as Raman spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Scanning Electron Microscopy (SEM) and energy dispersive spectroscopy (EDS) to characterize the fossil specimens mineralogically. All fossil shells are preserved as internal molds, meaning they have lost their original organic matter. After the decomposition of organic debris, the inner part of the shell is filled with surrounding sediment. Our results revealed dolomite as the dominant phase in host rock. On the contrary, the fossil samples LP/UFC CRT 2868, LP/UFC CRT 2869, LP/UFC CRT 2870 and LP/UFC CRT 2871 showed calcite as the dominant phase. These data indicate that a similar diagenetic process was involved in the preservation of these fossil shells. Here, we document discoveries and new perspectives for looking at the abundance of fossil shells in the Jandaíra Formation.

Occurrence mode of Holocene tsunami overwash controlled by the geomorphic development along the eastern Nankai Trough, central Japan

Re-analysis of the lithological, paleontological, and geochemical data of three lagoonal sediment cores reveal the tsunami overwash history from 8000 to 6500 cal BP along the northern Suruga Bay coast, facing the eastern Nankai Trough. The coring sites are located in a transcect 0.8, 1.5, and 1.7 km inland, respectively, from the coastline at the time the overwash events occurred. The washover sand beds are distinguished from the lagoonal muds by the presence of quartz and mica, which are abundant on the outer (marine) side of the lagoon, as well as marine shell fossils. The increased C/S ratio often associated with sand beds, reflects input of open seawater to the reductive lagoon, and supports this interpretation. A maximum of eight tsunami deposits were identified between ∼7800 and 6500 cal BP, many of which can be correlated between the three cores. The magnitude of tsunami overwash implied by the thickness and grain size of tsunami deposits, and increase of C/S ratio following their deposition is relatively large at ∼7500-7200 cal BP during the post-glacial sea level rise and decreases with time during the subsequent high sea level stand. This occurrence mode (timing and scale of formation) of tsunami washover is explained by temporal changes in coastal geomorphology, rather than differences in the magnitude of individual tsunamis. Around 7500-7200 cal BP, sea level rise equilibrated with or exceeded the growth of the bay mouth barrier, and tsunamis could easily cross the small barrier and enter the lagoon, leaving behind thick and coarse-grained deposits. As the barrier becomes larger during the subsequent sea-level highstand, only the highest-amplitude waves exceeded the height of the barrier. By ∼6500 years ago, the barrier was high enough to prevent tsunamis from entering the lagoon. Similarly, the occurrence mode of tsunami deposits reported along the coast of Suruga Bay and Enshu-nada over the past 6000 years can be explained in relation to the growth of coastal barriers.

Genesis of Silica‐phosphatic Nodules with Small Shelly Fossils Preserved in the Lowermost Cambrian of South China

AbstractSilica‐phosphatic nodules are abundant in black shales of the Yanjiahe Formation in the Three Gorges Area of South China, which is correlated to the Fortunian Stage, Terreneuvian Series, Cambrian System. The nodules are rich in small shelly fossils and hence attract the attention of numerous paleontologists and sedimentary geologists. However, the genesis of the nodules and the preservation of the small shelly fossils are poorly understood. Here we analyze morphological, structural, mineralogical and chemical features of the nodules in multiscale using a combination of micro‐X‐ray fluorescence spectroscopy, X‐ray diffraction, scanning electron microscopy and confocal laser Raman spectroscopy. Results reveal that nodules are concentric in chemical and mineralogical compositions, comprising a silica‐phosphatic core encrusted sequentially by a phosphatic zone, a siliceous zone and a very thin pyrite outer rim. The black shales hosting the nodules demonstrate a laminated texture of alternating clayey and silty laminae, which were respectively deposited in sulfidic/less sulfidic, high/low production, intense/weak chemical weathering conditions. The phosphogenesis of the nodules resulted in the phosphatization of small shelly fossils, which prevented the fossils from being dissolved during diagenesis, whereas the silica encrustation sealed the fossils within the nodules and thus protected the fossils from alteration by deep burial and surface weathering.

Biostratigraphy of the Small Shelly Fossils From the Upper Maidiping Formation (Terreneuvian) at the Fandian Section, Sichuan Province, South China

Small shelly fossils (SSFs) are a useful and critical tool for subdivision and correlation of the Cambrian Terreneuvian stratigraphy. The Maidiping Formation in southern Sichuan is a well-known Terreneuvian lithologic unit with rich SSFs. Here, the upper Maidiping Formation at the Fandian section, an important supplementary section of the classic Maidiping section, is studied for understanding its SSF assemblages and stratigraphic implication. There are 26 genera, 24 species, and 3 undetermined species recovered from the Fandian section, andWatsonella crosbyiwas discovered from this section for the first time. Two SSF biozones of the Yangtze Platform,i.e., the possibleParagloborilus subglobosus–Purella squamulosaAssemblage Zone (? Zone II) and theW. crosbyiAssemblage Zone (Zone III), can be recognized. Comparing with the Maidiping section, the Fandian section has a relatively successive SSF biostratigraphy and carbon isotope stratigraphy in the upper Maidiping Formation. The SSF Zone II (?) and Zone III from the Fandian section can be, respectively, correlated to the same zones from the upper Maidiping Formation of the nearby Maidiping section (only Zone III), the upper Zhongyicun and Dahai members of the Zhujiaqing Formation in eastern Yunnan, the top Kuanchuanpu Formation in southern Shaanxi and northern Sichuan, and the beds 4 and 5 (or units 3 and 4) of the Yanjiahe Formation in western Hubei. The almost cosmopolitan distribution and nearly synchronous earliest appearance ofW. crosbyistrengthen the applicability of its first appearance data (FAD) to define the base of Cambrian Stage 2 in South China (Xiaotanian) as well as in other continents. The FAD ofW. crosbyijust around the onset of the ZHUCE carbon isotope excursion at the Fandian section also further reinforces the utility of the onset of ZHUCE as an auxiliary maker for defining the base of the Xiaotanian in South China.

Constraining marine anoxia under the extremely oxygenated Permian atmosphere using uranium isotopes in calcitic brachiopods and marine carbonates

The redox chemistry change in ancient oceans has profoundly shaped the evolutionary trajectories of animals. Uranium isotopes (δ238U) in marine carbonate sediments have widely been used to place quantitative constraints on the oxygenation state of the oceans through geological history. However, syndepositional and post-depositional diagenesis impose a positive and variable δ238U offset in the carbonate sediments relative to contemporaneous seawater, leaving uncertainties on quantification of anoxic seafloor areas in the past. Studies from modern settings suggest that Low-Magnesium Calcite (LMC) in articulate brachiopod shells are diagenetic resistant materials that may faithfully record the δ238U value of ancient seawater. However, this notation has not yet been validated in geological records. Here, we test this hypothesis by analyzing paired brachiopod shells and the host carbonate rocks from several Permian stratigraphic successions in South China. Forty-nine articulate brachiopod fossil shells and twenty-six host carbonate rocks from the Early Permian to the Late Permian were investigated. We performed a rigorous screening to monitor the diagenetic process that might have influenced the δ238U of the shells using a scanning electronic microscope, cathodoluminescent microscopy, and major and trace elements. We estimate that 53% of the shells preserve the primary seawater δ238U signals. Using the screened δ238U values of shells and bulk carbonates, we suggest there were four episodes of expanding marine anoxia during the Permian that are temporally coincident with periods of volcanism. The first two oceanic anoxic events occurred at a time when atmospheric pO2 levels were predicted to be higher than today. The last two events are temporally coincident or immediately preceding the end-Guadalupian and the end-Permian mass extinctions, respectively, confirming previous suggestions that marine anoxia was a critical factor in driving marine animal extinctions.

New Data on Paleogeography of Quaternary Coast Sediments of the Rivers of the European North of Russia Using Isotope-Geochemical Methods

(1) Background: The Quaternary river bank deposits of the European North of Russia contain several mollusk fossils that can give important past-climate information which is relevant to understand the evolution of climate in the Holocene period and predict future scenarios on climate change. (2) The purpose of the research: reconstruction of the main physical and chemical parameters of the habitat of mollusks based on the determination of the species of mollusks and the study of the isotope-geochemical composition of shells and their host deposits. (3) Object of study: Quaternary deposits of coastal outcrops of the rivers of the European North of Russia: Pechora Sula, Peza, bivalve shells, and their fragments. (4) Results: The revealed macrofauna complexes represented by bivalves (Arctica islandica, Hiatella arctica, Mytilus edulis, Tridonta borealis, Mya truncata, Neptunea despecta) were determined and the variations of δ13C and δ18O (‰) isotopes in the studied fossil bivalve shells were calculated. The data on the concentrations of chemical elements in fossil shells were determined and summarized. The content of elements in mollusk shells varied within the following limits: Fe 101.7−403.3 µg/g (Vastyansky Kon’, river Pechora), Mg 0.38–2.61 µg/g (Vastyansky Kon’, river Pechora), Ba 18.27–60.44 µg/g (village Oksino-River Sula), and Sr 1128.3–2275.34 µg/g (Vastyansky Kon’-village Oksino, river Pechora). The ratio between the elements varies within Ba/Sr 0.011–0.041 (village Oksino- River Sula) and Mg/Fe 0.01–0.15 (Vastyansky Kon’- village Oksino, river Pechora).

A fresh look at the Hyolithid Doliutheca from the Early Cambrian (Stage 4) Shipai Formation of the Three Gorges Area, Hubei, South China.

Simple SummaryDoliutheca orientalis is revised from the Shipai Formation (early Cambrian Stage 4) of the Three Gorges area, South China. Specimens are preserved as casts in silty mudstone and as small shelly fossils in calcareous pelites. SEM and Micro-CT analyses show that Doliutheca possessed hyolithid-like skeletons (especially regarding the operculum) but significantly lack helens. This combination of features sees the genus placed within the Family Paramicrocornidae, a group of hyoliths closely related to hyolithids. Newly compressed specimens of Doliutheca from silty mudstone show some soft-part preservation with the gut clearly visible. Additionally, the highly variable apex morphology of Doliutheca is explained as a consequence of differences in preservation due to secondary deposits formed inside the shell. This finding highlights the challenge of preservational artefacts in calculating the disparity and diversity of early Cambrian skeletal fossils, and the resulting potential effects on taxonomic assessments on the diversity of skeletal taxa in the Cambrian.New hyolith specimens from the early Cambrian (Stage 4) of the Three Gorges area, western Hubei Province are described and assigned to the species Doliutheca orientalis. Doliutheca are preserved in two taphonomic modes: casts in silty mudstone revealing gross morphology and some soft parts, and internal molds in calcareous pelites, which exhibit new morphological details of the conch and operculum. SEM and Micro-CT analyses show that Doliutheca preserve well-developed platy clavicles and cardinal processes on the interior of the operculum composed of rod-shaped tubular elements. This observation and the distinct cardinal and conical shields of the operculum indicate that Doliutheca could be placed within the Family Paramicrocornidae, most recently established as a group of hyoliths closely related to hyolithids.

Cantera Gorria and Red Ereño: Natural and Cultural Geoheritage (Basque Country, Spain)

Construction and ornamental stones are important elements of cultural heritage and geoheritage. The quarries, where these materials are extracted, are a type of site that combines these two types of heritage. Both the ornamental character of the rock and its place of origin can be deeply rooted in the local society. Red Ereño is a red micritic limestone (Lower Cretaceous) with abundant white rudist fossil shells. This stone has been exploited since Roman times in the north of the Iberian Peninsula (Basque Country, Spain) and exported internationally. The main quarry related to the extraction of Red Ereño, Cantera Gorria, is currently a cultural and geoheritage site. This emblematic site brings together numerous geologic (palaeontological, petrological, geomorphological and tectonic) and mining features that make it a reference point for both research and teaching activities. The link between geoheritage and cultural heritage that exists in Cantera Gorria is evident and makes this place an essential point for dissemination of geology as well as for tourism. The quarry is currently abandoned, and because of this, there is an urgent need for its protection and development, and in order to increase awareness of its importance and potential use.

Taxonomy and taphonomy of Pliocene bulimoid land snails from Māngere, northern New Zealand, with descriptions of a new genus and two new species (Gastropoda: Bothriembryontidae: Placostylinae)

ABSTRACT Two species of bulimoid land snails, Maoristylus pliocenicus n. sp. and Archaeostylus n. gen. manukauensis n. sp., in family Bothriembryontidae, subfamily Placostylinae, are described here from fossil shells that were recovered from subsurface Kaawa Formation shelly sediments at Māngere, northern New Zealand. These fossils are of late Pliocene age (Waipipian Stage [latest Zanclean-early Piacenzian], 3.7–3.0 Ma), and are the oldest known representatives of the Placostylinae. The associated fossil fauna indicates that the land snail shells were deposited at shallow subtidal depths in a coastal inlet. The teleoconch of Maoristylus pliocenicus n. sp. has highly distinctive rugose sculpture and in this regard is very similar to modern M. etheridgei (Hedley, 1891) from Lord Howe Island. The latter taxon was described as a subspecies of M. bivaricosus (Gaskoin, 1855), but it is here treated as a separate species on account of its distinctive shell morphology. Archaeostylus n. gen. manukauensis n. sp. has apertural morphology that differs markedly from other taxa in Placostylinae. Rather than being ancestral to extant taxa it probably belonged to a sister lineage. Both it and the M. pliocenicus n. sp. lineage went extinct in New Zealand during latest Pliocene or Pleistocene time, possibly as a consequence of a cooling climate.