Find research datasets worth reusing
Search datasets from major research repositories and use ShareScore to quickly assess how well each record supports discovery, access, and reuse.
688
datasets available to search
ShareScore release 0.9.0
Dataset results
688 results for “ammonoid”
Data from: Ontogenetic trajectories of septal spacing and shell shape in the Late Cretaceous gaudryceratid ammonoids: implications for their post-embryonic palaeoecology
Open the record for dataset details and reuse information.
Measurement data for septal spacing and conch morphology in Cretaceous ammonoids
Open the record for dataset details and reuse information.
Did shell-crushing predators drive the evolution of ammonoid septal shape?
Open the record for dataset details and reuse information.
Data from: Background extinction due to species specialization? Insights from a high-resolution Jurassic ammonoid case study (Dactylioceratidae)
Open the record for dataset details and reuse information.
Data from: The middle Smithian (Early Triassic) ammonoid Arctoceras blomstrandi: Conch morphology and ornamentation in relation to stratigraphy
<p class="MsoNoSpacing">The ammonoid genus <i>Arctoceras</i> (Hyatt, 1900) occurs across all palaeolatitudes, and is a key genus for middle Smithian (Early Triassic) biostratigraphic correlations at a global scale. In this study, intraspecific variations in conch morphology, ornamentation and allometry are examined in relation to stratigraphic position. <i>Arctoceras </i>is the most abundant ammonoid genus in the middle Smithian of Svalbard, Arctic Norway. Originally, seven <i>Arctoceras </i>species were described from Svalbard, but their practical use in fossil identification was questionable. Later, as the importance of intraspecific variation was recognized, six of the <i>Arctoceras</i> species from Svalbard were declared junior synonyms of <i>Arctoceras blomstrandi </i>(Lindström, 1865). Yet, the variations in <i>A. blomstrandi </i>conch morphology remain poorly quantified and the dependence on stratigraphic position unknown. Our research quantifies the intraspecific variation in conch morphology, ornamentation and allometry in relation to stratigraphy of the Svalbard <i>Arctoceras</i>. The results support the assignment of all <i>Arctoceras</i> morphotypes from Svalbard to a single species <i>A. blomstrandi</i>. The new data allow for an updated species description and opens for the use in biostratigraphy of the endmember morphology <i>A. blomstrandi </i>var<i> costatus</i>. We document consistent changes in both conch morphology and ornamentation in the studied stratigraphic interval with a distinct shift towards more evolute and ornate conchs in the top. The trends seen in the strength of ornamentation are partly explained by a covariation with the conch morphology, as wider and more evolute conchs tend to be more ornate (Buckman's law of covariation). The middle Smithian was characterized by a thermal maximum and low δ<sup>13</sup>C<sub>org</sub> values which shifted towards less negative values in the late Smithian and culminated in a positive carbon isotope excursion at the Smithian–Spathian boundary. The most marked shift in the conch morphology and allometric development of <i>A. blomstrandi</i> coincides with the onset of the positive carbon isotope excursion at the end of the middle Smithian, but predates the mid late Smithian cooling of the sea surface.</p>
Data from: Polymorphism in Late Cretaceous phylloceratid ammonoids: evidence from ontogenetic trajectories of septal spacing
The ontogenetic trajectories of septal spacing between succeeding chambers of two phylloceratid ammonoids, Hypophylloceras subramosum and Phyllopachyceras ezoense, from the Haboro and Kotanbetsu areas, north‐western Hokkaido, Japan, were analysed. The ontogenetic trajectories of septal spacing of H. subramosum demonstrate a general trend with large intraspecific variation: two cycles of increasing to decreasing spacing followed by almost constant spacing. The large intraspecific variation can be subdivided into three types, making this species polymorphic. The ontogenetic trajectories of septal spacing of P. ezoense also show intraspecific variation, but with a different trend: one cycle of increasing to decreasing spacing and an increasing trend after that. The intraspecific variation can be subdivided into two types, which suggests that this species is dimorphic, possibly sexually dimorphic. Dimorphism is supported by two observations: (1) the difference in the ontogenetic trajectories of septal spacing is only seen in the later ontogenetic stages; and (2) the two types co‐occur with comparable abundance throughout all stratigraphic horizons. Detailed analyses of ontogenetic trajectories of septal spacing may reveal polymorphism in other ammonoid clades.
Data from: Early evolutionary trends in ammonoid embryonic development
During the Devonian Nekton Revolution, ammonoids show a progressive coiling of their shell just like many other pelagic mollusk groups. These now extinct, externally shelled cephalopods derived from bactritoid cephalopods with a straight shell in the Early Devonian. During the Devonian, evolutionary trends toward tighter coiling and a size reduction occurred in ammonoid embryonic shells. In at least three lineages, descendants with a closed umbilicus evolved convergently from forms with an opening in the first whorl (umbilical window). Other lineages having representatives with open umbilici became extinct around important Devonian events while only those with more tightly coiled embryonic shells survived. This change was accompanied by an evolutionary trend in shape of the initial chamber, but no clear trend in its size. The fact that several ammonoid lineages independently reduced and closed the umbilical window more or less synchronously indicates that common driving factors were involved. A trend in size decrease of the embryos as well as the concurrent increase in adult size in some lineages likely reflects a fundamental change in reproductive strategies toward a higher fecundity early in the evolutionary history of ammonoids. This must have played an important role in their subsequent success as well as in their demise.
Data from: Palaeobiogeographical structuration of Smithian (Early Triassic) ammonoid faunas within the western USA basin and its controlling parameters
We present the first quantitative palaeobiogeographical analysis in terms of distribution and abundance of Early Triassic ammonoids from the western USA basin during the Smithian, c. 1 myr after the Permian–Triassic boundary mass extinction. The faunal dataset consists of a taxonomically homogenized compilation of spatial and temporal occurrences and abundances from 27 sections distributed within the western USA basin. Two complementary multivariate techniques were applied to identify the main biogeographical structuring recorded in the analysed presence/absence data: additive cluster analysis using the neighbor‐joining algorithm (NJ) and non‐metric multidimensional scaling (NMDS). Regarding abundance data, a taxonomic diversity (sensu evenness) analysis was coupled with graphical comparisons of relative abundances of selected taxa. The identified relationships indicate that middle Smithian ammonoids of the western USA basin were geographically organized in terms of both distribution and abundance, with the biogeographical distinction of a southern and a northern cluster. This N–S structuring in the distribution and abundance of middle Smithian ammonoids is notably paralleled by the relative amount of siliciclastics, which suggests that clastic load of the water column was a major controlling factor. In marked contrast with the middle Smithian, the studied late Smithian ammonoid assemblages do not show any significant differences, whatever the depositional environment. This abrupt biogeographical homogenization, independent from intrabasinal facies heterogeneity, indicates a switch from regional to global drivers, associated with the well‐known late Smithian global extinction and remarkable cosmopolitan ammonoid distributions during that time.
Data from: A new Griesbachian-Dienerian (Induan, Early Triassic) ammonoid fauna from Gujiao, South China
Bed-by-bed sampling of the lower portion of the Daye Formation at Gujiao, Guizhou Province, South China, yielded new Griesbachian–Dienerian (Induan, Early Triassic) ammonoid faunas showing a new regional Induan ammonoid succession. This biostratigraphic scheme includes in chronological order the late Griesbachian Ophiceras medium and Jieshaniceras guizhouense beds, and the middle Dienerian Ambites radiatus bed. The latter is recognized for the first time as a separate biozone in South China. Eight genera and 13 species are identified, including one new species, Mullericeras gujiaoense n. sp. The new data show that a relatively high level of ammonoid taxonomic richness occurred rather rapidly after the Permian/Triassic mass extinction in the late Griesbachian, echoing similar observations in other basins, such as in the Northern Indian Margin.
Data from: Intraspecific variability through ontogeny in early ammonoids
Mollusks in general and ammonoids in particular are known to display a sometimes profound morphological intraspecific variability of their shell. Although this phenomenon is of greatest importance, it has rarely been investigated and quantified. It is especially crucial for taxonomy and incidentally for biodiversity analyses to account for it, because otherwise, the number of described species might exceed that of actual species within any group. Early ammonoids (Early Devonian, Paleozoic) typically suffer from this bias. For instance, most specimens from the same layer and the same region (e.g., the Erbenoceras beds of the Moroccan eastern Anti-Atlas studied here) differ morphologically from each other. Depending on the importance given to certain morphological characters, therefore, one could create a new species for almost every specimen. In this study, we measured nearly 100 such specimens from a restricted stratigraphic interval and quantified their intraspecific variability. There is a variable but strong overlap of the quantified shell characters at most ontogenetic stages, and only two species are here separated rather than the four previously recognized in Morocco. When ontogenetic trajectories of the Moroccan specimens are compared with coeval faunas from other regions (assigned to other species), a strong overlap between the morphospaces occupied by these taxa becomes apparent. The justification of some of these latter species is thus questionable even if their mean values in some conch parameters differ considerably from the mean values of the Moroccan species. Hence, the number of currently valid species of these loosely coiled early ammonoids is probably much too high. Extreme caution must therefore taken when examining the diversity of groups in which the intraspecific variability is poorly known.
Data from: Different modes of migration among Late Cretaceous ammonoids in northwestern Hokkaido, Japan: evidence from the analyses of shell whorls
The thickness ratios of shell whorls (= whorl breadth / shell diameter) in the ammonoids Damesites sugata, Hypophylloceras subramosum, and Gaudryceras tenuiliratum from the Late Cretaceous outer shelf deposits in the Kotanbetsu area of northwestern Hokkaido, Japan, were examined in order to determine their mode of migration. The thickness ratios of D. sugata differ significantly with depth on the outer shelf environment, but show no significant difference laterally at a similar depth. These results suggest that D. sugata did not frequently migrate to different depths on the outer shelf environment, but tended to live and migrate laterally at a similar depth on the outer shelf. The thickness ratios of H. subramosum and G. tenuiliratum show no significant difference between different depths on the outer shelf environment nor for lateral direction at a similar depth. This suggests that H. subramosum and G. tenuiliratum frequently migrated at different depths on the out er shelf environment and laterally at a similar depth. There is no difference in hatchling diameters in all the examined species at different depths on the outer shelf environment, suggesting that the thickness ratios became manifest after the post-hatchling stage due to limited migration, which would have been in a nektobenthic habitat. The various modes of migration in the study area are reconstructed in this study, suggesting a diversified paleoecology of Late Cretaceous ammonoids.
Data from: Integrating 2D and 3D shell morphology to disentangle the palaeobiology of ammonoids: a virtual approach
Based on data derived from computed tomography, we demonstrate that integrating 2D and 3D morphological data from ammonoid shells represents an important new approach for investigating the palaeobiology of ammonoids. Characterization of ammonite morphology has long been constrained to 2D data, with only a few studies collecting ontogenetic data in 180° steps. Here we combine this traditional approach with 3D data collected from high-resolution nano-computed tomography. Ontogenetic morphological data on the hollow shell of a juvenile ammonite Kosmoceras (Jurassic, Callovian) was collected. 2D data was collected in 10° steps and show significant changes in shell morphology. Preserved hollow spines show multiple mineralized membranes never reported before, representing temporal changes in the ammonoid mantle tissue. 3D data show that chamber volumes do not always increase exponentially, as was generally assumed, but may represent a proxy for life events, such as stress phases. Furthermore, chamber volume cannot be simply derived from septal spacing in forms comparable to Kosmoceras. Vogel numbers represent a 3D parameter for chamber shape, and those for Kosmoceras are similar to other ammonoids (Arnsbergites, Amauroceras) and modern cephalopods (Nautilus, Spirula). Two methods to virtually document the suture line ontogeny, used to document phylogenetic relationships of larger taxonomic entities, were applied for the first time and present a promising alternative to hand drawings. The curvature of the chamber surfaces increases during ontogeny due to increasing strength of ornamentation and septal complexity. As this may allow for faster handling of cameral liquid, it could compensate for decreasing SA/V ratios through ontogeny.
Data from: Untangling phylogenetical, geometrical and ornamental imprints on Early Triassic ammonoid biogeography: a similarity-distance decay study.
Ammonoids are diverse and widespread fossil shelly cephalopods that flourished in the world ocean during more than 300 million years before their total extinction, 65 million years ago. In spite of two centuries of intensive scientific studies, their mode(s) of life, and most particularly long-distance dispersal abilities remain poorly known. Here we address this question by looking at the latitudinal distribution of Early Triassic (~250 Myr) ammonoids through similarity-distance decay analyses. We examine and compare how rates of similarity-distance decay differ between various systematic, shell geometry and ornamentation groups, during the same ~3.5 myr Early Triassic time interval, in order to untangle phylogenetical, geometrical and ornamental imprints on the observed biogeographical pattern. Our data do not support any phylogenetical and shell ornamentation control on the similarity-distance decay, but rather evidence a significant effect of (sub-)adult shell geometry: most evolute morphs tend to have been more endemic than most involute ones. This result contrasts with the classical hypothesis that long-distance ammonoid dispersal mainly occurred during the earliest planktonic young stages, and thus that (sub-)adult morphological characteristics should not constrain large-scale biogeographical patterns of ammonoids. While a direct control by Sea Surface Temperature can be discarded, this result may indicate that at least some adult Triassic ammonoid morphs were good active swimmers able to achieve long-distance migrations, as observed for some present-day coleoid cephalopods.
Data from: 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 Aşağiyaylabel is presented for the first time. Ammonoids were obtained from limestone to marl beds of an approximately 35-m-thick section, which depicts the scarce possibility to investigate ammonoid faunas across the Lower–Upper Carnian boundary. Intense sampling near the village of Aşağiyaylabel 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 (Unit 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 analyzed parts of the Kasimlar Formation is Julian 2 to Tuvalian 1. The discovery of the new ammonoid assemblages from Aşağiyaylabel 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.
Supplementary data and codes for ammonoids morphological complexity and evolutionary rates
<p>The "code" folder contains the code for calculating evolutionary rates and analysing the data, and the input and output data. We used the Bayesian framework implemented within the program PyRate, the per capita boundary-crosser rate, per-taxon rate, and Van Valen metric to calculate extinction and origination rates for early Pliensbachian species and Cretaceous genera datasets. The Pyrate method is implemented in python, all other methods use R code.</p> <p>The "obj" folder includes 292 three-dimensional models of 146 specimens.</p> <p>The "Expanded Data" file containing supplementary tables, original data, processed data and specimen tables.</p>
Data from: Integrating 2D and 3D shell morphology to disentangle the palaeobiology of ammonoids: a virtual approach
Open the record for dataset details and reuse information.
Data from: Anisian (Middle Triassic) ammonoids from British Columbia (Canada): biochronological and palaeobiogeographic implications
Open the record for dataset details and reuse information.
Data from: Untangling phylogenetical, geometrical and ornamental imprints on Early Triassic ammonoid biogeography: a similarity-distance decay study.
Open the record for dataset details and reuse information.
Data from: A new Griesbachian-Dienerian (Induan, Early Triassic) ammonoid fauna from Gujiao, South China
Open the record for dataset details and reuse information.
Data from: Different modes of migration among Late Cretaceous ammonoids in northwestern Hokkaido, Japan: evidence from the analyses of shell whorls
Open the record for dataset details and reuse information.
ScienceDex guides
Understand access before you commit
These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.