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

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 ( =  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 Dmean values ranging between 192 and 199 µm). The embryon diameters of O. multiplicatus, recorded only in SBZ 4, range between 300 and 319 µm 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

Spatial and temporal facies evolution of a Lower Jurassic carbonate platform, NW Tethyan margin (Mallorca, Spain)

The variety of depositional facies of a Lower Jurassic carbonate platform has been investigated on the island of Mallorca along a transect comprising six stratigraphic profiles. Twenty-nine facies and sub-facies have been recognized, grouped into seven facies associations, ranging in depositional environment from supratidal/terrestrial and peritidal to outer platform. Spatial and temporal (2D) facies distribution along the transect reflects the evolution of the carbonate platform with time showing different facies associations, from a broad peritidal platform (stage 1) to a muddy open platform (stage 2), and finally to a peritidal to outer carbonate platform (stage 3). Stage 1 (early Sinemurian to earliest late Sinemurian) corresponds to a nearly-flat peritidal-shallow subtidal epicontinental platform with facies belts that shifted far and fast over the whole study area. The evolution from stage 1 to stage 2 (late Sinemurian) represents a rapid flooding of the epicontinental shallow platform, with more open-marine conditions, and the onset of differential subsidence. During stage 3 (latest Sinemurian), peritidal and shallow-platform environments preferentially developed to the northeast (Llevant Mountains domain) with a rapid transition to middle-outer platform environments toward the northwest (Tramuntana Range domain). Stages 1 and 3 present facies associations typical of Bahamian-type carbonates, whereas stage 2 represents the demise of the Bahamian-type carbonate factory and proliferation of muddy substrates with suspension-feeders. The described platform evolution responded to the interplay between the initial extensional tectonic phases related to Early Jurassic Tethyan rifting, contemporaneous environmental perturbations, and progressive platform flooding related to the Late Triassic–Early Jurassic worldwide marine transgression and associated accommodation changes

Re-description of Cymopolia miocenica (Karrer) (Chlorophyta, Dasycladales) from the Late Miocene of Sicily and the Middle Miocene of Banat (Romania)

Professor Giuliano Ruggieri found a rich dasyclad flora in siliciclastic sediments of a Late Miocene (lower Messinian) succession from Sicily (Petralia Sottana, Palermo). The algal remains belong to the genus Cymopolia Lamouroux (Cretaceous-Recent). Morphological and biometrical characters allow the Sicilian taxon to be attributed to Cymopolia miocenica, a species formerly described by Karrer in 1868 as Dactylopora miocenica, and known only in the Middle Miocene of the Paratethys area (Romania and Hungary). A lectotype, chosen among Karrer’s material housed in the Naturwissenschaften Museum of Vienna, is here indicated. The remains of Cymopolia miocenica consist of sterile and fertile calcareous articles. The sterile bodies are usually cylindrical, while the fertile ones are elongated to short barrel-shaped. All the articles are strongly calcified except around the outer swollen part of primary laterals of fertile whorls. The original aragonitic calcification looks still preserved, a fact probably related to the conservation in clay. The calcified structure exhibits the same pattern as in the extant species. A reconstruction of the alga is supplie

Error vacuo, Detecting Structures in Poorly Calcified Jurassic Dasycladales

Several Jurassic dasycladalean genera (e.g. Pseudoclypeina, Palaeodasycladus, Eodasycladus, Chinianella and Cylindroporella) display a complex structure which, owing to a deficit of calcification, is difficult to interpret. This lack of calcification causes a loss of certain soft algal structures and complicates the work of the specialist responsible for interpreting the algal anatomy as well as the corresponding position in the systematics. A key of interpretation is given, and case histories are discussed

Evidence of external gametophores in puzzling Late Triassic-Early Jurassic dasycladalean green algae

The mineralized cover preserving soft parts of the Dasycladales, as an external mould, is the only tool allowing to deduce the anatomical parts of these algae. Problems arise when voids within the calcareous skeleton do not reflect accurately the original soft parts due to a loss of mineralization. Based on a rich material collected from the type locality in Languedoc (France), a detailed study was carried out on Chinianella ellenbergeri, the type species of Chinianella. Previous interpretation of voids in the calcified fossil considered the alga to be made of an alternation of fertile and further ramified sterile whorls. Our study shows that large cavities previously interpreted as corresponding to fertile whorls, actually denote empty spaces. Therefore, the alga essentially consists of spaced-out whorls of sterile primary laterals, distally bearing a tuft of three-four phloiophorous secondary laterals. A small number of specimens show the presence of calcified structures interpreted as corresponding to external, subterminal reproductive organs. Consequently, an emended diagnosis is proposed for C. ellenbergeri and for the Chinianella. Present interpretation of Chinianella adds a new step to the understanding of the emergence of external reproductive organs during the geological history of this group of green algae. Chinianella ellenbergeri shows that choristosporate reproduction sensu lato was already well represented and diversified in the Early Jurassic. Other Late Triassic-earliest Jurassic species formerly attributed to Chinianella (namely C. carpatica, C. crosii, C. zanklii, C. micropora, and C. macropora) reveal that the large, fertile primary lateral is a compound pore with a structure like in Cymopolia, i.e., made of a short primary lateral with a terminal gametophore embraced by secondary laterals. Therefore, these species have been referred to the new genus Distefanopolia

Deciphering voids in dasycladales, the case of dragastanella transylvanica, a new lower cretaceous triploporellacean genus and species from Romania

Dragastanella transylvanica n. gen. n. sp. is described. Its calcified skeleton contains numerous voids, partly related to the molds of soft parts of the alga, but also related to lack of calcification. Interpretation of these voids, especially their attribution to original structures (e.g., primary lateral versus reproductive organ), has important implications for the taxonomic position of the alga, even at the family level. Examination of key sections that include the boundary between sterile and fertile parts of the alga excludes the occurrence of external reproductive organs. Unusual, paired pores in the outer part of the mineralized skeleton reflect an asymmetry within the whorl, excluding the presence of secondary laterals. The alga is characterized by a cylindrical to club-shaped thallus bearing only phloiophorous primary laterals arranged in whorls and flaring outwards, forming a cortex. Mineralized lenticular reproductive organs containing cysts set in the equatorial plane (Russoella-type gametophores) occur inside primary laterals (cladosporous arrangement of the reproductive organs). These characters support establishment of the new genus Dragastanella. Dragastanella transylvanica n. gen. n. sp. resembles species previously referred to Zittelina (Zittelina hispanica and Zittelina massei) and Triploporella (Triploporella matesina and Triploporella carpatica). Except for Triploporella carpatica, whose mineralized skeleton does not permit confident attribution to either Triploporella or Dragastanella n. gen., the other species must be ascribed to Dragastanella n. gen. Therefore, the following new combinations are proposed: Dragastanella hispanica n. comb., Dragastanella massei n. comb., and Dragastanella matesina n. comb. Despite widely overlapping biometrical measurements, these species can be differentiated by the size and location of their reproductive organs, the pattern of calcification around the primary laterals, and relationships among structural parameters such as the size of laterals, number of laterals per whorl, and distance between whorls

Site 1-Early Cretaceous of Monte Faito

It is illustrated the algal content occurring int the Lower Cretaceous Mt. Faito successio

Le pagine dell'isola. Capri negli scritti e nelle memorie di Norman Douglas, Oscar Wilde e Pablo Neruda. Con documenti inediti

Il volume raccoglie contributi su scrittori, poeti ed artisti stranieri che hanno soggiornato a Capri. E' presente anche un contributo sulla balneabilità delle acque dell'isola

Pseudoclypeina distomensis n.sp. (green algae, dasycladales) from the Malm of the Greece

A new species of a dasycladalean green alga is described from the Upper Jurassic of Greece: Pseudoclypeina distomensis