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The first ophthalmosaurid ichthyosaur from the Upper Jurassic of the Umbrian–Marchean Apennines (Marche, Central Italy)
No full textThe first ophthalmosaurid ichthyosaur from the Upper Jurassic deposits of the Central–
Northern Apennines (Marche, Italy) is here described for the first time. The specimen is relatively
complete and is referred to Gengasaurus nicosiai gen. et sp. nov. based on a unique combination of
characters, including a peculiar condition of the preaxial accessory facet on the humerus. The faunal
association of the ichthyosaur-bearing level indicates a late Kimmeridgian – earliest Tithonian age,
and its finding contributes significantly to our knowledge of the diversity of Late Jurassic ichthyosaurs
from the Western Tethys. Two shark teeth assigned to the order Hexanchiformes were also recovered
in association with the ichthyosaur specimen, suggesting that scavenging of the carcass might have
occurred. Gengasaurus can be referred to Ophthalmosauridae based on the reduced extracondylar
area of the basioccipital, and the presence of a preaxial digit. It differs from Ophthalmosaurus spp.
in several respects, including the shape of the posterior basisphenoid, the shape of the supraoccipital,
the anteriorly deflected preaxial facet of the humerus, and a proximodistally shortened ulna. The new
taxon actually shares diagnostic characters with both members of the two main lineages recovered in
previous phylogenetic analyses,more nested within Ophthalmosauridae. The affinities of Gengasaurus
to genera from both the northern and southern hemispheres also suggest that connectivity between
pelagic habitats was high during the early Late Jurassic, allowing dispersal of some forms, followed
by local, endemic divergence
First occurrence of an ophthalmosaurid ichthyosaur in the Upper Jurassic of the Northern Apennines (Marche, Central Italy): stratigraphic setting
No full textAn ophthalmosaurid ichthyosaur was discovered in Upper Jurassic deposits of the Umbria-Marche sedimentary succession near Genga (Ancona, Marche, Italy). While other Mesozoic marine reptiles have been found at different stratigraphic intervals in Italy, this specimen represents the first ichthyosaur ever recorded from the Upper Jurassic of the Apennines. It consists of an almost complete skeleton preserved on a slab, with an articulated vertebral column, and disarticulated skull and pectoral girdle. This paper describes the stratigraphy of the ichthyosaur-bearing deposits.
The Umbria-Marche sedimentary succession is characterized by Meso-Cenozoic pelagites and hemipelagites overlying Lower Jurassic shallow-water carbonates (Calcare Massiccio Fm.). The rifting stage, which affected the Western Tethys in the Early Jurassic, produced a complex submarine architecture, resulting in a mosaic of variable facies and thickness differences in the syn- and post-rift succession. Extension linked with opening of the Liguria - Piedmont Ocean dismembered and drowned a huge carbonate platform (Calcare Massiccio paleoplatform), and converted it into a system with small horsts-and-grabens/semigrabens, where pelagic deposits capped the shallow-water carbonates. The original Early Jurassic paleobathymetric differences were levelled by Early Cretaceous times. The basin-fill deposits onlapped the (mostly pre-rift) Calcare Massiccio facies, exposed at the footwall of Jurassic faults in the form of paleoescarpments, and buried the structural highs while their margins were largely inactive. The area in which the ichthyosaur was found was characterized by numerous structural highs (Mt. Murano, Mt. Revellone, Mt. Scoccioni and Mt. Valmontagnola), onlapped by the Jurassic - Early Cretaceous basin-fill units. In the Middle Jurassic, a huge block (about 0,7 km longer axis) of Calcare Massiccio - characterizing the Il Sassone sector - collapsed from the western escarpment of the Mt. Scoccioni or from the Mt. Revellone high, due to tectonic/gravitative instability. The olistolith was embedded in the “Calcari e marne a Posidonia” Fm. (late Toarcian-?late Bajocian), and subsequently was onlapped by the “Calcari Diasprigni” (?late Bajocian-early Kimmeridgian) and “Calcari ad aptici e Saccocoma” (Kimmeridgian p.p.-early Tithonian) Fms. Additional stratigraphic evidence for tectonic instability across the study area is found in the Middle Jurassic with gravity flow deposits, slumps and breccias bearing Calcare Massiccio clasts.
The specimen was discovered in the Upper Jurassic deposits onlapping the Il Sassone mega-olistolith. It was embedded in green and reddish limestones and cherty-limestones referable to the “Calcari ad aptici e Saccocoma” Fm. The faunal assemblage includes belemnites (Duvalia spp.), aptychi (Laevaptychus sp., ?Laevilamellaptychus sp.), rhyncholites (Leptocheilus sp.), shark teeth (hexanchiforms), trace fossils (Thalassinoides sp., Chondrites sp.), radiolarians, calcisphaerulids and abundant Saccocoma tenella. These elements, coupled with the absence of S. vernioryi, Chitinoidella spp. and calpionellids, constrain the age of the ichthyosaur to the late Kimmeridgian - earliest Tithonian
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
New insights on the sedimentological and biostratigraphic record of the Upper Cretaceous of the Salento Peninsula (Apulia, Southern Italy): collecting data from an abandoned quarry near Manduria
No full textThe analysis of vertebrate material from the Salento Peninsula (Italy), currently stored at the Museum of Paleontology
of the University of Rome ‘Sapienza’ and the Natural History Museum in Verona, led us to conduct a preliminary field
survey and prospection in order to localize suitable outcrops for paleontological excavations. As a result, new stratigraphic
and sedimentological features of the Cretaceous limestones of the Apulian Carbonate Platform are here reported. The
attention was focused on the northern sector of the Salento Peninsula, and in particular on an abandoned quarry about 2
km NE of Manduria (Taranto, Italy). About 8 meters of Upper Cretaceous ‘Plattenkalke’-type deposits referable to the
Calcare di Altamura Fm., showing interesting paleontological and geological aspects, are here exposed. A high-resolution
litho-biostratigraphical study of the succession was performed at a mm-scale in order to reconstruct the paleoenvironment
setting of the area.
From a stratigraphic and sedimentological point of view, the lithotypes outcropping in the quarry are dominated by
the cyclic alternation of: i) mm- to cm-thick, dome-shaped, cyanoalgal laminites, sometimes cross-cut by mud-cracks; ii)
‘fenestral’ horizons made of prismatic-to-discoidal voids, in some cases larger than 1 cm, related to dissolution of
evaporitic salts (mainly sodium chloride); iii) wedge-shaped pedogenetic horizons (terre rosse) and paleokarst structures,
sometimes associated with syn-sedimentary tectonics.
From a paleontological point of view, a unique and well-preserved thanatocoenosis characterizes the studied
succession. The macrofauna is strictly oligotypic and consists of fish-remains, coprolites, regular sea urchins and few
specimens of Chondrodonta sp., while the microfauna is totally absent. The main feature is represented by the kind of
preservation of the echinoids and their spines. In fact, echinoids are preserved as “ghosts”, with the original high-Mg
calcitic test completely leached. The moulds are partially filled by yellow-orange silt and clay, referable to incipient
paleokarst features, or by crusts of microcrystalline calcite. Furthermore, a large number of isolated radioli were found,
while no echinoid tests with articulated spines were recovered.
The facies analysis of the “vuggy” and laminated limestones suggests a saline and dry, supratidal mudflat-type setting
as depositional environment. Hypersaline conditions are highlighted by salt-rich levels, while periodical and ephemeral
flooding of normal-salinity seawater allowed the colonization of the sea floor by benthic organisms (mainly echinoids),
and occupancy by fishes. Extreme conditions of the depositional setting are marked by the total lack of the microfauna.
Finally, the occurrence of occasional wet phases also led to the development of soils and karstic phenomena
Potential Lagerstätte-type beds in the Upper Cretaceous of the Salento Peninsula (Apulia, Italy)
No full textThe recovery of an exceptionally well preserved pythonomorph lizard from the
Apulian Platform (southern Italy), together with other well-preserved and undescribed
vertebrate remains in the collections of the Natural History Museum of Verona from the
same deposits, led to an investigation of some interesting but so far understudied fossil
localities in southern Italy.
The deposits of interest outcrop on the Salento Peninsula (Apulia) and are Upper
Cretaceous in age. They are particularly famous for the abundance of a well-preserved
and characteristic ichthyofauna. Other well-preserved vertebrates have been recovered
from the same localities, but are still undescribed. The geology of this area has been
poorly investigated and the resolution of the geological datum on a regional scale is
untrustworthy; the stratigraphic age of these fossil-rich horizons is dated as Campanian-
Maastrichtian according to the biostratigraphy (nanoplankton, rudists), or Santonian-
Coniacian based on isotopes. In order to improve our knowledge of the geology of the
area, we carried out sedimentological studies (facies analysis and composition) intended
to identify the most fossiliferous beds.
The new pythonomorph lizard was recovered from a small outcrop outside the
town of Nardò (Lecce, Apulia), is the first complete basal pythonomorph (Squamata,
Dolichosauridae) from southern Italy, and is particularly important since both
mineralized scales and muscles are preserved together with the skeleton. The fossil is
extremely important also for stratigraphic and palaeogeographical reasons: it significantly
extends the temporal range of dolichosaurs from the Cenomanian-Turonian boundary to
possibly the Coniacian-Santonian, or even as young as the Campanian-Maastrichtian.
This new specimen fills the palaeogeographical gap in the fossil record of basal
pythonomorphs of the Tethyan realm – described material since now was from the
Mediterranean of Africa (Lebanon), the Dalmatian Domain (Croatia, Slovenia), and
southeast England.
This project aims to understand the stratigraphic relationships and
palaeoenvironmental conditions characterizing these vertebrate-rich deposits, very likely
with important repercussions on both the palaeogeography and geodynamics of the
Mediterranean portion of the Tethys. An improvement in the resolution of the
palaeogeographic arrangement of the Apulian Platform during the Upper Cretaceous will
also allow better understanding of the radiation and distribution of basal pythonomorphs
(e.g., dolichosaurs), which seems to be restricted to the Western Tethys
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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