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During the Middle-Late Berriasian, a long-term climatic and eustatic change occurred, documented in the literature. However, data from the northern Gondwana paleomargin are scarce. This research analyzes the Lamoricière Clay Formation at the Ouled Mimoun section, focusing on fossil assemblages and using taphonomic and ichnological aspects to interpret a transgressive-regressive cycle. The section starts with mudstones and oolitic grainstones representing shallow-water environments in the top part of the Ouled Mimoun Marly Limestones Formation (Upper Tithonian p.p. to lowermost Berriasian). The base of the Lamoricière Clay Formation is characterized by a high clay content but was still deposited in shallow water, as indicated by the record of the ostracod Asciocythere, dasyclad green algae, and the sponge Cladocoropsis. The subsequent record of fossil-rich calcareous beds at the beginning of the Upper Berriasian (Boissieri Zone) with ammonoids and calpionellids is congruent with an increase in water depth. The sedimentation rate in the Late Berriasian was reduced, as indicated by the increment of fossil remains and trace fossils. Ammonoid moulds show taphonomic features pointing to long-lasting exposure on the sea floor prior to burial with corrasion and encrustation by sessile organisms such as serpulids, thecideidinids, and bryozoans. During calm periods, crustaceans and worms intensely burrowed the sea floor. The record of Thalassinoides and Rhizocorallium indicates bottom conditions ranging from soft to firm. The low sedimentation rate and sediment by-passing probably favored early lithification. The increasing carbonate content as well as decreasing sedimentation rate is compatible with the maximum distance to emerged areas during maximum flooding. High-energy events, probably related to storms, favored the exhumation and extreme corrasion of ammonite moulds and trace fossils. In the resulting substrate, limonitic films developed and encrusting organisms proliferated (serpulids, bryozoans, and thecideidinids), colonizing both the bottom surface (hardground) and exhumed moulds of ammonoids and Thalassinoides. The uppermost 0.7 m of the section represents the return to shallow conditions, with increasing sedimentation rate and terrigenous detrital content, along with the disappearance of hemipelagic forms (ammonoids); hence it is interpreted as having developed at the beginning of a regressive context. [ABSTRACT FROM AUTHOR]

Abstract: Fossil–diagenetic features were analyzed on 56 belemnite rostra from the Pozo Cañada section (External Prebetic), as well as 31 belemnite rostra from the Río Segura (Internal Prebetic), both from the Upper Oxfordian–Lower Kimmeridgian. They mainly correspond to Hibolithes and, secondarily to Belemnopsis. Fossil–diagenetic processes were analyzed in each specimen, using petrographic (conventional, cathodoluminescence, epifluorescence and scanning electron microscopy) and geochemical (elemental and stable isotopes) techniques. The most common fossil–diagenetic processes are dissolution, calcite cementation, and recrystallization of the apical zone and outer growth rings of belemnite rostra. These processes may appear enhanced by fracturing and stylolite formation. Petrographic study also reveals that the alternation of cloudy and clear concentric growth areas displayed by many belemnite rostra corresponds to an early diagenetic feature in origin. However, an original concentric growth pattern is also observed under epifluorescent microscopy and BSEM. This growth pattern fits with changes in the Mg and S content of the rostra. Although fossil–diagenetic processes typically make specimens non-suitable for paleoenvironmental interpretations, microsampling of petrographically altered and non-altered areas from the same specimens, performed directly from thin sections after petrographic study, allowed us to obtain excellent geochemical results suitable for paleoenvironmental interpretations. These geochemical analyses moreover demonstrates that caution should be taken if elemental analyses are used as the most significant criteria for discriminating diagenetically altered and non-altered belemnite samples. [Copyright &y& Elsevier]

Abstract: A detailed taphonomic analysis was performed on 188 belemnites and 56 thin sections from the Pozo Cañada section (External Prebetic), as well as 101 belemnites and 31 thin sections from the Río Segura (Internal Prebetic), both from the Upper Oxfordian–Lower Kimmeridgian. This manuscript is focused on biostratinomic features and a second part is focused on fossildiagenetic aspects. The belemnites correspond to Hibolithes and, less commonly, Belemnopsis. Biostratinomic features, including size, fragmentation, corrasion, microboring and encrustation were analysed in each specimen, using petrographic (conventional, cathodoluminescence, epifluorescence and scanning electron microscopy) techniques. Fragmentation affects the phragmocone and the rostrum cavum, and is usually transversal and rarely longitudinal through the apical line. Isolated fragments of epirostrum are common. Corrasion produces irregular surfaces. Microborings are very common, represented by: a) Fungal hyphae; b) Fascichnus dactilus-like and Scolecia filosa-like borings (cyanobacteria); c) Entobia (sponges), d) large microborings with Y-shaped branching (diameter 100–500μm) subparallel to rostrum surface; e) large cylindrical to ellipsoidal borings related to cirripeds; and f) Palaeconchocelis starmachii (rhodophyte). Microbes and sessile foraminifera (Vinelloidea, Bullopora, Tolypammina, Thurammina, Placopsilina and Subdelloidina) are the main encrusters. Microbial films are composed of dense micrite or clotted-peloidal microfabrics. The biostratinomic features analysed in the belemnite rostra are clearly influenced by the lithofacies and shelf setting. The intensity of corrasion, microborings and encrustation, by indicating time-exposure, help establish which lithofacies shows the highest sedimentation rate. The belemnites from Internal Prebetic lithofacies—that is, the outer shelf deposits (lumpy limestone and lumpy-oncolitic limestone)—present high values of corrasion, microboring and encrustation, thereby indicating long-time exposure. In sharp contrast, belemnites from the lithofacies of the External Prebetic represent deposition in mid-shelf environments (spongiolithic limestone, spongiolithic marl–peloidal limestone, and marl–limestone rhythmite) featuring higher clay content. [Copyright &y& Elsevier]

The Middle Bathonian to Middle Oxfordian interval in the Eastern External Subbetic (Betic Cordillera, SE Spain) is characterized by Ammonitico Rosso facies including various stratigraphic breaks. Five hardground-bounded units are recognized in relation to hiatuses in the ammonite record at the following stratigraphic boundaries: Hg1 (Lower-Middle Bathonian), Hg2 (Middle-Upper Bathonian), Hg3 (Lower-Middle Callovian), Hg4 (Middle-Upper Callovian), and Hg5 (Callovian-Oxfordian). Interesting features of these hardgrounds include their microfacies, ferruginous crusts and macro-oncoids, taphonomy of macroinvertebrates, trace fossils, neptunian dykes, and the hiatuses associated with each of them. The main hardgrounds (Hg1, Hg2, and Hg5) contain trace fossils of the Cruziana and Trypanites ichnofacies as well as abundant fossil macroinvertebrates with taphonomic features evidencing corrasion, early diagenesis, and reworking, indicating substrate evolution from softground to hardground. Neptunian dykes affected the trace fossils and ammonoid moulds, and their walls and the hardground surfaces were colonized by ferruginous microbial crusts. These features are characteristic of the External Subbetic pelagic swells, where the absence of sedimentation, sediment bypassing and erosion, and early diagenesis during relative sea-level falls produced hardgrounds. The neptunian dykes are indicative of tectonic activity in the areas of pelagic swells. Ferruginous crusts and macro-oncoids developed only on hardground surfaces and neptunian dykes walls prior to deposition of condensed bioclastic beds, which are interpreted as the first deposits after hardground development and are related to the onset of transgression. The varying ranges of the gaps as well as lateral facies changes are related to different local paleobathymetry controlled by the activity of listric faults. [ABSTRACT FROM AUTHOR]

Abstract: The analysis of macroinvertebrate and foraminiferal assemblages from Upper Jurassic (Middle Oxfordian to Lower Kimmeridgian) epicontinental shelf deposits in the Prebetic (Betic Cordillera, southern Spain) reveals the influence of environmental changes. They are expressed as selected parameters in palaeogeographic and stratigraphic trends (litho- and microfacies, faunal composition, taphonomy), which are interpreted in the context of relative sea-level histories. Middle Oxfordian to early Kimmeridgian (Transversarium to Planula Chrones) rocks and faunal assemblages in comparatively distal sectors (distal shelf) show lower sedimentation rates (lumpy lithofacies), and higher proportions of ammonoids, planktic foraminifera, corrasion degree, microboring and encrustation. Landwards, towards the mid-shelf, eco-sedimentary conditions resulted in spongiolithic limestones and marl-limestone rhythmites with local development of microbial-sponge buildups. Greater distance from shore during relative sea-level highs accords with greater: (1) stratigraphic condensation; (2) abundance in ammonoids, planktic foraminifera and nubeculariids; and (3) degrees of corrasion, microboring and encrustation. These trends in faunal composition and taphonomy agree with backstepping phases, increasing ecospace and a longer exposition of shelly remains on the sea bottom. Decreasing distance from shore during relative sea-level lows relates to opposite trends, as evidenced by: (4) increasing terrigenous input and decreasing stratigraphic condensation; (5) impoverishment in ammonoids and planktic foraminifera; and (6) diminution of corrasion, microboring and encrustation. Phases of forestepping/progradation and aggradation, a reduction of ecospace for nekto-planktic organisms, and comparatively rapid burial of shell remains are interpreted to force the recorded trends. An ecostratigraphic approach is used here to correlate and characterise sea-level changes, applying high resolution stratigraphy to sections where the identification of relevant surfaces is more difficult. The changes in distance from shore and ecospace, triggered by relative sea-level fluctuations, are considered prime factors forcing trade-offs in faunal communities of the studied fossil assemblages. Ecostratigraphy was used as a template for the characterization, correlation and interpretation of relative sea-levels and associated sedimentary packages in a time span from just above the Milankovitch band to the million-year scale. [Copyright &y& Elsevier]

Abstract: Taphonomic analysis of cephalopod assemblages, together with analyses of ichnologic and sedimentologic features, are useful tools in the interpretation of the history of unconformities in Jurassic pelagic swells. The External Subbetic presents a complex evolution during the Middle Bathonian–Middle Oxfordian interval that includes hardgrounds and condensed levels rich in ammonoids. Bathonian and Callovian hardgrounds, separated by a condensed calcarenitic bed, can be differentiated. In the Bathonian hardground, ammonoids are preserved with unfilled phragmocone chambers, as a consequence of initial fast burial. Neomorphic calcite in the ammonoids is related to early diagenesis, indicating a stop in sedimentation. The ichnological features testify to an early diagenesis and progressive cementation of the sea-bottom, which is corroborated by the record of neptunian dykes. Subsequently, sediment by-passing and erosion produced reorientation of the ammonoids and belemnite remains and exhumation of moulds, during which faceting and reelaboration took place. Finally, the sedimentation began resulting in the deposition of a condensed calcarenite bed with Fe–Mn macro-oncoids. The Callovian hardground developed at the top of the calcarenite bed, where the cephalopods show signs of long exposure on the sea-bottom such as colonization by chemosynthetic microbial communities and sessile foraminifera. The study proves that the Middle Bathonian–Middle Oxfordian represents a time interval of strongly reduced and highly discontinuous sedimentation, interrupted by periods of non-deposition and erosion. [Copyright &y& Elsevier]

Abstract: Composition and taphonomy of macro-invertebrate fossil assemblages, together with facies analysis, have been approached in order to interpret shifting paleoenvironmental conditions in the External Prebetic (S-SE Spain) during the early Late Jurassic (Middle Oxfordian). In oolitic and spongiolitic limestones, the size of fossil remains, mode of preservation, within-bed position, corrasion, fragmentation, epibiont and biogenic encrustation, disarticulation and uncoupling, allow recognition of two taphofacies, respectively. Identified ecostratigraphic events and trends accord with rapid flooding under high-energy conditions related to ecospace enlargement for cephalopods and then the persistence of lower energy, long-lasting exposure of skeletals and higher sedimentary rates. The paleoenvironmental interpretation is consistent with neritic environments shifting from shallow carbonate to hemipelagic sedimentation and enlarging of shelf ecospace for marine invertebrates. [Copyright &y& Elsevier]

Microboring was investigated through thin section analysis of Oxfordian rocks from the Prebetic Zone (Betic Cordillera, southern Spain). Microboring description and distribution were analysed, as was their correlation with traits such as the type and size of bioclasts and microtaphonomic features (encrustation and fragmentation). Single and branching microboring are the two major morphological groups differentiated. Microborers were not identified but by their patterns of distribution in the bioclasts and in the environmental setting are assumed to be phototrophic. Microboring only affected bioclasts, with higher values of microboring index (MBi) registered in thicker ammonoid shells and serpulids, and lower ones in ostracods, foraminifera and small bivalves, gastropods and echinoderms. A very close, direct relationship exists between bioclast size and microboring abundance, as well as between the microboring (MBi) and encrustation indexes (Ei) used. In contrast, a clear relationship between MBi and the fragmentation index (Fi) has not been proved. Microboring activity has been interpreted to be related to both bioclast-size and time exposure of bioclasts on the seafloor, the latter resulting directly proportional to the rate of sedimentation in low energy environments. The studied features (MBi, Fi, Ei and bioclast mean size) were analysed taking into account the stratigraphic intervals investigated (I=Transversarium Zone to lower Bifurcatus Zone, II=upper Bifurcatus Zone, III=Bimammatum Zone, and IV=Planula Zone p.p.), and the trends registered were interpreted as a final consequence of relative sea-level fluctuations. Stratigraphic intervals I and IV, characterised by higher values in MBi and Ei, were related to lower sedimentary rates during increasing distality in a context of relative sea-level rise, which is consistent with the development of Transgressive System Tract (TST) conditions. Stratigraphic intervals II and III, showing lower values in MBi and Ei, are related to higher sedimentation rates and decreasing distance from shore during relative sea-level falls, which are in accordance with developing Highstand System Tract (HST) and Shelf Margin Wedge (SMW) conditions. Data obtained and interpretations agree with the general ecostratigraphic context in the studied area previously proposed by the authors. [Copyright &y& Elsevier]

The Jurassic was an important period in the evolution of Testudinata and encompasses the origin of many clades, and this is especially true of Jurassic turtles from Western Europe. A new genus and species of Late Jurassic turtle, Hispaniachelys prebetica gen. et sp. nov. from the upper Oxfordian of the Prebetic (Southern Spain), is described on the basis of postcranial material. The specimen is the only known tetrapod from the Mesozoic of the Prebetic and the oldest turtle from southern Europe. A mosaic of characters indicates this is a new genus: it displays basal features including dorsal epiplastral processes/reduced cleithra, no medial contact of the extragulars and a long first thoracic rib, alongside derived characters including an absence of mesoplastra and the vertebral 3/4 sulcus crossing neural 5. The phylogenetic position of the new taxon is hard to resolve, and it might be either a paracryptodire or a basal testudine, but it is distinct from Plesiochelys. A complex taphonomic history is shown by a range of overlying grazing traces and bioerosion on the carapace. The carapace was subsequently overturned and buried ventrally up, terminating grazing activity, and was then bored by sponges before final burial. Scanning electron microscopy reveals phosphatic microspheroids associated with bacterial decay in the vascular cavities of the cancellous bone, suggesting the carapace may have acted as a closed microenvironment in which decay-derived authigenic minerals formed. [ABSTRACT FROM AUTHOR]