The oldest nautiloid recorded from the Triassic Germanic Basin and the first ammonoid from the Aegean (Middle Triassic) of Poland

During the Triassic in Europe, the Germanic Basin extended from England in the west to the eastern border of Poland in the east. Although cephalopods are common in some Middle Triassic (Muschelkalk) horizons, there still persists a gap in the palaeontological record of the eastern part of the Germanic Basin, notably in the lowermost parts of the Lower Muschelkalk, spanning the latest Olenekian-Aegean interval. The present contribution attempts to fill this gap by presenting the first ammonoid (ceratitid Beneckeia sp.) and nautiloids (Germanonautilus cf. dolomiticus and G. cf. salinarius) from the Lower Gogolin Beds (Upper Silesia, Poland). These Germanonautilus are the oldest nautiloids found in the entire Germanic Basin.     

The mixosaurid ichthyosaur Contectopalatus from the Middle Triassic of the German Basin

The skull of the mixosaurid species Contectopalatus atavus (Quenstedt, 1851-52) is the most bizarre of any known ichthyosaur. It possesses a very high sagittal crest formed by the nasal, frontal and parietal bones which grows higher during ontogeny. This skull structure - found to a lesser extent in the other mixosaurid genera Mixosaurus and Phalarodon - is a synapomorphy of the family Mixosauridae. It is here interpreted as correlated with a unique arrangement of the jaw adductor musculature among tetrapods, with the internal jaw adductors extending over most of the skull roof up to the external narial opening. This reconstruction would increase the biting force considerably and the hypothesis is supported by peculiarities of the dentition and jaws of Contectopalatus. Contectopalatus probably reached a length of about 5 meters. It is therefore the largest known mixosaurid and one of the largest Triassic ichthyosaurs. The general text-book picture of mixosaurs as small, rather unspecialized, primitive ichthyosaurs is incorrect. Mixosaurs were a highly specialized, uniquely adapted and very diverse ichthyosaur family, some members of which rank among the marine top predators of their time.     

Extensive intraspecific variation in a Triassic ammonoid from Siberia

The ammonoid species Czekanowskites rieberin.sp . from the Lower Anisian of Arctic Siberia (River Olenek) shows an enormous range of intraspecific variability. The 700 investigated specimens are packed in one single concretion. They are all adult with preserved living chambers and apertural structures. Morphologically they range from keeled smooth suboxycones with narrow umbilicus, through feebly ribbed platycones with a little wider umbilicus, to subcadicones with relatively wide umbilicus and straight ribs with bullae. The morphological variation is continuous; all specimmh belong to a single genetically linked population, variants of one biospecies. This phenomenon, which is quite common in boreal Triassic ammonoid faunas, has in the past led to serious taxonomic oversplitting. It presents a serious challenge to current ideas about a close correlation between modeof life and shell morphology in arnmonoids.□ Amntonoidea, boreal Triassic, ecology. Siberia, variability .     

From near extinction to recovery: Late Triassic to Middle Jurassic ammonoid shell geometry

The Triassic–Jurassic extinction resulted in the near demise of the ammonoids. Based on a survey of ammonoid expansion rates, coiling geometry and whorl shape, we use the Raup accretionary growth model to outline a universal morphospace for planispiral shell geometry. We explore the occupation of that planispiral morphospace in terms of both breadth and density of occupation in addition to separately reviewing the occurrence of heteromorphs. Four intervals are recognized: pre‐extinction (Carnian to Rhaetian); aftermath (Hettangian); post‐extinction (Sinemurian to Aalenian) and recovery (Bajocian to Callovian). The pre‐extinction and recovery intervals show maximum disparity. The aftermath is marked by the disappearance of heteromorphs and a dramatic reduction in the range of planispiral morphologies to a core area of the morphospace. It is also characterized by an expansion into an evolute, slowly expanding part of the morphospace that was not occupied prior to the extinction and is soon abandoned during the post‐extinction interval. Aftermath and post‐extinction ammonoid data show a persistent negative correlation whereby rapid expansion rates are associated with narrow umbilical widths and often compressed whorls. The permanently occupied core area of planispiral morphospace represents generalist demersals whose shells were probably optimizing both hydrodynamic efficiency and shell stability. All other parts of the planispiral morphospace, and the pelagic modes of life the shells probably exploited, were gradually reoccupied during the post‐extinction interval. Planispiral adaptation was by diffusion away from the morphospace core rather than by radical jumps. Recovery of disparity was not achieved until some 30 Myr after the extinction event.     

A new stereospondyl from the German Middle Triassic, and the origin of the Metoposauridae

Recent finds of well-preserved temnospondyl skeletons from the Lower Keuper (Ladinian, Middle Triassic) in southern Germany are assigned to a new genus and species, Callistomordax kugleri . This taxon is characterized by the following autapomorphies: (1) wide unpaired frontal; (2) vomerine fangs greatly enlarged to occupy entire width of element; (3) intercentra elongated and massive, anterior face being convex; (4) humerus semilunar with enlarged deltopectoral crest; (5) cleithrum strongly curved and bow-shaped; (6) trunk extremely elongated to reach three times the length of the skull. Callistomordax shares with the Metoposauridae the pattern of dermal ornamentation, the proportion of both posterior skull table and snout, the position of the lacrimal, the morphology of the basicranial region, and the structure of the clavicle and interclavicle. Phylogenetic analysis suggests Callistomordax to be the sister taxon of the Metoposauridae, nested within a grade formed by various trematosaurian taxa. In this assemblage, Lyrocephaliscus and a clade formed by Almasaurus , Rileymillerus , Callistomordax , and the Metoposauridae are sister taxa. In all variants of the cladistic analysis, Callistomordax and the Metoposauridae form immediate sister groups. According to the present findings, neither plagiosaurids nor brachyopoids and rhytidosteids are closely related to this 'trematosaurian' monophylum, although these taxa share a range of homoplasies.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 79–113.     

Middle Triassic conodont apparatus architecture revealed by synchrotron X-ray microtomography

The composition of conodont apparatuses is crucial for understanding the feeding mechanisms of these early vertebrates. However, the multielement apparatus reconstructions of most species remain equivocal because they have been inferred from loose element collections, guided by knowledge from rare articulated ‘bedding plane assemblages’ and fused clusters, often from distantly related taxa. Even these natural assemblages can be difficult to interpret because the component elements can be closely juxtaposed or embedded in matrix, making it hard to discern the morphology of each element and their relative positions within the architecture of the feeding apparatus. Here we report five exceptionally preserved conodont clusters from the Middle Triassic Luoping Biota, Yunnan Province, Southwest China. These materials were scanned using synchrotron radiation X-ray tomographic microscopy (SRXTM), revealing the morphology and positional homology of the component elements in the fused clusters. We confirm that the apparatus of Nicoraella was composed of eight types of elements, comprising a total of 15 elements. SRXTM reveals the positional homologies of the component elements, viz. a single alate element is located in the S₀ position, flanked successively abaxially by pairs of breviform digyrate S₁ and S₂ elements, bipennate S₃ and S₄ elements, and a pair of inwardly curved breviform digyrate M elements. Carminate elements occupy the P₁ and P₂ positions. The apparatus of Nicoraella is among the most completely characterised of all conodonts and serves as a template for the reconstruction of gondollellids.     

Covariation of morphological characters in the Triassic ammonoid Czekanowskites rieberi

The Triassic ammonoid Czekanowskites rieberi displays a covariation of morphological charac ters, which is rather common in ammonoids. Its morphological spectrum ranges from laterally compressed, involute, weakly ribbed forms to depressed, semiinvolute, strongly ribbed forms. In order to study this covariation, fifteen axially cut specimens have been analyzed by means of image analysis, which allows us to obtain the ontogenetic record of radii, area and perimeter of the individual whorl cross-sections. A logarithmic model of growth has been applied. Our data indicate that, owing to the covariation, the radii from the origin to the venter and to the umbil ical seam of a given whorl section vary inversely in order to maintain the relative position of the center of gravity of the whorl cross-section both throughout the ontogeny of single specimens and within the population. This influences hydrostatic parameters, such as the position of the center of mass and the orientation and stability of the shell. Since the ontogenetic record of the angular length of the body chamber is not known, we have calculated those hydrostatic varia bles using two mutually exclusive assumptions: (1) the angular length of the body chamber was constant throughout ontogeny and (2) the volume of the body chamber grew monotonically with the revolution angle. Fluctuations of the three hydrostatic variables were always less important in the first assumption. In any case, the spectrum of, for example, theoretical orien tations is comparable to those observed in the species of present-day Nautilus. The range of adult body-chamber length observed in C. rieberi is much narrower than the theoretical adult body-chamber length calculated under the second assumption which indicates that a certain control over this parameter existed in the natural population, probably in order to maintain a narrow range in orientation and stability. The excess or deficit in soft-body weight was probably compensated by inverse variations in shell-wall weight. The main conclusion is that, despite the extreme morphological variability, hydrostatic and, possibly, hydrodynamic properties of the population remained within narrow limits.     

The oldest Mesozoic nearshore Zoophycos: evidence from the German Triassic

The trace fossil Zoophycos has been described from the Middle Triassic carbonates of the German Basin for the first time. It occurs in a calcilutite bed at the top of a shallowing-upward cycle (parasequence) in the transgressive systems tract of the Middle to Upper Muschelkalk sequence of Thuringia (Germany). Based on sedimentological and palaeontological features, the studied interval is interpreted as deposited in a marine nearshore environment with proximal storm deposits (tempestites). Zoophycos occurs in a very simple planar form with lobate spreiten, which were most likely produced by a worm-like animal by strip mining. The upper tier of the ichnofabric consists of Zoophycos, whereas the lower tier is occupied by cylindrical trace fossils of unknown taxonomic affiliation and with decreasing size towards the bottom. Associated trace fossils such as Rhizocorallium, Balanoglossites and Trypanites indicate a partly firm to hard substrate. No mixed layer is developed at the top of the trace fossil bearing succession. The ichnofabric together with the sedimentological features (disseminated pyrite, blue-grey colour) and palaeontological circumstances (poor benthic fauna, meiofauna with a small body size) support an interpretation of a dysaerobic environment. In the view of evolutionary change, Palaeozoic Zoophycos occurs in both deep and shallow marine deposits, whereas Mesozoic and Cenozoic Zoophycos is only common in shelfal and deeper-marine deposits. The new finding from the shallow-marine Middle Triassic represents the first reliable occurrence of Zoophycos after the end-Permian mass extinction and shows close similarities to its Palaeozoic precursors. It demonstrates that the producer survived the end-Permian mass extinction, became re-established in the nearshore realm and progressively colonized deeper-marine environments during the Mesozoic and Cenozoic.     

The biogeography of Early Triassic ammonoid faunas: Clusters, gradients, and networks

The aim of this paper is to quantitatively investigate the spatial and temporal biogeographical relationships of the recovery of ammonoid faunas after the Permian-Triassic mass extinction using three complementary numerical approaches among which is a new, non-hierarchical clustering strategy. The faunal data set consists of a taxonomically homogenised compilation of the spatial and temporal occurrences of ammonoid genera within 20 Early Triassic Tethyan and Panthalassic sites ranging from 40°S to 70°N in palaeolatitudes. In addition to hierarchical cluster analysis (hCA) and nonmetric multidimensional scaling (NMDS), we introduce a third, new non-hierarchical clustering technique allowing the visualisation of a nonmetric interassemblages similarity structure as a connected network constructed without inferring additional internal nodes. The resulting network, which we call a “Bootstrapped Spanning Network” (BSN), allows the simultaneous identification of partially or totally nested as well as gradational linear or reticulated biogeographical structures.The identified interlocalities relationships indicate that the very beginning of the Early Triassic (Griesbachian) corresponds to a very simple biogeographical context, representing a time of great cosmopolitanism for ammonoids. This context shifts rapidly to a more complex configuration indicative of a more endemic and latitudinally-restricted distribution of the ammonoids during the middle and late Early Triassic (Smithian and Spathian). From an evolutionary dynamic point of view, our results illustrate a very rapid (less than ca. 1.4 myr) Early Triassic recovery of the ammonoid faunas, in contrast to many other marine organisms. This recovery is linked with a marked increase in the overall biogeographical heterogeneity, and parallels the formation of a latitudinal gradient of taxonomic richness, which may be essentially controlled by the progressive intensification of the gradient of sea surface temperature. From a methodological point of view, we show that a BSN is a simple, intuitively legible picture of the nested as well as gradational taxonomic similarity relationships, hence providing a good synthesis (and additional insights) between hierarchical clustering and ordination in reduced space results.     

Taphonomy and palaeoecology of Late Triassic (Carnian) ammonoid concentrations from the Taurus Mountains,Turkey

The deposits of the Carnian Kas?mlar Formation within the Taurus Platform Units of south‐western Turkey represent an important archive of a Late Triassic ecosystem. New palaeontological information was obtained by analysing the Kasimlarceltites mass occurrence, located within the Kas?mlar Formation and named after the Lower Carnian (Julian) ammonoid genus Kasimlarceltites. This is the dominant taxon (> 94%) within the mass occurrence: nearly 775 million ammonoids and 50 million gastropods were extrapolated for the whole extension (at least 5 km²) of the Kasimlarceltites beds. This calculation is one of the main findings within this study, as it is the first time that such a fossil mass occurrence was quantified. Additionally, orientation measurements of the planispiral ammonoids and the helical gastropods enabled reconstructing the history of the mass occurrence and interpreting the underlying transport mechanisms. Further taphonomic aspects (e.g. biofabric, preservation, bioerosion or genetic classification) as well as comparisons with samples of the same acme zone from different localities near A?a?iyaylabel (AS IV, KA I‐II) point to a two‐phased genetic history. Accordingly, local mass mortality within the Kasimlarceltites fauna due to oxygen fluctuations or methane degassing may have initially led to a primary accumulation. These deposits were then reworked and redeposited basinward by gravity flows to create the present‐day secondary allochthonous concentrations.     

The black layer in cephalopods from the German Muschelkalk (Triassic)

Thin, dark, probably phosphatic coatings were found on the dorsum in front of and sometimes behind the aperture of 50 specimens of Paraceratites and Ceratites (Ammonoidea) belonging to 14 species and subspecies and in three specimens of Germanonautilus , all from the Middle Triassic of Germany. The proportions, occurrences, position, outline, and preservation in fossil Nautiloidea and Ammonoidea (originally organic matter) of this structure support the hypothesis that it is homologous with the black layer in Recent Nautilus and Allonautilus . It is not yet possible to test whether these cephalopods show homologous styles of the development of these structures or whether the black layer can be identified in a common ancestor. In contrast to many ammonoids, Ceratites and Paraceratites , most Palaeozoic ammonoids, and some Mesozoic ammonoids probably did not have lower mandibles that were suitable for the closure of the aperture. They probably possessed a dorsally extending mantle (supracephalic mantle fold) and a hood, as in Recent Nautilus and Allonautilus , that was attached to the black layer. This interpretation is corroborated by a similar morphology of the black layer in an adult specimen of the nautilid Cenoceras from the South German Middle Jurassic and three specimens of Germanonautilus from the South German Middle Triassic (both Nautiloidea).     

A procolophonoid reptile with temporal fenestration from the Middle Triassic of Brazil

The small tetrapod Candelaria barbouri, from the Middle Triassic of southern Brazil, is the first example of an owenettid procolophonoid outside Africa and Madagascar. Candelaria barbouri was originally described as a primitive procolophonid; however, a re-examination of the holotype, as well as new material, reveals that C. barbouri is in fact the youngest member of the Owenettidae, extending the chronological range of the group by more than 10 million years. The recognition of C. barbouri as an owenettid points to a broader diversity and distribution for owenettids than hitherto thought. In addition, C. barbouri is the first member of the Owenettidae to exhibit temporal fenestrae, a discovery that draws attention to the significance of this feature in 'anapsid' reptiles.     

A new rauisuchian archosaur from the Middle Triassic of India

Abstract:  Yarasuchus deccanensis gen. and sp. nov. is a new addition to the poorly known Middle Triassic terrestrial vertebrates. It is described on the basis of the fossil material of at least two incompletely preserved individuals and several isolated bones. It was a long-necked, gracile animal and might have had a facultatively bipedal gait . Apart from its characteristic elongate cervical vertebrae, other osteological features of Y. deccanensis resemble those of Prestosuchus, Saurosuchus, Ticinosuchus and ' Mandasuchus '. It is therefore referred to the Rauisuchian family Prestosuchidae despite the debated validity of this taxon.     

The shark fauna from the Middle Triassic (Anisian) of North-Western Nevada

The shark fauna from the Anisian of Nevada is dominated by durophagous hybodontiforms but also shows an important neoselachian component. Two new species of hybodontiform sharks, Acrodus cuneocostatus and Polyacrodus bucheri , are described in addition to a new neoselachian taxon: Mucrovenator minimus. The enameloid of the teeth of Acrodus and Polyacrodus comprises two layers, an outer compact layer and an inner bundled layer. For the typical three-layered enameloid of neoselachian teeth, we propose to replace the terms parallel-fibred enameloid and tangled-fibred enameloid by the more appropriate parallel-bundled and tangled-bundled enameloid.     

Fossil fungi with suggested affinities to the Endogonaceae from the Middle Triassic of Antarctica

Documented fossil evidence of zygomycetous fungi is rare. A conspicuous fungal fossil, Jimwhitea circumtecta gen. et sp. nov., occurs in permineralized peat from the Middle Triassic of Antarctica. The fossil is interpreted as a mantled zygosporangium that buds from a macrogametangium subtended by a sac-like macrosuspensor. The macrogametangium is united at its tip with a microgametangium which is subtended by a micro-suspensor. This configuration is strikingly similar to the zygosporangium-gametangia complexes seen in certain modern Endogonaceae. Co-occurring with J. circumtecta are isolated propagules closely resembling the zygosporangium of J. circumtecta and a portion of a sporocarp containing zygosporangia embedded in a gleba. Several of the sporangia are borne on ovoid or elongate structures, which we interpret as gametangia. These fossils offer an exceptionally detailed view of the morphology and reproductive biology of early Mesozoic zygomycetes.     

Late Early Triassic climate change: Insights from carbonate carbon isotopes,sedimentary evolution and ammonoid paleobiogeography

The late Early Triassic sedimentary–facies evolution and carbonate carbon-isotope marine record (δ¹³C_carb) of ammonoid-rich, outer platform settings show striking similarities between the South China Block (SCB) and the widely distant Northern Indian Margin (NIM). The studied sections are located within the Triassic Tethys Himalayan belt (Losar section, Himachal Pradesh, India) and the Nanpanjiang Basin in the South China Block (Jinya section, Guangxi Province), respectively. Carbon isotopes from the studied sections confirm the previously observed carbon cycle perturbations at a time of major paleoceanographic changes in the wake of the end-Permian biotic crisis. This study documents the coincidence between a sharp increase in the carbon isotope composition and the worldwide ammonoid evolutionary turnover (extinction followed by a radiation) occurring around the Smithian–Spathian boundary.Based on recent modeling studies on ammonoid paleobiogeography and taxonomic diversity, we demonstrate that the late Early Triassic (Smithian and Spathian) was a time of a major climate change. More precisely, the end Smithian climate can be characterized by a warm and equable climate underlined by a flat, pole-to-equator, sea surface temperature (SST) gradient, while the steep Spathian SST gradient suggests latitudinally differentiated climatic conditions. Moreover, sedimentary evidence suggests a transition from a humid and hot climate during the Smithian to a dryer climate from the Spathian onwards. By analogy with comparable carbon isotope perturbations in the Late Devonian, Jurassic and Cretaceous we propose that high atmospheric CO₂ levels could have been responsible for the observed carbon cycle disturbance at the Smithian–Spathian boundary. We suggest that the end Smithian ammonoid extinction has been essentially caused by a warm and equable climate related to an increased CO₂ flux possibly originating from a short eruptive event of the Siberian igneous province. This increase in atmospheric CO₂ concentrations could have additionally reduced the marine calcium carbonate oversaturation and weakened the calcification potential of marine organisms, including ammonoids, in late Smithian oceans.     

Taphonomy of dense ophiuroid accumulations from the Middle Triassic of Poland

The taphonomy of three Middle Triassic (Muschelkalk) monospecific ophiuroid taphocoenoses, comprising Aspiduriella similis (Eck), from different regions in Poland (Holy Cross Mountains, Upper Silesia and North-Sudetic Basin) has been investigated. The majority of specimens (88.5% of a total of 428 individuals) are partially disarticulated, having only proximal and median portions of their arms preserved (Taphonomic Group 2). Pristine specimens, with only faint traces of disarticulation (Taphonomic Group 1), as well as those that preserve the disc only, or which have only proximal stumps of arms preserved (Taphonomic Group 3), are much rarer (6.5% and 5%, respectively). Moreover, most specimens (76.4%) are oral side up. Only 19.2% of specimens are preserved in life position, and a small fraction (4.4%) are preserved oblique to bedding. All ophiuroids studied occur in thin, pelitic layers devoid of any trace fossils. Associated body fossils, such as bivalves, gastropods or crinoids, are very rare. Taking into account ophiuroid taphonomy, as well as sedimentological characteristics of the thin layer (burial layer), it is clear that all assemblages were transported prior to burial. The predominance of articulated skeletons indicates that the burial event (obrution event) was not only rapid, but also single – subsequent events would have destroyed the previously buried ophiuroids. Storm-related resuspension of fine-grained material from nearshore environments which covered the ophiuroids is the most likely burial agent. The fact that in all regions the ophiuroid taphofacies studied is identical suggests that the three assemblages underwent the same burial history, and that a single event might have been responsible.     Muschelkalk , ophiuroids , Poland , taphonomy , Triassic .     

High-resolution biochronology and diversity dynamics of the Early Triassic ammonoid recovery: The Smithian faunas of the Northern Indian Margin

Based on new collections of abundant and well preserved material from the Salt Range (Pakistan), Spiti (Northern India) and Tulong (South Tibet), several recent studies focused on the taxonomic revision and detailed biostratigraphy of Smithian ammonoids. In this work, biochronological data for these three well-documented basins are analyzed by means of the Unitary Associations method, resulting in a biochronological scheme of unprecedented high-resolution for the Smithian of the Northern Indian Margin (NIM). Data for each basin are first processed separately, thus yielding three local biochronological zonations. Then, the three sequences are processed together as a regional three-section data set for the construction of an inter-basin sequence at the NIM level. The latter zonation comprises 16 Unitary Associations grouped into 13 zones for the entire Smithian. Analysis of ammonoid diversity dynamics based on this new highly resolved time frame highlights (i) a marked diversification during the early Smithian, (ii) a severe extinction during the late Smithian, and (iii) an overall very high turnover throughout the Smithian. At a global spatial scale and stage resolution, the diversity of Smithian ammonoid genera appears surprisingly high, as highlighted by a previous study. It is shown that at a smaller geographic scale and with the most highly resolved time frame, Smithian ammonoids of the NIM reached their explosive diversity peak essentially through extremely high turnover rates rather than through a classic diversification process of high origination rates coupled with low extinction rates. Based on recently published U/Pb ages, regional apparent total rates of origination and extinction of more than 100 species per My can be inferred for the Smithian ammonoids of the NIM.     

A new ammonoid fauna from the Carnian (Upper Triassic) Kasimlar Formation of the Taurus Mountains (Anatolia,Turkey)

We describe a new ammonoid fauna from the Taurus Mountains of southern Turkey. The Carnian ammonoid fauna from A?a?iyaylabel is presented for the first time. Ammonoids were obtained from limestone to marl beds of an approximately 35‐m‐thick section, which presents the rare opportunity to investigate ammonoid faunas across the Lower–Upper Carnian boundary. Intense sampling near the village of A?a?iyaylabel led to the recognition of a new Lower Carnian (Julian 2) to Upper Carnian (Tuvalian 1) ammonoid fauna from the Kasimlar Formation. The genus Kasimlarceltites gen. nov. is reported for the first time from the Taurus Mountains, which represents the main faunal element and occurs as huge mass occurrence (n ? 1 million). Kasimlarceltites krystyni gen. et sp. nov., Klipsteinia disciformis sp. nov. and Anasirenites crassicrenulatus sp. nov. occur within the Lower Carnian Carbonate member (Units A–B) of the Kasimlar Formation from the Taurus Platform Units. Ammonoids described from the marls of the Tuvalian Marlstone member were deposited during a major, Tethyan‐wide climate crisis – the so‐called Carnian crisis – characterized by a demise of carbonate platforms. Based on the biostratigraphic relevance of certain ammonoid taxa described herein, the age of the analysed parts of the Kasimlar Formation is Julian 2 to Tuvalian 1. The discovery of the new ammonoid assemblages from A?a?iyaylabel substantiates the significance of Upper Triassic faunas within the Taurus Mountains and facilitates the correlation with faunal assemblages from other regions in the Tethyan Realm. The ammonoid fauna and facies indicate a general deepening from open‐platform margins, over deeper shelf settings down to an open marine‐influenced basinal environment. The tentative habitat for Kasimlarceltites gen. nov. is a shallow platform environment to upper mid‐ramp.