 Subjects -> PALEONTOLOGY (Total: 43 journals)
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- FIRST JURASSIC EVIDENCE OF A POSSIBLE SPINOSAURID PEDAL UNGUAL, FROM THE
JAISALMER BASIN, INDIA
Authors: ARCHANA SHARMA, FERNANDO E. NOVAS, SANJAY SINGH
Abstract: We describe an isolated, almost complete pedal ungual phalanx from the Middle Jurassic marine carbonate rocks of the Jaisalmer Basin, Rajasthan, north-western India. The ungual bone is triangular shaped, pointed, elongated, asymmetrical, dorsoventrally compressed, ventrally flat, bearing a shallow semi-circular excavation, and almost straight in lateral view. The morphological features, as well as its proportions closely resemble the pedal ungual phalanges of spinosaurid theropods, presently known dominantly from the Cretaceous. The affinity to spinosaurids is supported by bivariate and multivariate analyses. The ungual phalanx is tentatively identified as a basally branching Jurassic spinosaurid under Megalosauroidea. Considering the stratigraphical and geographical provenances, this contribution may represent the oldest record of a spinosaurid.
PubDate: 2023-10-27
DOI: 10.54103/2039-4942/20032
Issue No: Vol. 129, No. 3 (2023)
- THE MIDDLE EOCENE CLIMATIC OPTIMUM (MECO) IMPACT ON THE BENTHIC AND
Authors: ANTONELLA GANDOLFI , VICTOR MANUEL GIRALDO-GÓMEZ , VALERIA LUCIANI , MICHELE PIAZZA, THIERRY ADATTE, LUCA ARENA, BRAHIMSAMBA BOMOU, ELIANA FORNACIARI, GIANLUCA FRIJIA, LÁSZLÓ KOCSIS, ANTONINO BRIGUGLIO
Abstract: We present here new quantitative analyses of planktic and benthic foraminifera to assess the impact of the Middle Eocene Climatic Optimum (MECO, ~40 Ma) on these biotic groups studied along a shallow-water succession rich in larger benthic foraminifera (Sealza, Liguria, NW Italy). The MECO is one of the major Eocene global warming events, characterized by ~4–6°C warming, shifts in the global carbon cycle, and rise in atmospheric pCO2. The Sealza succession is interpreted as the product of a drowning ramp influenced by tectonic activity and provides an exceptional chance to compare biotic variations in shallow-water assemblages with deep-water communities across the MECO. In the section, the MECO interval is tentatively constrained by stable isotope oxygen data and calcareous plankton biostratigraphy. The marked decline in abundance of the epifaunal benthic Cibicidoides across the lower-middle part of the MECO suggests a decrease in oxygenation at the seafloor. Further evidence of oxygen depletion is the increase in organic matter content (TOC) of the sediment and the presence of infaunal genera Uvigerina and Bolivina. The planktic foraminiferal assemblages record the MECO warming in the upper water column as the mixed-layer warm index genera Acarinina and Morozovelloides markedly increase in abundance. In the post-MECO interval, here poorly exposed, cooler conditions are indicated by the dominance of the cold-water index genus Subbotina. Remarkably, Acarinina decline in abundance in the upper MECO interval and never recover. The MECO perturbance permanently impacted the benthic and planktic communities at Sealza that exceeded the tipping point to move to a new regime, thus proving the fauna to be not resilient, but also not recording any extinctions.
PubDate: 2023-10-17
DOI: 10.54103/2039-4942/20154
Issue No: Vol. 129, No. 3 (2023)
- BIOSTRATIGRAPHY AND PALEOENVIRONMENTAL ANALYSIS OF THE LOWER MIOCENE QOM
FORMATION (JAAM AREA, CENTRAL IRANIAN BASIN)
Authors: BOTOND LÁZÁR, MOSTAFA FALAHATGAR, MEHDI SARFI, MĂDĂLINA-ELENA KALLANXHI, RAMONA BĂLC, LÓRÁND SILYE
Abstract: Lower Miocene sediments from a previously not investigated outcrop of the Qom Formation (Central Iranian Basin) were studied for their foraminiferal and calcareous nannofossil content. The studied stratigraphic record is assigned to the upper part of calcareous nannofossil NN2 Zone/CN1c Subzone and to the benthic foraminiferal Borelis melo melo Zone of Burdigalian age. The diversity indices, benthic foraminiferal morphogroups, and quantitative analyses of assemblages (principal component and cluster analysis) suggest an overall shallow-marine depositional environment. This interpretation is well constrained based on the dominance of the B1 benthic foraminifera morphotype with biconvex, trochospiral calcareous test, and epifaunal habitat. The identified six cluster groups of benthic foraminiferal assemblages are confirmed by the principal component analysis too, and their distribution along the studied section argue for dynamic changes of the environment. This is well exemplified by a more or less constant shallowing, then deepening trend of the environment as revealed by the shifting from the high diversity, shallow-shelf assemblages of Cluster 5 and 6 toward the low diversity, near-shore Ammonia tepida and Porosononion subgranosus assemblage (Cluster 1), and back.
PubDate: 2023-10-16
DOI: 10.54103/2039-4942/18651
Issue No: Vol. 129, No. 3 (2023)
- EOCENE RHAMPHOSIDAE (TELEOSTEI: SYNGNATHIFORMES) FROM THE BOLCA
LAGERSTÄTTE, ITALY
Authors: PIETRO CALZONI, JACOPO AMALFITANO, LUCA GIUSBERTI, GIUSEPPE MARRAMÀ, GIORGIO CARNEVALE
Abstract: The Rhamphosidae is an extinct family of syngnathiform fishes from the lower Eocene deposits of Europe, primarily known from specimens derived from the Ypresian Konservat-Lagerstätte of Bolca (Verona province, Italy). A descriptive analysis of 28 specimens of Rhamphosus from Bolca revealed the existence of six species, showing a greater taxonomic diversity compared to the previous scenario of only two species (the type species Rhamphosus rastrum and Rhamphosus biserratus). Four new species are established herein: Rhamphosus bloti n. sp., characterized by a peculiar and unique rostrum with a discoid shape; Rhamphosus brevirostris n. sp., which exhibits a moderately large size associated with a relatively short rostrum; Rhamphosus longispinatus n. sp., characterized by having the longest dorsal-fin spine and rostrum of all the Rhamphosus species; Rhamphosus tubulirostris n. sp., which shows a peculiar slim rostrum, long-based dorsal and anal fins, and a unique squamation characterized by the presence of numerous bucklers. The species from Bolca are also compared to the only other known Rhamphosus species, Rhamphosus rosenkrantzi, from the Fur Formation, Denmark. A number of morphological features support the assignment of the Rhamphosidae to the syngnathiform clade Dactylopteroidei, together with the extant families Dactylopteridae and Pegasidae, representing the sister group to the Pegasidae.
PubDate: 2023-10-03
DOI: 10.54103/2039-4942/20707
Issue No: Vol. 129, No. 3 (2023)
- AN INSIGHT INTO THE SYSTEMATICS OF PLICATOSTYLIDAE (BIVALVIA), WITH A
DESCRIPTION OF PACHYGERVILLIA ANGUILLAENSIS N. GEN. N. SP. FROM THE
LITHIOTIS FACIES (LOWER JURASSIC) OF ITALY
Authors: RENATO POSENATO, GAIA CRIPPA
Abstract: The Lithiotis facies represents an Early Jurassic global bioevent characterized by a remarkable spread of gregarious bivalves, which produced large sedimentary bodies in tropical shallow-water marine environments. The most peculiar and common genera Lithiotis, Cochlearites and Lithioperna, with aberrant and extremely elongated or strongly flattened shells, have been studied since the second half of the nineteenth century. Despite numerous systematic studies, their phylogenetic relationship with the other bivalve families is still uncertain. The Lithiotis facies yields other bivalve genera, among which a large multivincular mytiloid, provisionally determined as Isognomon (Mytiloperna) sp. ind. or Mytiloperna sp., is recorded in the literature. This taxon is here studied from a systematic point of view to clarify its taxonomic position and solve the open nomenclature adopted in the past. Here, we propose a new genus Pachygervillia and a new species Pachygervillia anguillaensis. The stratotype is located in the lower part of the Rotzo Formation (Calcari Grigi Group, Lower Jurassic), while the type locality is in the Lessini Mountains (Verona Province, Trento Platform, Southern Alps). This new species is characterized by a thick aragonitic inner shell layer with a fibrous, irregular, spherulitic, prismatic microstructure combined with a nacreous middle layer, both also occurring in species of the genera Lithiotis and Cochlearites of the family Plicatostylidae. This microstructural layering is here proposed as the main taxonomic character of the family, which is here emended and divided into the following two subfamilies: Plicatostylinae, yielding Lithiotis and Cochlearites with stick-like shells, and Pachygervilliinae nov. subfam., yielding Gervilleioperna, Lithioperna, Pachygervillia n. gen., and Pachyperna, previously placed within the subfamily Isognomoninae.
PubDate: 2023-09-13
DOI: 10.54103/2039-4942/20273
Issue No: Vol. 129, No. 3 (2023)
- SIDELINED SEASHELLS: REAPPRAISAL OF THE MIDDLE TRIASSIC AMMONOIDS OF
SAMOBOR AND ŽUMBERAK MTS. (NORTH-WESTERN CROATIA) AND THEIR SYSTEMATICS
AND BIOSTRATIGRAPHIC IMPLICATIONS
Authors: FRAN VIDAKOVIĆ, ROBERT ŠAMARIJA, JASENKA SREMAC, DRAŽEN JAPUNDŽIĆ
Abstract: Basinal Middle Triassic successions of the Samobor and Žumberak Mts. (north-western Croatia) have historically produced fossils of ammonoids. These finds have, however, largely been neglected in the later literature. This paper describes and redescribes a large collection of ammonoids, most of which were collected by previous researchers throughout the 20th century. Aside from the detailed taxonomic descriptions and revisions, several taxa previously unknown from these localities were identified. Of the species whose holotypes were designated at the Gregruć Breg locality, some are found to be dubious, with validity of other remaining inconclusive and a single taxon, Eoprotrachyceras dorae comb. nov., being treated as valid. Certain Middle Triassic ammonoid genera may also require future comprehensive revisions. A preliminary, modified ammonoid zonal/sub-zonal scheme for the Ladinian of the Tethyan province is proposed, to be inclusive of most of the data from the literature. The need for improvement of the subdivision of this stage is recognized. Based on ammonoids, condensed red nodular limestones of the Gregurić Breg locality (Samobor Mts.) most likely span the Avisianum subzone (upper Illyrian) – Longobardicum subzone (“middle” Longobardian), indicating that subsidence began in the earlier part of the Illyrian. At Mt. Žumberak, scant ammonoid remains indicate that the upper, limestone-rich portion of this succession spans at least the Avisianum subzone (upper Illyrian) – Longobardicum subzone (“middle” Longobardian), but additional data is needed for drawing more robust conclusions. Overall, the timing of basinal deposition is well correlated between Gregurić Breg and Žumberak localities (lower Illyrian – upper Longobardian).
PubDate: 2023-09-07
DOI: 10.54103/2039-4942/19942
Issue No: Vol. 129, No. 3 (2023)
- CARNIVORA FROM THE EARLY PLEISTOCENE OF GRĂUNCEANU (OLTEŢ RIVER VALLEY,
DACIAN BASIN, ROMANIA)
Authors: LARS WERDELIN, VIRGIL DRĂGUŞIN, MARIUS ROBU, ALEXANDRU PETCULESCU, AURELIAN POPESCU, SABRINA CURRAN, CLAIRE E. TERHUNE
Abstract: The Grăunceanu site in the Olteţ River Valley has yielded a rich carnivoran assemblage including at least 10, possibly 11 species: Vulpes alopecoides, Nyctereutes megamastoides, Ursus etruscus, Meles thorali, Lutraeximia sp., Pliocrocuta perrieri, Lynx issiodorensis, Puma pardoides, Megantereon cultridens, Homotherium latidens and possibly Pachycrocuta brevirostris. The faunal assemblage is compared with approximately coeval sites Europe and western Asia. This comparative analysis shows that the Grăunceanu assemblage shows the greatest similarities with sites to the west such as Senèze and, particularly, Saint-Vallier, rather than more easternly ones such as Liventsovka and Dmanisi. The relative abundance of the taxa at Grăunceanu was compared to that of Saint-Vallier and broad similarities were found, except for the absence of some cursorially adapted taxa present at Saint-Vallier but absent from Grăunceanu. The absence at Grăunceanu of taxa with a reconstructed cursorial hunting strategy, such as Chasmaporthetes and Acinonyx, may suggest less open habitat at Grăunceanu than indicated in previous paleoenvironmental reconstructions.
PubDate: 2023-09-06
DOI: 10.54103/2039-4942/20015
Issue No: Vol. 129, No. 3 (2023)
- COMMON AND RARE LOWER PLIOCENE AGGLUTINATED FORAMINIFERS OF PIEDMONT
(NORTHWESTERN ITALY): DISTRIBUTION, TAXONOMY AND PALEOENVIRONMENT
Authors: DONATA VIOLANTI
Abstract: Agglutinated foraminiferal taxa from five stratigraphic sections and eightheen small outcrops of Lower Pliocene deposits were quantitatively analyzed for paleoenvironmental purposes. The studied area is located in Piedmont, northwestern Italy, and includes the northeastern Monferrato, the southern margins of the Turin Hill, the Astigiano, the Albese and part of the Langhe. Studied samples were mainly collected in the marine Argille Azzurre (AA) Formation, and cover a time interval ranging from the MPl1 zone to the MPl4a subzone in the Pliocene Mediterranean Foraminiferal Zonation. Most of the agglutinated assemblages are dominated, or exclusively made, by calc-agglutinated infaunal species of elongated tapered or subcylindrical shape, mainly represented by Bigenerina nodosaria and Martinottiella communis. The deep-water infaunal Cylindroclavulina rudis, Eggerella bradyi and Martinottiella perparva characterized the open-sea basinal facies deposited in the central part of the Piedmont region during the earliest Pliocene. These taxa progressively decreased in abundance until to disappear, and were replaced in the upper silty succession by shelf taxa, dominated by Bannerella gibbosa and Textularia aciculata. In particular, T. aciculata showed its highest abundances in infralittoral to shallow circalittoral muddy sediments of probable fluvial origin, widespread in the Astigiano area, and could be suggested as a typical species of shallow marine delta deposits. Among the 42 agglutinated species here determined, Cyclammina cancellata and Reophax scorpiurus were seldom reported in previous works, Ammobaculites agglutinans, Ammoscalaria spp., Cribrostomoides subglobosus subglobosus, Haplophragmoides canariensis, Psammosphaera spp., and Psammolingulina papillosa were not previously found. The occurrence of these rare taxa could be the proxy of particular sea-floor conditions during the MPl3 zone, characterized by a locally active bottom circulation and mesotrophic waters.
PubDate: 2023-09-05
DOI: 10.54103/2039-4942/19905
Issue No: Vol. 129, No. 3 (2023)
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