1,721,212 research outputs found
Perturbazioni climatiche del Paleogene: la testimonianza dei sedimenti di mare profondo del bellunese
No full textLenticulina polymorpha (Terquem, 1870) (Foraminiferida, Lagenida) nel Batoniano di Posada, Sardegna orientale
No full textPosadia feroniensis n. gen., n. sp (Lituolida, Hormosinidae) from the Bathonian of Sardinia, Italy
No full textDetailed stratigraphical and paleobiological studies on
the Mesozoic carbonate platform of eastern Sardinia (Italy)
revealed the occurrence of an unknown foraminifer
in the Bathonian (Middle Jurassic) Dorgali Dolostone
cropping out in the Posada hill. Posadia feroniensis n.
gen., n. sp., a new distinctive agglutinated foraminifer
referable to the family Hormosinidae Haeckel, 1894, is
formally described and figured. Posadia is morphologically
characterized by an uniserial, roughly finished test
with inverted ‘‘V’’-like chambers in longitudinal section
Estinzioni di massa e biodiversità dal punto di vista di un paleontologo (le estinzioni di massa: il motore della biodiversità )
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Benthic foraminiferal response to the Middle Eocene Climatic Optimum in the South Atlantic (ODP Site 1263) and central-western Tethys (Alano section, NE Italy): a comparison.
No full textDuring the Middle Eocene Climatic Optimum (MECO; 40 Ma), one of the major short-term Cenozoic climatic
perturbations, the cooling trend of the middle Eocene was interrupted by transient (500 Kyr) global warming
of upper and deep ocean waters (Bohaty et al., 2009). MECO represents a large climatic disruption, but its
paleoenvironmental changes and effects on biota are poorly constrained.
To provide insight into the effects of MECO and their regional variability on deep-sea biota, we present benthic
foraminiferal data from lower-bathyal ODP Site 1263 (SE Atlantic), and compare these with the record from
the middle-bathyal Alano section, located closer to the continental margin in the central-western Tethys (NE
Italy; Boscolo Galazzo et al., 2013). The record of MECO at Site 1263 is continuous and not affected by CaCO3
dissolution, allowing study of the nature and causes of benthic foraminiferal change in a pelagic setting remote
from the continents.
The MECO did not induce a severe species turnover of benthic foraminiferal assemblages at Site 1263, but
warming was paralleled by a marked decrease in benthic foraminiferal accumulation rates (BFAR). The decrease
in BFAR combined with benthic assemblage changes indicates a decrease in supply of food to the sea floor, thus
increased oligotrophy. Comparison of benthic foraminiferal data and surface-to-bottom 13C gradients at Site
1263, indicates that increased stratification and declining surface primary productivity were not the principal
cause of the decrease in food flux to the sea floor. We argue that warming may have been mainly responsible for
the reduction of the flux of organic matter to the sea floor, increasing the metabolic rates of pelagic consumers
more than those of primary producers and leading to increased remineralization of organic matter in the water
column. In addition, sea-floor warming would increase metabolic rates of benthic foraminifera and their food
requirements, reducing the effective food supply. Our benthic foraminiferal records show that at Site 1263 the
MECO did not induce large paleoceanographic (e.g., circulation, productivity) changes, and the changes in the
benthic community may have been caused by the warming itself, rather than by its indirect environmental effects.
This scenario strongly differs from that for the Alano section, where delivery of food to the sea floor increased
during the gradual warming of MECO, causing a significant but transient restructuring of benthic foraminiferal
fauna. Deposition of organic-rich sediments and multiple peaks in abundance of bi-triserial opportunistic benthic
foraminiferal taxa indicate that peak warming during MECO was immediately followed by severe eutrophication.
The enhanced hydrological cycle during MECO may have led to increase in the delivery of nutrients into this
marginal basin, thus increased primary productivity, enhanced delivery of organic matter to the seafloor, and
consequent development of dysoxic sea-floor conditions. The comparison of benthic foraminifera at Site 1263 and
the Alano section shows that the effects of MECO warming greatly varied geographically and bathymetrically,
with different environmental stressors affecting benthic foraminiferal assemblages
A RUPELIAN CORAL REEF FISH ASSEMBLAGE FROM THE VENETIAN SOUTHERN ALPS (BERICI HILLS, NE ITALY)
Full text linkHere we describe a new bony fish assemblage collected from a fossiliferous outcrop located in Perarolo, Berici Hills, Venetian southern Alps. The fossiliferous deposits pertain to the Rupelian (lower Oligocene) Castelgomberto Calcarenite and are indicative of a tropical marine shallow water setting associated with coral reefs. The assemblage is characterized by diminutive putative cryptobenthic fishes, including a single goby (family Gobiidae) and several cardinalfishes of the subfamily Pseudmiinae (family Apogonidae. Furthermore, a new apogonine of the extinct tribe †Eoapogonini, a new butteflyfish (family Chaetodontidae), and an indeterminate viviparous brotula belonging to the ophidiiform family Dinematichthyidae, are also present, and likely represented part of the epibenthic community. Some of the taxa described herein are among the first occurrences for their respective lineages in the fossil record. The Perarolo taxa document the first Oligocene coral reef fish assemblage known to date. Four taxa are described as new: †Arconiapogon deangelii gen. et sp. n., †Chaetodon (Blumchaetodon) wattsi subgen. et sp. n., †Oligopseudamia iancurtisi gen. et sp. n., and †Oniketia akihitoi gen. et sp. n
Nomenclatural reassessment of Justitia desmaresti (Crustacea, Decapoda, Palinuridae) from the lower Eocene of Bolca (Verona, NE Italy)
No full textA close examination of the available literature and documentation concerning the nomenclatural history of the Eocene palinurid, Justitia desmaresti, indicates that the authorship of this taxon should be attributed to Secrétan (1975) and not to Massalongo (1854), as recently stated by Garassino & Novati (2001). As a consequence of the reassessment, we propose here the designation of the lectotype from the syntypes originally figured by Secrétan (1975). An exhaustive list of synonyms summarizing the nomenclatural history of the taxon is also given
Ricostruzione storica e riscoperta di Cycadeoidea veronensis (Spermatophyta) nel Museo di Storia Naturale di Verona [History and rediscovery of Cycadeoidea veronensis (Spermatophyta) in the Museum of Natural History of Verona]
No full textThis paper unveils the history of the fossil cycadacean Cycadeoidea veronensis, recovered at Verona in the mid of eighteen century and almost forgotten since the early nineteen century. The careful investigation of available literature and recently published documents, along with the examination of historical material housed in some museums allowed to identify the original specimen, displayed, but mislabeled, at the Museum of Natural History of Verona. The reconstruction of the nomenclatural history of C. veronensis indicates that the authorship of this taxon must be attributed to Solms-Laubach in Capellini and Solms-Laubach (1892). Furthermore, the micropaleontological investigation of the rocky matrix associated with the specimen allowed to assign C. veronensis to the lower part of Lower Cretaceous (upper Berriasian-upper Valanginian). The fossil represents the only one firmly dated Cycadeoidea's specimen so far recovered in Italy
A partial associated tooth set of the genus Ptychodus from the Upper Cretaceous of northeastern Italy
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