Taxonomy and stratigraphic significance of Trachyceras silberlingi n. sp., from the Lower Carnian of South Canyon (New Pass Range, central Nevada, USA

South Canyon, localit\ue0 tipo della Zona a Desatoyense, la prima zona del Carnico nella scala cronostratigrafica nordamericana, nel 2010 e 2011 \ue8 stata oggetto di campionamenti strato-per-strato che hanno permesso di individuare una specie nuova di Trachyceras, che viene descritta in questo lavoro. La specie \ue8 dedicata a Norman J. Silberling (1928-2011) che per 50 anni \ue8 stato l\u2019autorit\ue0 indiscussa per la stratigrafia del Triassico marino nella parte occidentale degli Stati Uniti. Trachyceras silberlingi n. sp. \ue8 caratterizzato da un\u2019ornamentazione molto particolare, che consiste in due serie spirali di bullae sul fianco, una in posizione vicina al margine ombelicale e una a circa il 70% di altezza del fianco, e da coste che spesso si congiungono a coppie alla bulla laterale. La nuova specie \ue8 stata raccolta dal sito F, il sito stratigraficamente pi\uf9 alto del membro medio della Augusta Mountain Formation di South Canyon, ove rappresenta la prima sicura presenza del genere Trachyceras Laube, 1869. Per questo motivo la nuova specie T. silberlingi \ue8 estremamente utile per una prima revisione della Zona a Desatoyense, basata originariamente su raccolte di ammonoidi effettuate nella parte inferiore del membro medio della Augusta Mountain Formation, senza distinzione sui livelli di raccolta. Si propone quindi la sostituzione della Zona a Desatoyense con due unit\ue0 biostratigrafiche. I Daxatina beds sono una biozona informale caratterizzata dalla presenza di Daxatina e Frankites sutherlandi, e sono seguiti dalla biozona a Trachyceras silberlingi. Quest\u2019ultima \ue8 una zona di distribuzione formalmente istituita in questo lavoro, caratterizzata dalla presenza di Trachyceras. Viene delineato il significato cronostratigrafico delle due biozone, ma il completamento della revisione del Carnico Inferiore della scala nordamericana sar\ue0 possibile solo dopo il completamento della revisione tassonomica di tutte le faune raccolte.New intensive bed-by-bed ammonoid collecting efforts conducted in 2010 and 2011 at South Canyon, the type locality of the lowest Carnian Desatoyense Zone of the North American chronostratigraphic scale, have lead to the recognition of a new species of Trachyceras that is herein described. The new species is dedicated to Norman J. Silberling (1928-2011), who was widely recognized as the leading authority on marine Triassic stratigraphy in western US for over 50 years. T. silberlingi n. sp. is characterized by a peculiar ornamentation consisting of two spiral rows of bullae on the flank (first row on umbilical shoulder and second row at about 70% of whorl height) and by ribs frequently looped in pairs at the lateral bulla. The new species, from South Canyon site F, the stratigraphically highest level of the fossiliferous succession of the middle member of the Augusta Mountain Formation, represents the first definite occurrence of the genus Trachyceras Laube, 1869 in this succession. For this reason T. silberlingi n. sp. is of great importance for the revision of the Desatoyense Zone, a unit defined on the basis of a large collection of ammonoids described in 1941 from the lower part of the middle member of the Augusta Mountain Formation, without regard for the number and position of fossil bearing levels. We herein propose the subdivision and replacement of the former Desatoyense Zone with two biostratigraphic units: the lower unit referred to as the Daxatina beds, is an informal biozone characterized by the occurrence of Daxatina and Frankites sutherlandi, and the overlying Trachyceras silberlingi biozone is a range zone characterized by the occurrence of Trachyceras, based on the new species. The chronostratigraphic potential of this proposed subdivision is briefly outlined, but it will be more accurately defined upon completion of the taxonomic revision of the South Canyon ammonoid faunas

The Carnian/Norian boundary succession at Berlin-Ichthyosaur State Park (Upper Triassic, central Nevada, USA)

The Upper Carnian-Lower Norian (Upper Triassic) Luning Formation at Berlin-Ichthyosaur State Park (BISP) in central NV (USA) has been sampled using for the first time the bed-by-bed approach for ammonoids, pelagic bivalves, and conodonts, more than 60 years after its first description by Silberling (U.S. Geological Survey Professional Paper 322: 1\u201363, 1959). BISP is historically important for the definition of the uppermost Carnian of the North American Triassic chronostratigraphic scale and is known worldwide as one of the most important ichthyosaur Fossil-Lagerst\ue4tte because of its extraordinary record of 37 articulated, large-sized specimens of Shonisaurus popularis. Nearly 190 ammonoids were collected from two stratigraphic sections, documenting all the latest Carnian to Early Norian ammonoid faunas previously described by Silberling. Halobiids were collected from five levels, and the first report of conodonts from BISP includes faunas from 13 levels. The ~340-m thick Brick Pile section, the most complete in the study area, includes the uppermost Carnian Macrolobatus Zone, which provides conodont faunas of the lower primitia zone and Halobia septentrionalis. The 200-m thick lowermost Norian Kerri Zone, which begins 52 m above the Macrolobatus Zone, yields conodonts of the upper primitia zone in its lower part, together with H. cf. beyrichi and H. cf. selwyni. The ichthyosaur-bearing interval, whose stratigraphic position has been interpreted quite differently by previous authors, is documented in the uppermost Carnian Macrolobatus Zone and is characterized by rich Tropites-dominated ammonoid faunas and by the onset of Halobia. All models proposed by various workers to explain the unusual ichthyosaur record are discussed and an additional explanation for the main ichthyosaur-bearing bed is proposed. The new hypothesis is that a harmful algal bloom (HAB) may have been the trigger for the mass mortality recorded in this level. Although the C/N boundary in the Brick Pile section lies within a 52 m interval that presently lacks paleontologic data, this succession is included in a small group of sections that are expected to contribute to the definition of the GSSP of the Norian stage. Correlation of the Brick Pile section with the best Carnian/Norian sections in northeastern British Columbia is discussed. Compared to the British Columbia Juvavites Cove and the GSSP candidate Black Bear Ridge sections, the Brick Pile section exhibits an ammonoid and Halobia record that is slightly more similar to that of the Tethyan sections. Correlation of the Brick Pile section with the second GSSP candidate Pizzo Mondello (Sicily, Italy) well demonstrates the significant problems encountered in calibration of the Tethyan and North American scales

Anatomy of carbonate mounds from the Middle Anisian of Nakhlak (Central Iran): architecture and age of a subtidal microbial-bioclastic carbonate factory

The Anisian succession of Nakhlak (in Central Iran) is characterized by a siliciclastic succession with minor carbonate units, with massive carbonate mounds up to 50 m thick in its upper part. The mounds, constrained in age to the late Bithynian (Ismidicus Zone) by ammonoids and conodonts, are characterized by a flat top and a lateral pinch-out marked by clinostratified slopes (about 15A degrees in dip). Stratigraphic and microfacies analyses document an inner part of the mound characterized by massive microbial carbonates with open-space structures (stromatactis) filled with fine-grained internal sediments and marine cements. Isolated sponges (up to 5 cm), serpulids and bryozoans are present, which grew on the calcimicrobial limestone. A narrow bioclastic margin (mainly with crinoids and brachiopods) produces most of the slope facies (consisting of bioclastic grainstone and packstone, with intraclasts from the inner part of the mounds) which interfinger basinward with volcaniclastic sandstones. The demise of carbonate productivity is marked on the top of the carbonate mounds by a condensed surface, rich in ammonoids, glaucony grains, and articulated crinoids, documenting a rapid drowning. Paleolatitude data support deposition in a tropical setting, and sedimentological constraints indicate deposition close to the fair-weather wave base, within the photic zone. The late Bithynian Nakhlak carbonate mounds developed before the appearance (documented since the Pelsonian in different parts of the world) of scleractinians which, despite the favorable environmental conditions, are absent at Nakhlak. The Nakhlak mounds thus represent one of the last occurrences of the microbial factories (which developed after the Permo-Triassic extinction event and persisted for most of the Middle Triassic, but with a gradually increasing role played by scleractinians) before the first appearance of the Mesozoic corals

First record of Rhabdoceras suessi (Ammonoidea, Late Triassic) from the Transylvanian Triassic Series of the Eastern Carpathians (Romania) and a review of its biochronology, paleobiogeography and paleoecology

Abstract The occurrence of the heteromorphic ammonoid Rhabdoceras suessi Hauer, 1860, is recorded for the first time in the Upper Triassic limestone of the Timon-Ciungi olistolith in the Rarău Syncline, Eastern Carpathians. A single specimen of Rhabdoceras suessi co-occurs with Monotis (Monotis) salinaria that constrains its occurrence here to the Upper Norian (Sevatian 1). It is the only known heteromorphic ammonoid in the Upper Triassic of the Romanian Carpathians. Rhabdoceras suessi is a cosmopolitan species widely recorded in low and mid-paleolatitude faunas. It ranges from the Late Norian to the Rhaetian and is suitable for high-resolution worldwide correlations only when it co-occurs with shorter-ranging choristoceratids, monotid bivalves, or the hydrozoan Heterastridium. Formerly considered as the index fossil for the Upper Norian (Sevatian) Suessi Zone, by the latest 1970s this species lost its key biochronologic status among Late Triassic ammonoids, and it generated a controversy in the 1980s concerning the status of the Rhaetian stage. New stratigraphic data from North America and Europe in the subsequent decades resulted in a revised ammonoid biostratigraphy for the uppermost Triassic, the Rhaetian being reinstalled as the topmost stage in the current standard timescale of the Triassic. The geographic distribution of Rhabdoceras is compiled from published worldwide records, and its paleobiogeography and paleoecology are discussed

Association of kidney disease measures with risk of renal function worsening in patients with type 1 diabetes

Background: Albuminuria has been classically considered a marker of kidney damage progression in diabetic patients and it is routinely assessed to monitor kidney function. However, the role of a mild GFR reduction on the development of stage 653 CKD has been less explored in type 1 diabetes mellitus (T1DM) patients. Aim of the present study was to evaluate the prognostic role of kidney disease measures, namely albuminuria and reduced GFR, on the development of stage 653 CKD in a large cohort of patients affected by T1DM. Methods: A total of 4284 patients affected by T1DM followed-up at 76 diabetes centers participating to the Italian Association of Clinical Diabetologists (Associazione Medici Diabetologi, AMD) initiative constitutes the study population. Urinary albumin excretion (ACR) and estimated GFR (eGFR) were retrieved and analyzed. The incidence of stage 653 CKD (eGFR < 60 mL/min/1.73 m2) or eGFR reduction > 30% from baseline was evaluated. Results: The mean estimated GFR was 98 \ub1 17 mL/min/1.73m2 and the proportion of patients with albuminuria was 15.3% (n = 654) at baseline. About 8% (n = 337) of patients developed one of the two renal endpoints during the 4-year follow-up period. Age, albuminuria (micro or macro) and baseline eGFR < 90 ml/min/m2 were independent risk factors for stage 653 CKD and renal function worsening. When compared to patients with eGFR > 90 ml/min/1.73m2 and normoalbuminuria, those with albuminuria at baseline had a 1.69 greater risk of reaching stage 3 CKD, while patients with mild eGFR reduction (i.e. eGFR between 90 and 60 mL/min/1.73 m2) show a 3.81 greater risk that rose to 8.24 for those patients with albuminuria and mild eGFR reduction at baseline. Conclusions: Albuminuria and eGFR reduction represent independent risk factors for incident stage 653 CKD in T1DM patients. The simultaneous occurrence of reduced eGFR and albuminuria have a synergistic effect on renal function worsening

Late Ordovician Ostracoda from Iran and their significance for palaeogeographical reconstructions

The first record of Late Ordovician ostracods from Iran comes from the lowermost part of the Shirgesht Formation east of Anarak, central Iran. The fauna comprises more than 40 species of beyrichiocopes and podocopes with a total of 17 new species and one new subspecies. Among the beyrichiocopes the Binodicopa are represented with 10 species, the Palaeocopa occur with eight species. The Anarak fauna shows relations to both allochthonous and autochthonous sediments from Thuringia as well as to Baltica with the relations being closest to the fauna of certain calcareous clasts of the glaciomarine Lederschiefer of Thuringia. The clasts have been considered as pebbles or boulders from debris flows (Schallreuter & Hinz-Schallreuter 1998), but their origin remained unclear until now. Investigation of the Anarak ostracods proved to be most significant in terms of clarifying this question. The close relations between both faunas suggest that the Thuringian clasts came from the vicinity of Gondwanian Iran