The earliest known Cyrtina in the Prague Basin has been discovered in the Kotýs Limestone of the Lochkov Formation (Lochkovian) among a rich brachiopod-coral fauna at Branžovy ridge near Bubovice ...(Beroun District, Czechia). Rare and imperfectly preserved silicified shells are assigned to Cyrtina praecedens Kozłovski, 1929, a species originally described from Podolia, Ukraine. The species is known also in north-eastern Russia (Tajmyr and Sette-Daban Mts) and likely also in New South Wales, Australia. Its distribution provides evidence of the rapid spread of Cyrtina across the shallow shelves of Laurussia, Siberia and Gondwana in the Early Devonian. The Devonian and Carboniferous distribution of Cyrtina is restricted to the agitated, shallow-water carbonate environment in tropical and temperate climatic belts.
During the Early Jurassic, the shallow marine carbonate platforms of the western-Tethys margins were characterized by highly diverse benthos including larger foraminifera, sponges, bivalves, ...gastropods, brachiopods, echinoderms, and dasycladalean calcareous algae. In this paper, we document examples of such assemblages within the lower Pliensbachian part of the Rotzo Formation (upper Orbitopsella Zone) of the Southern Alps, Italy. This carbonate succession was deposited in a complex mosaic of marine and brackish habitats within a tropical lagoon of the Trento Platform area. Large terebratulide brachiopod shells form autochthonous accumulations comprising exceptionally well-preserved monospecific assemblages of Lychnothyris rotzoana. These brachiopod-bearing successions were analysed in terms of biotic components, microfacies analysis, shell biofabric (three-dimensional arrangement of skeletal elements), and taphonomic signatures to understand brachiopod response to changing conditions within a highly variable lagoonal palaeoecosystem. Findings show that terebratulide shell accumulations are dominated by adult specimens and juveniles are rare. The brachiopods thrived during low energy conditions that resulted in the accumulation of highly temporally-condensed shell beds. Stabilized by microbialite encrustations, the shells were not re-oriented during the subsequent rapid burial. The abrupt demise of these communities was possibly related to rapid environmental change, and causal factors are discussed. The medium-term response of brachiopods to the relatively instable ecosystem of the tropical lagoon shows that they were not able to adapt to continuous perturbations, and that continuing stress severely compromised the resilience of benthic taxa.
•Large terebratulide brachiopods thrived in Pliensbachian lagoonal settings.•Autochthonous accumulations with abundant adults and rare juveniles.•Accumulations grew under low sedimentation rate and low hydrodynamic energy.•Stabilized by microbialites shells underwent to rapid burial and early lithification.•Unpredictable environmental changes brought about the demise of the community.
Systematic study of a brachiopod assemblage from the Upper Mississippian Tonka Formation in Carlin Canyon, Elko, Nevada, USA, led to the recognition of 13 species, representing 12 genera and seven ...orders: ?Antiquatonia sp., Flexaria sp., ?Marginatia sp., Echinoconchus sp. of the Productida, ?Orthotetes sp. of the Orthotetida, Rhipidomella sp., Schizophoria sp. of the Orthida, Cleiothyridina cf. sublamellosaHall, 1858, Composita sulcataWeller, 1914 of the Athyridida, Anthracospirifer shawi shawiGordon, 1975, Anthracospirifer aff. A. shawi of the Spiriferida, Punctospirifer sp. of the Spiriferinida, and Girtyella indianensisGirty, 1909 of the Terebratulida, with the addition of one undetermined linoproductid and one genus and possibly two undetermined species of the Delthyridina. The assemblage shares affinities with upper Chesterian (middle Serpukhovian) Carlinia phillipsi and C. amsdeniana associations from western North American units, though the presence of Composita sulcata makes it also close to uppermost Chesterian faunas (Rhipidomella nevadensis and Composita popsiensis zones, upper Serpukhovian). The recorded faunal association, in terms of composition at the genus-level, is characteristic of brachiopod Unit 16 of Carter (1990a). Unit 16 spans the middle Chesterian (Gnathodus bilineatus conodont Zone) to upper Chesterian (Rachistognathus muricatus conodont Zone), corresponding to the upper Visean–Serpukhovian interval. A monospecific Vogegnathus postcampbelli conodont assemblage from the same locality confirms a late Chesterian (Serpukhovian) age of the fauna.
An accurate knowledge of the species diversity from deep-sea ecosystems is an imperative requirement in order to protect these environments in the context of global change and the biodiversity loss. ...We have examined the Brachiopoda samples collected during the COCACE (1987–88) and BIOCANT (2012–13) oceanographic cruises, from the central Cantabrian Sea and the Avilés Canyons System (ACS). The ACS is included in the Natura 2000 as a Site of Community Importance. Brachiopod specimens were collected from the continental shelf, slope and bathyal zones, ranging in deep from 117 to 4700 m. Nine hundred and thirty specimens belonging to 15 taxa (12 species and three subspecific varieties), in 12 families, were recognized. The species Dyscolia subquadrata is reported for the first time in the study area, constituting a new record from the Cantabrian Sea. We provide brief notes about the ecology and distribution of the collected species from the study area. Furthermore, we trace the biogeographical history of the involved species and review their main substrate and bio-depth zone preferences.
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•Fifteen brachiopod taxa were found in the Cantabrian Sea between 117 and 4700 m depth.•Depth was the main structuring agent that influenced the distribution of the recorded species.•Dallinaseptigera was the commonest species and Dyscolia subquadrata constitute a new record from the studied area.
We present the first Sr-isotope data on benthic, semi-pelagic and pelagic invertebrates from 10 biostratigraphical zones of Lower Cretaceous deposits in the Caucasus. We provide a 87Sr/86Sr record ...for the Lower Cretaceous of the Caucasus that represents a first step towards refining the sequence of palaeoenvironmental events in the late Barremian–early Albian interval in this region. Integration of data from the Caucasus and Middle Volga regions reveals two local minima events in the Sr-isotope record for the Aptian-lower Albian interval. The first decrease in 87Sr/86Sr to 0.70733–0.70738 (the early Aptian event) was recognized from limited material from the Volgensis-Schilovkensis Zone in the Ulyanovsk Middle Volga region. A second decrease in 87Sr/86Sr (the late Aptian event), was more pronounced than the first, and occurred within the Abichi, Nolani and Jacobi zones in the Caucasus, where the 87Sr/86Sr ratio fell to 0.70720–0.70723, 0.70720–0.70723 and 0.70721, respectively. The combined 87Sr/86Sr, δ18O, δ13C and redox records of the Caucasus, Ulyanovsk Middle Volga region and western Europe suggest that the 87Sr/86Sr decreases in the early and late Aptian times were initiated by sea-floor hydrothermal (basaltic volcanism) activity; associated palaeoenvironmental events include (1) an increase in temperature, (2) the development of anoxia (OAE-1a and OAE-b, respectively), (3) transgression and (4) a decrease in bio-productivity.
•The Sr-isotope results represent a first step toward refining the sequence of Cretaceous palaeoenvironmental events.•The first Sr-isotope data from the Caucasus help resolve some discrepancies in regional biostratigraphical reconstruction.•The integrated data suggest the legitimacy of raising the question of the existence of two Aptian falls in seawater 87/Sr/86Sr ratio.
The Permian Period is punctuated by Earth system changes unlike any other in geological history. The start of the Permian witnessed the termination of the Late Paleozoic Ice Age, followed by the ...climatic transition from icehouse to greenhouse conditions. The Guadalupian-Lopingian (Middle-Late Permian) was characterized by two biocrises associated to volcanisms: (i) the end-Guadalupian crisis and (ii) the end-Permian mass extinction. Seawater Sr isotope (87Sr/86Sr) records can shed light on the evolution of the Permian Earth system. The Permian 87Sr/86Sr record suffers from a number of issues including low resolution and potential diagenetic alteration. In this paper, we summarize the existing Permian 87Sr/86Sr records and focus on the current challenges. We also present a new, high-resolution Permian 87Sr/86Sr curve derived from pristine brachiopod shells based on data resulting from careful diagenetic screening. Our new record shows that the 87Sr/86Sr of seawater decreased continuously from the earliest Permian to the middle Capitanian (late Guadalupian), with the lowest ratio of 0.706832 registered in the Colania douvillei-Kahlerina pachiytheca Zone. Subsequently, 87Sr/86Sr ratios increased from the late Capitanian to the latest Permian and reached a ratio of 0.707167 just 0.8 m below the first occurrence of the Hindeodus parvus. We employed a stochastic oceanic box model to explore the potential drivers of the Permian seawater Sr isotope record. Our results support that changes in the hydrothermal input, rather than changes in continental weathering intensity, are the most likely controlling factor for the observed variations in Permian seawater 87Sr/86Sr. Therefore, we suggest that the marine hydrothermal system (and hence ocean basin dynamics and deep-sea temperatures) may have been the driver of the pronounced decreasing 87Sr/86Sr trend across the Permian.
Many workers dealing with twentieth-century palaeontology have incorrectly cited 'Macfadyen et al., 1935.' The correct citation should read as follows: Cox, LR, editor. The Mesozoic palaeontology of ...British Somaliland. Part 2. The Geology and palaeontology of British Somaliland. London: Government of the Somaliland Protectorate; p. 75-147.
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