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Eight coleoid genera have so far been described from the Callovian‐aged La Voulte‐sur‐Rhône Lagerstätte (c. 165 Ma; Ardèche, France), a locality noted for its unique three‐dimensional preservation of soft tissues. Here, we used high resolution x‐ray‐based imaging methods, in conjunction with reflectance transformation imaging, to study the soft tissues of a previously undescribed coleoid from the La Voulte‐sur‐Rhône locality. This analysis identified both an ink sac and internal light organs, a combination of defence mechanisms present in the Recent, although not previously described from the coleoid fossil record, as well as the presence of Octobrachia‐type arm musculature and Vampyroteuthis‐like sucker attachments. The morphology of the gladius could not be attributed to any known coleoids and therefore justified the assignment of this single specimen to a new taxon: Vampyrofugiens atramentum. The addition of this new vampyromorph species not only increases the coleoid diversity known from the site, but also broadens the morphological variation observed in the co‐occurring coleoid taxa. These findings suggest that there was a high diversity of cephalopods occupying differentiated communities during the Middle Jurassic. [ABSTRACT FROM AUTHOR]

The complete ontogenetic development of an asteroid skeleton has never been described formally for any species. Here, we describe in detail the post‐metamorphic ontogeny of Zoroaster fulgens Thomson, 1873. The major novelty of our work is the description of patterns of plate addition, the ontogeny of the internal ossicles, as well as the variability of ossicles according to their position along series. Seven specimens collected in the Rockall Basin (North Atlantic) were dissected with bleach and their anatomy was documented using a scanning electron microscope. The external anatomy was additionally observed on more than 30 specimens. We found that the overall structure of the skeleton does not change much between juveniles and adults, but the shape of individual ossicle changes during growth. Allometric scaling was particularly visible on the orals, ambulacrals and adambulacrals. The shape of an ossicle is more dependent of its position along the arm series than of its individual size. Many morphological features differentiate progressively during ontogeny, while others are expressed consistently among specimens. The study of this ontogenetic series allows discussing the homology between the structures present on the ossicles of Z. fulgens in particular and other forcipulatacean sea stars in general (i.e. muscles insertions and articulation areas). The new data obtained in this study provide a comprehensive framework of the anatomy and ontogeny of Z. fulgens that will help resolve taxonomic and phylogenetic controversies in the future. [ABSTRACT FROM AUTHOR]

A mass occurrence, numbering tens of thousands of individuals in a single lens, belonging to a single species of asteroid, is described from the late Maastrichtian (Late Cetaceous) of Morocco. The lens of partially silicified asteroidal limestone is made up largely of fully articulated specimens of similar size and probably represents the mass mortality of a single recruitment. By comparison with mass strandings of the present-day species Asterias rubens (Linnaeus), it can be inferred that a feeding swarm of individuals was swept into a submarine channel by either a storm or an exceptionally strong tidal current, and permanently buried. The genus and species are herein described as Cretasterias reticulatus gen. et sp. nov. The exceptional preservation of the material enables the identification of wreath organs (clusters of crossed pedicellariae set in a dermal pad around spines) for the first time in the fossil record. Comparison between extant Asteriidae, putative fossil asteriids and C. reticulatus provides ambiguous evidence of its affinities; it appears to display a combination of plesiomorphic and derived characters. It is shown that all Mesozoic forcipulatid asteroids described so far share a very simple arm construction (single row of adradial ossicles) unknown in adult extant Forcipulatida. [ABSTRACT FROM AUTHOR]

This paper describes the evolution of an extensional basin in regard to the nature and sequence stratigraphic arrangement of its carbonate deposits. The purpose of this study is to evaluate the respective effects of tectonism, eustasy, climate and oceanography on a carbonate sedimentary record. The case study is the early to mid-Jurassic age carbonate succession of the Southern Provence Sub-basin (SE France), located within the southern part of the extensional Western European Tethyan Margin. This work is based on sedimentologic, biostratigraphic (using ammonites and brachiopods) and sequence stratigraphic analysis of the carbonate facies of the Cherty Reddish Limestone Formation (late Sinemurian to earliest Bajocian). These strata were deposited in shoreface to lower offshore depositional environments. The succession of the various environments together with the recognition of key stratigraphic surfaces allow us to define four second-order depositional sequences; of late Sinemurian to earliest Pliensbachian, early Pliensbachian to late Pliensbachian, earliest Toarcian to middle Aalenian and late Aalenian to early Bathonian ages. The architecture of the depositional sequences (thickness and facies variations within the systems tracts, wedge-shaped geometries) reflects a strong tectonic control. The sub-basin was structured by extensional faults (oriented approximately 070–090/250–270). Sea-level variations, fluctuations in carbonate production and preservation, and environmental changes were also significant controlling factors of the carbonate deposition. The interplay of the tectonic control with the other factors resulted in five main phases in the sedimentary evolution of the sub-basin: (1) dominant tectonic control during the initial rifting stage (late Sinemurian to early Pliensbachian); (2) increasing extensional tectonics (mid-Pliensbachian); (3) global climato-eustatic sea-level fall (latest Pliensbachian) and global climato-eustatic sea-level rise plus hypoxia/anoxia (early Toarcian); (4) relative sea-level fall linked to tectonic uplift related to the ‘Mid-Cimmerian phase’ (mid-Aalenian) and (5) oceanographic events (upwelling) and reduction in carbonate production (hypoxia/anoxia) plus tectonic downwarping (late Aalenian/earliest Bajocian). [ABSTRACT FROM AUTHOR]

A phylogenetic analysis of 36 species provides a test for the taxonomy and the history of Early Cretaceous spatangoids. Most taxonomic units from genera to suborders are consistent with the proposed phylogenetic framework. We retain Hemiasterina, Micrasterina, Hemiasteridae, Schizasteridae, Hemiaster, Heteraster, Mecaster, and Periaster as original monophyletic groups. However, all of these clades originate without the classical apomorphies normally ascribed to them. We suggest a revision of their diagnoses and of the generic attributions of basal species. Some ill-defined, ‘primitive’, and paraphyletic taxa are recognised: Toxaster, Epiaster, Palhemiaster, and Toxasteridae. Even if they do not have phylogenetic meaning, they are retained here, pending a more complete revision. [ABSTRACT FROM AUTHOR]