98 research outputs found

    MORPHOMETRIC APPROACH TO DETERMINATION OF LOWER JURASSIC SIPHOVALVULINID FORAMINIFERA

    Get PDF
    Siphovalvulina is among the first foraminifera that appear on carbonate platforms of the Lower Jurassic, forming a conspicuous element of low-diversity assemblages prior to recovery after the end-Triassic biotic crisis. The high morphologic variability of species of this genus is usually not documented, which makes the determination of species difficult and subjective. We demonstrate the variability in five morphotypes of Siphovalvulina in Sinemurian and Pliensbachian carbonate rocks from the Dinarides and the Southern Apennines. Due to the different interpretation of its architecture, an emendation of the genus Siphovalvulina is proposed. One morphotype has been left in open nomenclature and could belong to either S. variabilis Septfontaine or to S. beydouni BouDagher- Fadel & Noujaim Clark. Three morphotypes, differing in apical angle and/or size belong to S. ex gr. gibraltarensis BouDagher-Fadel, Rose, Bosence & Lord. We also describe a new genus and species, Radoicicina ciarapicae gen. n., n. sp. from the lower Sinemurian of the Southern Apennines. We suggest a close phylogenetic relationship between the two genera and introduce a new family, Siphovalvulinidae fam. n. of the superfamily Eggerelloidea

    Paleocene orthophragminids from the Lakadong Limestone, Mawmluh Quarry section, Meghalaya (Shillong, NE India). Implications for the regional geology and paleobiogeography

    Get PDF
    The late Paleocene orthophragminids, hitherto poorly known from the Himalayan foreland basins, are studied from the Lakadong Limestone in Meghalaya, northeastern India, in order to establish a systematic, biostratigraphic, and paleobiogeographical framework for them in the eastern Tethys. In the Mawmluh Quarry section (MQS) on the Shillong Plateau, to the southeast of Tibet, orthophragminids are associated with typical Paleocene orbitoidiform taxa endemic to the Indian subcontinent, i.e., Lakadongia Matsumaru & Jauhri ( D Setia Ferràndez-Cañadell) and Orbitosiphon Rao, and various species of alveolinids, miscellaneids, and rotaliids, characterizing the Shallow Benthic Zones (SBZ) 3 and 4. The orthophragminids belong to two lineages of the genus Orbitoclypeus Silvestri: O. schopeni (Checchia-Rispoli) and O. multiplicatus (Gümbel), both well known from the peri-Mediterranean region and Europe (western Tethys). The latter species is identified here for the first time from the eastern Tethys. Previous records of the genus Discocyclina Gümbel from the Lakadong Limestone actually correspond to misidentified Orbitoclypeus; this implies that the late Paleocene orthophragminid assemblages from Meghalaya and eastern Tethys were less diverse than in the western Tethys. The lineage of Orbitoclypeus schopeni in the lower part of the Lakadong Limestone (SBZ 3) is identified as O. schopeni cf. ramaraoi based on the morphometry of a few specimens, whereas in the upper part (SBZ 4) it corresponds to a transitional development stage between O. schopeni ramaraoi and O. schopeni neumannae (with average Dmeanvalues ranging between 192 and 199 μ m). The embryon diameters of O. multiplicatus, recorded only in SBZ 4, range between 300 and 319 μ m on average, corresponding to transitional development stages of O. multiplicatus haymanaensis and O. multiplicatus multiplicatus. Our data, along with a review of previous Paleocene and Eocene records from India and Pakistan, suggest that Orbitoclypeus is the only orthophragminid in the Paleocene of the eastern Tethys, whereas Discocyclina first appears in early Eocene times, being mainly represented by endemic taxa confined to the Indian subcontinent. Facies change in the MQS from a marine to continental setting within SBZ 4 corresponds to the oldest record from the Indian plate in the Paleogene, which may be linked to the flexural uplift of the passive margin of the Indian plate, marking the onset of the collision of the Indian and Eurasian plates

    A new polyphysacean alga from the Miocene of Romania and its biomineralization

    Get PDF
    Polyphysacean algal fertile caps from the Sarmatian near Suceava (NE Romania) are here described as a new species, Acetabularia moldavica, ascribed to the extant genus Acetabularia due to the presence of both inferior and superior coronae. Gametangia are preserved and closely packed within the gametophore. The gametangium wall is strongly mineralized and SEM observations show acicular aragonite crystals arranged perpendicularly to the wall surface. The occurrence of mineralized cyst walls distinguishes the new species from the other three species ascribed to the genus Acetabularia, namely Acetabularia miocaenica, Acetabularia chiavonica, and Acetabularia transylvana. Cyst wall biomineralization in A. moldavica sp. nov., Chalmasia, and Halicoryne appears to assist in distinguishing taxa at species level but not at genus level. Four types of intracellular biomineralization can be recognized in polyphysaceans according to the mineralization of cyst walls and intergametangial spaces. The attribution of an extant species to a fossil genus and vice-versa can be problematic when the fossil consists of a mineralized spicule (intracellular biomineralization). Two contrasting examples are Acetabularia schenckii (extant species) assigned to the genus Acicularia (fossil), and Halicoryne morelleti (fossil species) referred to an extant genus (Halicoryne). When it is unclear whether fossil taxa possessed one or two coronae, the attribution of Cenozoic species to an extant genus appears speculative. Therefore, we support the view that the genus Acicularia should only be applied to fossil species. In addition, mineralized aggregates of cysts of Halicoryne morelleti should be distinguished from their possible extant counterparts (Chalmasia, Halicoryne, and Acetabularia) when coronal structures are not preserved. In the literature Halicoryne morelleti has been compared with the fossil genera Sedalanella and Ioanella. The first genus must be considered a junior synonym of Oroseina. A new interpretation of the genus Ioanella is supplied. The two layers of cysts of Ioanella conform poorly with the small ellipsoidal calcareous bodies of Halicoryne morelleti. Therefore, we propose the new genus Patruliuspora for Halicoryne morelleti

    A new, fast method to search for morphological convergence with shape data

    Get PDF
    Morphological convergence is an intensely studied macroevolutionary phenomenon. It refers to the morphological resemblance between phylogenetically distant taxa. Currently available methods to explore evolutionary convergence either: rely on the analysis of the phenotypic resemblance between sister clades as compared to their ancestor, fit different evolutionary regimes to different parts of the tree to see whether the same regime explains phenotypic evolution in phylogenetically distant clades, or assess deviations from the congruence between phylogenetic and phenotypic distances. We introduce a new test for morphological convergence working directly with non-ultrametric (i.e. paleontological) as well as ultrametric phylogenies and multivariate data. The method (developed as the function search.conv within the R package RRphylo) tests whether unrelated clades are morphologically more similar to each other than expected by their phylogenetic distance. It additionally permits using known phenotypes as the most recent common ancestors of clades, taking full advantage of fossil information. We assessed the power of search.conv and the incidence of false positives by means of simulations, and then applied it to three well-known and long-discussed cases of (purported) morphological convergence: the evolution of grazing adaptation in the mandible of ungulates with high-crowned molars, the evolution of mandibular shape in sabertooth cats, and the evolution of discrete ecomorphs among anoles of Caribbean islands. The search.conv method was found to be powerful, correctly identifying simulated cases of convergent morphological evolution in 95% of the cases. Type I error rate is as low as 4-6%. We found search.conv is some three orders of magnitude faster than a competing method for testing convergence

    Biotic, mineralogical, petrographic, and geomorphological characterization of the Falerno-Domitio shoreline (Campania region, southern Italy), with implication for environmental health studies: preliminary results

    Get PDF
    We report the first results of an ongoing study related to the project FARO (i.e. the Italian “Fund for original research projects”, granted by the Università di Napoli Federico II and IMI bank partner). This research project aims to the enhancement of the physical and biotic features of the coastal landscape related to the Falerno-Domitio shoreline, located in the mid-north coast of the Campania region (southern Italy), from the Garigliano river and Torregaveta. In the national scenario, this area can be considered as a valuable “natural laboratory”, for its wildlife (i.e. the Natural Reserve Foce Volturno, the Regional Park of Campi Flegrei, etc.), famous archaeological sites (i.e. Cuma excavations), and peculiar geological and volcanological characteristics (i.e. Phlegraean Fields). Unfortunately, it also suffers for a strong pollution and environmental degradation due to human activities. The research consists of a multidisciplinary analysis, mainly based on a bathymetric sensing, sampling of both the sea bottom sediments and the beach sands; it comprises: 1) integrated monitoring of the quality of environmental health through a biological study, 2) geomorphological and sedimentological analyses of the area and of the whole sample sets, with GIS data processing, 3) taxonomic and ecological analyses of selected benthic meiofauna assemblages, 4) mineralogy, petrography and geochemistry of beach sands along the shoreline, as well as of sea bottom samples. A complete sampling work of the beach sands, from the Garigliano estuary to the Cuma site, has been done, and the results of mineralogical, petrographic and chemical features, mainly in relation to major and trace elements data, as well as the granulometric curves, are presented. The ecologic and eco-toxicological studies are also carried out on selected samples, revealing the structure of meiofauna (benthic foraminifers and ostracods) assemblages. Tests on the occurrence of the bio-indicator organism Artemia salina have also performed, showing a relatively low toxicity of the samples analysed up to now. Preliminary bathymetric data are also presented

    Norman Douglas e la geologia nella Terra delle Sirene / Norman Douglas and the Geology in the Siren Land

    No full text
    The geological aspects on the geology of Capri and Sorrento Peninsula occurring in the Douglas' novel Siren Land are showed and critically discussed

    LATE CRETACEOUS-PALEOGENE DASYCLADALEANS AND THE K/T BOUNDARY PROBLEM

    No full text
    Bibliographicadlataon LateCretaceous-Paleogendeasycladaleanis criticallyanalysedand updatedand the systematicapl ositionof some taxa is revised. Generaand species distributioanre checkedand plottedT. he compiledatasetcomparedwithevrdencesfrom lowerDanianshallowwatersuccessionsallowto prospecthatdasycladaleansufferedfrom thel(T boundarycrisis.InthiscontexttheupperDanian-Thanetiaintervalisconsidereda recoveryphase,the Ypresian-Lutetiaann intervalof stabilizationand a new crisisis hypothesizedstartingfrom the Bartonian.Finallya paleoecologicaslcheme for the dasycladaleaninstheDanianS, elandian-ThanetiandYpresian-Lutetiaisns, uppli

    Valutazione degli effetti da esposizione a nanoparticelle sulla plasticità fisiologica, nervosa e comportamentale in Octopus vulgaris

    No full text
    L'impiego di nanomateriali nell’ultimo decennio è fortemente aumentato. Nonostante la notevole velocità di sviluppo delle nanoscienze, ancora relativamente poco è noto circa le possibili interazioni degli oggetti su scala nanometrica con gli organismi viventi in ambiente marino. In questo studio, si è proposto, il polpo, O. vulgaris, come modello sperimentale per esplorare l’interazione con il nanoparticolato di diossido di titanio (nTiO2). A tal fine si sono testati due diverse vie di somministrazione. In un primo set sperimentale, gli animali sono stati esposti a nanoparticolato tramite iniezione e misurata la risposta di immunità cellulare emolinfatica; in un secondo, la somministrazione è avvenuta mediante cibo (cozze previamente esposte per 24 ore a nTiO2) e misurati gli effetti in termini di risposta comportamentale, del numero di cellule nervose e di espressione genica del cervello. Un incremento del numero degli emociti è stato registrato già dopo 4 ore la somministrazione di nanoparticolato. Inoltre, nTiO2 stimola un aumento dell' attività lisozimatica e della produzione di ossido nitrico nel emolinfa, inducendo stress ossidativo ad una concentrazione ≥ 1,0 mg / L. È stato evidenziato che la somministrazione di nanoparticolato interferisce con i normali processi di apprendimento in test di abituazione e di evitamento a 15 e 30 giorni dal trattamento. In associazione all’ esposizione a lungo termine si sono riscontrate significative evidenze iperplastiche ed ipertrofiche. Nanoparticelle di TiO2 producono alterazioni di espressione genica, dopo 3 giorni e due settimane, nelle diverse strutture costituenti il cervello. I risultati ottenuti dimostrano che la somministrazione mediante iniezione ed ingestione da nTiO2 determina significative risposte biologiche in seguito a breve e lunga esposizione interferendo con la risposta fisiologica, cellulare e comportamentale di O. vulgari
    corecore