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Based on the fossil record, we explore the macroevolutionary relationship between species richness and gigantism in cowries (Cypraeidae), the best-studied family of gastropods, with a global diversity distribution that parallels that of tropical corals, mangroves and seagrasses. We introduce Vicetia bizzottoi sp. nov. based on a Priabonian fossil found in northeastern Italy, the largest documented cowrie found so far and the youngest of a lineage of Eocene Gisortiinae species. The Gisortiinae stratigraphic record in western Europe indicates that species selection favoured large size and armouring of the shell. Palaeoecology and per-stage species richness suggest that gigantism occurred in peripheral habitats with respect to diversity hotspots, where smaller species were favoured. The Eocene–Oligocene boundary was marked by a turnover and the Chattian global warming favoured small-sized species of derived clades. Species selection leading to gigantism is further documented in Miocene lineages of Zoila and Umbilia, in the southern hemisphere, two extant genera distributed at the periphery of modern diversity hotspots, suggesting that the negative relationship between size and diversity is a recurring pattern in the evolutionary history of cowries. This palaeontological evidence is projected onto the existing hypotheses that explain analogous biogeographic patterns in various other taxa. Likewise, body size-species richness negative relationship was possibly driven in cowries by physiological, ecological and life history constraints.

The scientific community is increasingly focused on the study of past climate analogues to better comprehend future implications of global warming on marine ecosystem and biogeochemical cycles. Through an integrated calcareous plankton and geochemical approach, we examined the Terche and Madeago (NE Italy) Tethyan sections, that encompass the hyperthermal Eocene Thermal Maximum 2 (ETM2, ~54 Ma). The ETM2 shares similarities with the current climate context such as global warming, carbon cycle perturbations, high pCO2 and ocean acidification, thus representing a key event in which investigate links between climate and biotic changes.Our planktic foraminiferal and calcareous nannofossil records show significant, though transient, changes in both the sections across this event. Our record of multiple dissolution proxies from both the sections ensures that dissolution did not affect calcareous plankton assemblages. Planktic foraminifera exhibit a marked increase in warm index surface-dweller Acarinina paralleled by a decline in abundance of the deeper-dweller chiloguembelinids and subbotinids. This implies that the ETM2 warming impacted the entire upper water column. Both chiloguembelinids and subbotinids, recognized as eutrophic and colder taxa, may have suffered, beside warming, of reduced food supply at the thermocline due to the increased surface-water remineralization of organic matter as induced by the significant warmth. Increase of Cretaceous calcareous nannofossils testifies reworking related to enhanced hydrological cycle that also generated input of nutrients from land. Surface water eutrophication during the ETM2 was inferred by rise in calcareous nannofossil eutrophic indices. This group proved to be more sensitive to the nutrient supply rather than warming. The ETM2 consequence on marine calcifiers test-size were not previously explored. We provide here new evidence of a striking test size reduction in planktic foraminiferal assemblages (up to 40%) during the ETM2 that involved both the surface and deeper-dweller taxa that is particularly marked at Madeago. Although loss of symbionts (bleaching) is known to affect test calcification, it cannot represent a likely cause in the studied case as both symbiotic and asymbiotic planktic foraminifera were affected at the same scale across the ETM2. The increased abundance of small placoliths Toweius and Ericsonia indicates that size reduction also impacted nannofossils, though to a lesser degree.We collected Hg (ppb), TOC (wt%) and Hg/TOC (ppb/wt%) data throughout our sections to test whether the reduction in size was related to environmental stressors not commonly linked to the ETM2. An increase in Hg was indeed detected in both sections at the base of the ETM2 and not corresponding to the intervals of reworking. Coeval submarine igneous events in this area might have introduced biolimiting metals thus involving the calcareous plankton productivity and possibly affecting test sizes. We hypothesize that the striking plankton dwarfism here recorded across the ETM2 is the result of the combined effect of paleoenvironmental perturbations induced by this event and increase in biolimiting metals. Our study alerts on possible consequences related to intense warming as associated to igneous events. Further data from different locations are needed to evaluate the geographic extension of impact on test-size variations in calcareous plankton assemblages.

The late Cenomanian-Turonian interval is characterized by major changes in the global carbon cycle, identified by stable carbon isotope excursions with associated climatic variations (e.g., OAE2, Late Turonian Events). These changes are linked to significant paleoceanographic modifications that impacted the biota, especially primary producers (e.g., calcareous plankton), forcing extinctions and evolutionary radiations. A reliable biostratigraphy is an essential tool to correlate both environmental and biotic changes worldwide.Calcareous nannofossils and planktic foraminifera are well recognized as useful markers for biostratigraphy and paleoecological studies. However, the Cenomanian-Turonian calcareous nannofossil biohorizons are still poorly constrained because the nannofossil assemblages suffer from marked provincialism and taxonomic uncertainty that can blur their biochronological potential.In order to improve the calcareous nannofossil biostratigraphic scheme of the late Cenomanian-Turonian interval, we present new data from the Breonio section (northeastern Italy), in the southwestern part of the Trento Plateau, and from the Quero section (northeastern Italy), located in the western Belluno Basin (central-western Tethys).The analyses of calcareous nannofossil and planktic foraminiferal assemblages were integrated with the δ13C, δ18O and CaCO3 curves. The δ13C values highlight several positive, global, stable carbon isotope shifts in both sections. The CaCO3 signal of the Quero section suggests that the isotopic signal is pristine because the CaCO3 values are not coupled with δ13C isotope shifts. On the contrary CaCO3 curve seems generally to reflect the lithological signal. On the basis of biostratigraphic data the detected positive shifts have been correlated with the late Cenomanian-Turonian events, specifically, the Oceanic Anoxic Event 2, Holywell, Round down, Pewsey, and Late Turonian Events 1, 2, 3. The stratigraphic position of biohorizons with respect to the globally recognized δ13C excursions can provide a valuable mean to evaluate their potential synchronism/diachronism.Our preliminary data show a good correspondence with the recent calcareous nannofossil-planktic foraminiferal integrated scheme (Geologic Time scale 2020; Gale et al. 2020) for the late Cenomanian-Turonian interval, although some calcareous nannofossil markers were not recorded. Interestingly, some «standard» and additional calcareous nannofossil events are promising proxies for the Late Turonian Events 1 and 2. ReferencesGale A.S., Mutterlose J. & Batenburg S. (2020). The Cretaceous Period, in Gradstein F.M. et al., eds., Geologic Time Scale 2020: Boston, Elsevier, pp. 1023-1086.

The first articulated dentition of †

The definition of the Cretaceous shark genusCretodusSokolov, 1965 is primarily based on isolated teeth. This genus includes five species. Among these,Cretodus houghtonorumShimada and Everhart, 2019 is the only species based on a partially preserved skeleton. Here, the taxonomic attribution of a virtually complete skeleton ofCretodusfrom the Turonian of northeastern Italy is discussed, together with a few specimens from the Turonian of England. One of the latter is investigated through micropaleontological analysis to determine its stratigraphic position. The material is referred toCretodus crassidens(Dixon, 1850), the diagnosis of which is emended herein. The dentition is tentatively reconstructed, exhibiting strong similarities with congeneric species, although it differs in having strong vertical folds on the main cusp labial face, a mesiodistally broad tooth aspect, weak and well-spaced ‘costulae’ at crown base, and a different dental formula in the number of parasymphyseal and lateral rows. Some tooth malformations are interpreted as feeding-related or senile characters. The Italian specimen suggests thatCretodus crassidenshad a wide and laterally expanded mouth and head, a stout body, and attained a gigantic size.Cretodus crassidenswas a moderate-speed swimming shark ecologically like the extant tiger sharkGaleocerdo cuvier(Péron and Lesueur in Lesueur, 1822). The age estimate from vertebral-band counting suggests that the Italian individual was at least 23 years old and the growth model indicates a longevity of 64 years and a maximum attainable total length of 9–11 m.Cretodus crassidensoccurs both in Boreal and Tethyan domains, implying a broad paleobiogeographic distribution and a preference toward offshore settings.

The late early Eocene to middle Eocene ~51–45 Million years ago (Ma) time interval in the middle bathyal, pelagic/hemipelagic succession of the western Tethys Possagno section in the Carcoselle quarry (Southern Alps, northeastern Italy), contains several episodes of negative carbon isotope excursions (CIEs) and concomitant dissolution of carbonates. Comparison with previously published carbon isotope records from deep-sea successions allows the identification of long-term trends and short-term events in our record, which provides a sound chemostratigraphic basis for correlation against the robust bio- and magnetostratigraphic scheme available for the studied succession and additional evidence of the global significance of the long-term trend and superposed perturbations tracked changes in δ13C values. Spectral analysis indicates that CIEs and associated lithological cycles are paced by orbital forcing, similar to what previously observed on the same interval in other deep-sea successions. The identification of astronomically forced geochemical cycles allows us to develop an orbitally tuned age model allowing to test the astrochronology of the ~56.0 Ma to ~47.5 Ma time interval.

The base of the Priabonian Stage is one of two stage boundaries in the Paleogene that remains to be formalized. The Alano section (NE Italy) was elected by consensus as a suitable candidate for the base of the Priabonian during the Priabonian Working Group meeting held in Alano di Piave in June 2012. Further detailed research on the section is now followed by a formal proposal, which identifies the base of a prominent crystal tuff layer, the Tiziano bed, at meter 63.57 of the Alano section, as a suitable candidate for the Priabonian Stage. The choice of the Tiziano bed is appropriate from the historical point of view and several bio-magnetostratigraphic events are available to approximate this chronostratigraphic boundary and guarantee a high degree of correlatability over wide geographic areas. Events which approximate the base of the Priabonian Stage in the Alano section are the successive extinction of large acarininids and Morozovelloides (planktonic foraminifera), the Base of common and continuous Cribrocentrum erbae and the Top of Chiasmolithus grandis (nannofossils), as well as the Base of Subchron C17n.2n and the Base of Chron C17n (magnetostratigraphy). Cyclostratigraphic analysis of the Bartonian-Priabonian transition of the Alano section as well as radioisotopic data of the Tiziano tuff layer provide an absolute age (37.710 – 37.762 Ma, respectively) of this bed and, consequently, of the base of the Priabonian Stage.

The Varignano section (Trento province, northern Italy) provides an exceptional opportunity for a direct correlation between shallow benthic (SB) zones and standard calcareous plankton zones at the Bartonian–Priabonian transition (middle–late Eocene). This transition has attracted great attention by biostratigraphers in the last decades in searching for a boundary stratotype section. The Alano di Piave section (NE Italy) is the leading candidate for the base Priabonian Global Stratotype Section and Point (GSSP). However, at Alano, larger foraminifera-bearing resedimented levels occur exclusively well below the critical interval. Conversely, the Varignano section, located ∼80 km west of the Alano section, preserves several coarse bioclastic levels rich in larger foraminifera throughout the section. These levels are intercalated with basinal marlstones, crystal tuff layers, and an organic-rich interval. The Varignano section spans planktic foraminiferal Zones E10 and E11 to lower E14, calcareous nannofossil Zones MNP16Bc to MNP18 and Chrons 18n to 17n.2n. The main calcareous plankton events recently proposed as primary base-Priabonian correlation tools, i.e., the last occurrence of the genus Morozovelloides and the Base common (= acme beginning) of Cribrocentrum erbae occur, respectively, within C17n.3n and C17n.2n. We correlate prominent crystal tuff layers exposed at Varignano with those outcropping at Alano, including the Tiziano bed, whose base has also been proposed as the GSSP level. The Varignano section spans the upper SB17 and the lower SB18 Zones, with the zonal boundary marked by the first occurrence of the genus Pellatispira. This event occurs in the lower part of Zones E13 and MNP17A within C18n, well below all the potential criteria to identify the GSSP that also includes Chron C17n.1n base. We point out that the usage of shallow-water biostratigraphers in placing the base of the Priabonian at the base of Zone SB19 is inconsistent with the proposed plankton events.

Dental and skeletal remains of Ptychodus mediterraneus from the Upper Cretaceous Scaglia Rossa Formation of northeastern Italy are described and discussed herein, together with isolated teeth of P. latissimus and P. polygyrus from the English Chalk of Sussex, southern England. The redescription of the holotype of Ptychodus mediterraneus and lectotype fixations for P. latissimus and P. polygyrus allow the systematic reassessment of the three low-crowned Ptychodus species. In addition, these taxa are compared with other morphologically similar species, such as P. martini and P. marginalis. Micropalaeontological analyses suggest a Turonian age for the low-crowned P. mediterraneus. Based on articulated tooth sets of P. mediterraneus, the pavement-like dentitions of this durophagous taxon are reconstructed herein, revealing a marked dignathic heterodonty. Imbricated dentitions observed in articulated specimens of Ptychodus mediterraneus also suggest broad distributions of bite-induced load on tooth plates; the dental features of this low-crowned durophagous shark indicate a high specialization for grinding thick-shelled bivalves (e.g., inoceramids and rudists). Fragments of cranial mineralized cartilages (e.g., a ‘V-shaped’ jaw portion) of P. mediterraneus are consistent to those commonly occurring in fusiform sharks. Evidences of scavenging on Ptychodus recorded on cartilages and tooth-bioerosion are also reported herein. Moreover, a posterior-to-anterior tooth replacement is hypothesized for Ptychodus based on the abrasion patterns observed in articulated dental sets. New insights on the palaeoecology and palaeobiology of Ptychodus are also provided.

In this paper we report for the first time remains of the long-snouted bony fish ‘Protosphyraena’ stebbingi Woodward, 1909 from the Upper Cretaceous of northeastern Italy. The material described herein consists of two rostra, one of which is nearly complete and the other only partially preserved, collected from Crespadoro (Monti Lessini) and Villa di Teolo (Colli Euganei), respectively. The overall morphology and internal structure of the rostrum of ‘P.’ stebbingi differ from those of the rostra characteristic of the genus Protosphyraena but exhibits a certain degree of similarity to those of some Cretaceous tselfatiiforms. Like in other long-snouted bony fishes, the rostrum of ‘P.’ stebbingi was probably used for prey capture and defense. The age of the Italian specimens is consistent with that of the English Chalk (Lower Chalk) where the type material of ‘Protosphyraena’ stebbingi was collected, especially the specimen from Colli Euganei, which comes from the upper Cenomanian Bonarelli Level. Taphonomic features of the specimens are also discussed, especially those of the rostrum from Crespadoro, which exhibits encrusting calcareous tubes, probably pertaining to deep-sea serpulids.

We have carried out an integrated chronostratigraphic analysis of the Alano di Piave section, proposed GSSP for the Bartonian/Priabonian boundary (late Eocene). Age constraints were derived independently from a floating cyclochronology based on carbon isotope and wt.% CaCO3 records, and 206Pb/238U dating of zircons from four volcanic tuffs. Orbital and radio-isotopic estimates of the duration of intervals bracketed by consecutive crystal-rich volcanic tuff layers are in good overall agreement, but discrepancies of 40–160 kyr are present between nominal volcanic tuff dates derived from astrochronology and 206Pb/238U. The degree to which these discrepancies are statistically significant at the 2σ level depends on the interpretation of the U-Pb zircon data, and the uncertainties assigned to the astronomical age model. The possible source and significance of these discrepancies are explored in detail. The resulting age model, combined with published bio-, and magnetostratigraphic data, is used to establish the duration of individual magnetochrons in the interval spanning the Bartonian/Priabonian transition, and the timing of late Bartonian-early Priabonian biostratigraphic and magnetostratigraphic events relative to the proposed GSSP, the regionally traceable crystal-rich tuff layer “Tiziano Bed”. The chronostratigraphic framework developed at Alano di Piave will facilitate the global correlation of the Priabonian GSSP based on both bio- and magnetostratigraphic criteria. The obtained astrochronology allows a precise correlation of the Alano di Piave δ13C record with oceanic successions confirming a strong dependency of the marine carbon cycle on astronomical forcing although with inter-site differences, which could be related to water mass organization.

In the last few years, the detailed revision of the Eocene cartilaginous fishes (Chondrichthyes) from the Bolca Lagerstätte (Italy) has provided new insights into the fish biodiversity of the western Tethys. The morphological analysis of three previously undescribed specimens from the Pesciara deposit of Bolca revealed the existence of a new stingray taxon, †Lessiniabatis aenigmatica gen. et sp. nov., which is unique among the myliobatiform batoids in having the following unique combination of characters: low number of vertebrae posterior to the pelvic girdle (65–68); thoracolumbar synarcual extending backward beyond the pelvic girdle; tail extremely short not protruding from the posterior edge of the pectoral disc; radials proximally fused to each other; pelvic girdle extremely small and strongly arched; dorsal and caudal fins absent; tail stings and cartilaginous tail rod absent; and teeth of dasyatoid morphology with smooth enameloid surface. The phylogenetic analysis suggests that †Lessiniabatis gen. nov. is deeply nested within the benthic stingrays (Dasyatoidea) representing the sister to all dasyatids and potamotrygonids. Its unique anatomy clearly reveals the existence of a new hitherto unknown body plan experimented by benthic stingrays, whose evolution can be possibly linked to the adaptive fish radiation in the aftermath of the end-Cretaceous extinction.

Dental remains of the elasmobranch Ptychodus from the Upper Cretaceous of northeastern Italy are described herein. This material, consisting of two slabs containing a partially associated tooth set and additional detached teeth with similar morphological features, derives from different lithozones of the Scaglia Rossa Formation, known as the ʻlastameʼ and ʻPietra di Castellavazzoʼ. All of these teeth are characterized by an unusual high and narrow cusp. The tooth set exhibits elements with different morphologies although they are clearly referable to a single taxon. Based on the species-specific characters of the teeth and according to the Principle of Priority of the International Code of Zoological Nomenclature, we propose herein to resurrect the species Ptychodus altior Agassiz, 1835 as a valid taxon that can easily be separated from P. rugosus Dixon, 1850. Moreover, we designate a neotype of Ptychodus altior Agassiz, 1835 since the type series seemingly is lost. Although similarly developed cusps are observed also in the species Ptychodus rugosus Dixon, 1850 and P. whipplei Marcou, 1858, the material described herein is assigned to Ptychodus altior because of the presence of a narrow cusp with smooth lateral cusp faces. The narrow high-cusped morphology characterizing this species probably indicates a different target prey compared to low-crowned congeneric species. Ptychodus altior is solely known from the Turonian-Coniacian of Europe; we review the distribution and paleobiogeography of this species, extending its range to the Angola region. The fossils described herein represent the first record of Ptychodus altior from Italy and significantly contribute to the knowledge of this species and, more generally, of the paleobiodiversity of the genus Ptychodus in the central Tethys area.

Cretoxyrhina mantelli was a large pelagic lamniform shark geographically widespread during the Late Cretaceous, and well known because of several nearly complete skeletons from the Western Interior Seaway of North America. Here we report 15 partial skeletons belonging to lamniform sharks from the ‘lastame’ lithozone of the Upper Cretaceous Scaglia Rossa Formation of the Lessini Mountains (northeastern Italy). Seven partial but articulated skeletons include tooth sets that allow a confident attribution to Cretoxyrhina mantelli based on dental morphologies. We review the taxonomic history of C. mantelli, evidencing that the taxon was erected by Agassiz (1835) and tracing back four of the original syntypes. Based on calcareous plankton biostratigraphy, the rock in which the Italian skeletal remains are embedded is constrained to the middle-upper Turonian. Total length estimates of the specimens suggest that the sample includes the largest specimen of Cretoxyrhina mantelli (615–650 cm estimated total length) known to date. The placoid scale morphology indicates that C. mantelli most likely was a fast swimmer with a similar ecology as the extant white shark, Carcharodon carcharias. The associated skeletal elements of the specimens represent large chondrichthyan deadfalls and the cadavers decayed on the seafloor where they remained exposed for several months, as indicated by bioerosional traces, some of which are interpreted as a product of bone-eating worm activities and other bioerosional traces with Gastrochaenolites-like structure. The Cretoxyrhina mantelli remains described herein provide new information about the ʻlastameʼ vertebrate assemblage, which seemingly was strongly dominated by chondrichthyans, especially lamniform sharks.

Several early Eocene hyperthermals have been recently investigated and characterized in terms of temperature anomalies and oceanographic changes. The effects of these climatic perturbations on biotic communities are much less constrained. Here we present new records from the Terche section (northeastern Italy) that, for the first time, integrates data on planktic foraminifera and calcareous nannofossils across three post Paleocene-Eocene Thermal Maximum (PETM) negative carbon isotope excursions (CIEs). The bio-magnetostratigraphic framework generated at Terche allows us to confidently relate such CIEs to the Eocene Thermal Maximum 2 (ETM2), H2, and I1 events. Each of these events coincides with lithological anomalies characterized by significantly lower calcium carbonate content (marly-units, MUs). We interpret these MUs as mainly linked to an effect of increased terrigenous dilution, as dissolution proxies do not display significant variations. Calcareous plankton assemblages change significantly across these events and radiolarians increase. Observed changes suggest that transient warming and environmental perturbations, though more intense during ETM2, occurred during each of the three investigated perturbations. Variations among calcareous plankton suggest increase in surface-water eutrophication with respect to the pre-events conditions, coupled with a weakening of the upper water-column thermal stratification. Higher nutrient discharge was related to intensification of the hydrological cycle as a consequence of the warmer climate. These conditions persisted during the early CIE recovery, implying slower recovery rates for the environment and biota than for the carbon cycle.

A marked switch in the abundance of the planktic foraminiferal genera Morozovella and Acarinina occurred at low-latitude sites near the start of the Early Eocene Climatic Optimum (EECO), a multi-million-year interval when Earth surface temperatures reached their Cenozoic maximum. Stable carbon and oxygen isotope data of bulk sediment are presented from across the EECO at two locations: Possagno in northeast Italy and Deep Sea Drilling Project (DSDP) Site 577 in the northwest Pacific. Relative abundances of planktic foraminifera are presented from these two locations, as well as from Ocean Drilling Program (ODP) Site 1051 in the northwest Atlantic. All three sections have good stratigraphic markers, and the δ13C records at each section can be correlated amongst each other and to δ13C records at other locations across the globe. These records show that a series of negative carbon isotope excursions (CIEs) occurred before, during and across the EECO, which is defined here as the interval between the J event and the base of Discoaster sublodoensis. Significant though ephemeral modifications in planktic foraminiferal assemblages coincide with some of the short-term CIEs, which were marked by increases in the relative abundance of Acarinina, similar to what happened across established hyperthermal events in Tethyan settings prior to the EECO. Most crucially, a temporal link exists between the onset of the EECO, carbon cycle changes during this time and the decline in Morozovella. Possible causes are manifold and may include temperature effects on photosymbiont-bearing planktic foraminifera and changes in ocean chemistry.

Larger agglutinated foraminifera resembling the Cretaceous genus Navarella Ciry and Rat 1951 were recently recovered in Thanetian hemipelagites from the Belluno Basin, northeastern Italy. These lituoids first appear in the basal Thanetian (uppermost calcareous nannofossils Zone CNP 8) and become common in the >500 micron washed residue from the uppermost Thanetian. They abruptly disappear at the Paleocene/Eocene boundary, in coincidence with the extinction of Paleocene small benthic foraminifera (the benthic foraminiferal extinction event - BEE). In order to document the internal chamber arrangement and the agglutinated wall microstructure of the Thanetian lituolids and to compare them with similar individuals recovered from the Upper Cretaceous and Danian strata of the same section, the collected specimens were sectioned and analyzed using a Scanning Electron Microscope (SEM), equipped with an energy-dispersive X-ray spectrometer (EDX). Our results show a typical bi-layered wall microstructure in the Thanetian specimens, whereas the older Maastrichtian and Danian specimens, occurring in the same section, display a single, thicker agglutinated wall. The taxonomy of the Italian lituolids is discussed and compared with similar taxa known from the literature. We describe the Thanetian lituolids as the new genus Neonavarella, which shows an apparently identical external morphology to mono-layered Maastrichtian-Danian specimens but differs in the microstructure of the agglutinated test wall that is bi-layered. The finding of new and well-preserved material from the Paleocene Scaglia Rossa beds of Italy helps shed light on the taxonomy of the still poorly known deep-water larger lituolids.

The middle Eocene climatic optimum (MECO, ~40 Ma) was a transient period of global warming that interrupted the secular Cenozoic cooling trend. We investigated the paleoceanographic, paleoenvironmental, and paleoecological repercussions of the MECO in the southeast Atlantic subtropical gyre (Ocean Drilling Program Site 1263). TEX86 and δ18O records support an ~4°C increase in surface and deepwater temperatures during the MECO. There is no long-term negative carbon isotope excursion (CIE) associated with the early warming, consistent with other sites, and there is no short-term negative CIE (~50 kyr) during the peak of the MECO, in contrast to what has been observed at some sites. This lack of a CIE during the peak of the MECO at Site 1263 could be due to poor sediment recovery or geographic heterogeneity of the δ13C signal. Benthic and planktic foraminiferal mass accumulation rates markedly declined during MECO, indicating a reduction of planktic foraminiferal production and export productivity. Vertical δ13C gradients do not indicate major changes in water column stratification, and there is no biomarker or micropaleontological evidence that hypoxia developed. We suggest that temperature dependency of metabolic rates could explain the observed decrease in foraminiferal productivity during warming. The kinetics of biochemical reactions increase with temperature, more so for heterotrophs than for autotrophs. Steady warming during MECO may have enhanced heterotroph (i.e., foraminiferal) metabolic rates, so that they required more nutrients. These additional nutrients were not available because of the oligotrophic conditions in the region and the lesser response of primary producers to warming. The combination of warming and heterotroph starvation altered pelagic food webs, increased water column recycling of organic carbon, and decreased the amount of organic carbon available to the benthos.

The genus Protosphyraena is known mainly from partial remains, consisting of isolated blade-like teeth, conical rostra and scythe-like pectoral fins. This paper provides a new insight into partial specimens of the genus Protosphyraena from the Cretaceous of NE Italy, housed in historical collections from local paleontological museums and previously poorly known to the international scientific community. The specimens are referred to the species Protosphyraena ferox, based on the morphology of the pectoral fin. This attribution is consistent with the paleobiogeographic distribution and stratigraphic range of this taxon. The Italian material provides new information about the distribution in time and space of Protosphyraena, which is relatively poorly known despite being an iconic taxon. The Italian remains, although fragmentary, contribute to fill a gap in the central Tethys record of the genus, whose range probably extended worldwide, considering also the genus Australopachycormus and its profound (possibly congeneric) similarities., Rivista Italiana di Paleontologia e Stratigrafia (Research In Paleontology and Stratigraphy), Vol 123, No 3 (2017)

In the nineties of the 20th century, a large and partially articulated skeleton of a lamniform shark was discovered in Upper Cretaceous hemipelagic beds of the Venetian Prealps of northeastern Italy. The shark, dating back to the middle Turonian, is here ascribed to Cretodus and represents the first record of this genus in Italy. The fossil is the most complete specimen of Cretodus so far discovered and includes 120 teeth, 86 vertebral centra and many placoid scales. Closely associated with the remains of the shark (estimated total length over 6.5 m) is a pellet-like accumulation of partially broken bones belonging to a large chelonioid turtle (about 2 m of estimated total length). Some of the bones show evidence of damages referable to bites and possible acid etching. Because of this, and because of their position in correspondence of the abdominal region of the shark, the turtle remains are interpreted as stomach content. The taphonomy of this association is discussed and compared with other fossil records of shark predation/scavenging and with lamniform shark-chelonioid turtle interactions in modern marine environment. The Italian fossil represents the second evidence of a turtle swallowed by a shark in the fossil record and a direct evidence of the possible dietary preference of Cretodus , adding some evidence for discerning scavenging from predatory lifestyle.

Sclerorhynchiform sawfishes are a diverse and extinct clade of elasmobranchs that is restricted to the Cretaceous. Most taxa are known only by isolated rostral spines, whereas skeletal remains are rare and have been reported from a small number of Upper Cretaceous localities. Here, we describe skeletal remains of the giant sclerorhynchiform Onchosaurus pharao for the first time, which provides new morphological information. The single specimen comes from middle-basal upper Turonian strata of the Lessini Mountains in northeastern Italy and represents the first record of this genus from Italy. The specimen consists of unidentifiable cranial remains, several diagnostic rostral spines, the rostrum with fragments of tessellated calcified cartilage, and 87 disarticulated vertebrae. The rostrum preserves the characteristic sensory system of sclerorhynchiforms. It is devoid of any lateral sockets indicating that rostral spines were attached laterally to its surface. This pattern is identical to most sclerorhynchiforms and extant pristiophoriformes implying also similar replacement patterns as in most other sclerorhynchiforms with the exception for Schizorhiza . Additionally, the bases of two longitudinally arranged rows of ventral rostral spines are identifiable concurring with patterns seen in Sclerorhynchus . The axial skeleton is partly preserved. Re-arranging the disarticulated vertebrae according to their life position in combination with measures of the size and thickness of preserved vertebral centra, and the ratio rostrum length/body size depending on the number of vertebral centra indicate that the specimen was ca. 450 cm long. Growth rings in the vertebral centra show that the specimen was about four years old and thus probably not yet fully sexual mature when it died. This age assumption corresponds well with the calculated size when compared with complete skeletons of extinct sclerorhynchiforms and extant pristiforms. The size of the specimen and its occurrence in hemipelagic rocks corroborates previous assumptions that this sclerorhynchiform was a large and pelagic sawfish.

The Monte Postale section (Bolca, northern Italy), one of the most famous Lagerstatten of the Eocene, has been investigated to reconstruct the sedimentary succession and to determine both the larger foraminiferal and the calcareous nannofossil biozones. The results allowed us to ascribe the Monte Postale limestones to the Shallow Benthic Zone 11 and to the calcareous nannofossil Zone CNE 5-?6 (= NP 13-?14a). The direct correlation of the SB and CNE Zones is consistent with the current biostratigraphic schemes and allows assignment of the deposition of the succession to the interval between 50.7 and 48.9 Ma, in the late Ypresian (early Eocene). According to the available biostratigraphic data, the uppermost portion of the Monte Postale section should correlate with the Pesciara limestones.

The Middle Eocene Climatic Optimum (MECO) was one of the most severe, short-term global climate perturbations of the Cenozoic that occurred at ca. 40 Ma and was characterized by a gradual 4–6 °C temperature increase of intermediate and deep-waters. We investigated the response to the MECO of the deep-sea ecosystem in the central-western Tethys, through a quantitative study of bathyal benthic foraminiferal assemblages in the expanded and continuous Alano section (northeastern Italy), for which data on stratigraphy, lithology, isotope and trace element geochemistry, and calcareous microplankton were available. During the gradual warming of MECO (lasting between 350 and 650 kyr) marine export productivity increased, causing a significant but transient restructuring of benthic foraminiferal faunas, which changed gradually from assemblages typical for oligo-mesotrophic sea floor conditions to assemblages indicative of more eutrophic conditions. Just after the peak MECO conditions, which lasted less than 100 kyr, a prolonged phase of environmental instability (~ 500 kyr) occurred, marked by even more highly increased export productivity leading to bottom-water oxygen depletion, as reflected in deposition of organic-rich sediments and multiple peaks of bi-triserial opportunistic benthic foraminiferal taxa, including buliminids, bolivinids and uvigerinids. The high productivity may have been caused by a strong influx of nutrient-bearing fresh water into the basin, due to the increased vigour of the hydrological cycle during the warm period, and this increased fresh-water influx might have been a factor in enhancing water column stratification, thus exacerbating the hypoxic conditions, which persisted about 400–500 kyr. After deposition of the organic-rich layers the environmental perturbation ended, and benthic foraminiferal assemblages recovered while conditions became very similar to what they were before the MECO. The environmental disturbance during and directly after the MECO thus strongly but transiently affected benthic foraminiferal assemblages in the central western Tethys.

The Forada section (northeastern Italy) provides a continuous, expanded deep-sea record of the Paleocene–Eocene Thermal Maximum (PETM) in the central-western Tethys. We combine a new, high-resolution, benthic foraminiferal assemblage record with published calcareous plankton, mineralogical and biomarker data to document climatic and environmental changes across the PETM, highlighting the benthic foraminiferal extinction event (BEE). The onset of the PETM, occurring ∼ 30 kyr after a precursor event, is marked by a thin, black, barren clay layer, possibly representing a brief pulse of anoxia and carbonate dissolution. The BEE occurred within the 10 cm interval including this layer. During the first 3.5 kyr of the PETM, several agglutinated recolonizing taxa show rapid species turnover, indicating a highly unstable, CaCO3-corrosive environment. Calcareous taxa reappeared after this interval, and the next ∼9 kyr were characterized by rapid alternation of peaks in abundance of various calcareous and agglutinated recolonizers. These observations suggest that synergistic stressors, including deepwater CaCO3 corrosiveness, low oxygenation, and high environmental instability caused the extinction. Combined faunal and biomarker data (BIT index, higher plant n-alkane average chain length) and the high abundance of the mineral chlorite suggest that erosion and weathering increased strongly at the onset of the PETM, due to an overall wet climate with invigorated hydrological cycle, which led to storm flood events carrying massive sediment discharge into the Belluno Basin. This interval was followed by the core of the PETM, characterized by four precessionally paced cycles in CaCO3 %, hematite %, δ13C, abundant occurrence of opportunistic benthic foraminiferal taxa, and calcareous nannofossil and planktonic foraminiferal taxa typical of high-productivity environments, radiolarians, and lower δDn-alkanes. We interpret these cycles as reflecting alternation between an overall arid climate, characterized by strong winds and intense upwelling, and an overall humid climate, with abundant rains and high sediment delivery (including refractory organic carbon) from land. Precessionally paced marl–limestone couplets occur throughout the recovery interval of the carbon isotope excursion (CIE) and up to 10 m above it, suggesting that these wet–dry cycles persisted, though at declining intensity, after the peak PETM. Enhanced climate extremes at mid-latitudes might have been a direct response to the massive CO2 input in the ocean atmosphere system at the Paleocene–Eocene transition, and may have had a primary role in restoring the Earth system to steady state.