scholarly journals Revision of the supposed Triassic, in fact Silurian genus Triadophyllum Weissermel, 1925 (Anthozoa, Rugosa)

Fossil Record ◽  
2007 ◽  
Vol 10 (2) ◽  
pp. 164-178
Author(s):  
D. Weyer
Keyword(s):  
Czech Republic ◽  
Cross Sections ◽  
Middle Triassic ◽  
Age Determination ◽  
Type Specimen ◽  
Southwestern Margin ◽  
Erratic Boulder

The only existing type specimen of <i>Triadophyllum posthumum</i> Weissermel, 1925 is not a Middle Triassic (middle Anisian, Pelsonian) Scleractinia, but a Silurian Rugosa collected from a Pleistocene erratic boulder of Baltoscandian origin. First serial cross sections demonstrate a synonymy of <i>Triadophyllum</i> Weissermel, 1925 with the worldwide distributed ahermatypic genus <i>Palaeocyathus</i> Foerste, 1888 (including also <i>Enterolasma</i> Simpson, 1900) known from Llandoverian/Wenlockian – Eifelian times. The species <i>Palaeocyathus posthumus</i> as well as the genus are still unknown in the classical Silurian sequences of Gotland and Estonia, which may be the possible origin of the glacial drift. At present, a more precise age determination within the Llandoverian, Wenlockian, or Ludlovian can not be achieved. The nearest certain occurrence of the genus is the early Wenlockian <i>Palaeocyathus conicus</i> (Bul'vanker, 1952) of Podolia (Ukraine), situated likewise on the southwestern margin of the ancient Baltoscandian shield; other records such as the Ludlovian <i>Palaeocyathus bohemicus</i> (Počta, 1902) from the Barrandian (Czech Republic) and <i>Palaeocyathus radiatus</i> (Münster, 1839) from Upper Franconia (Saxothuringia, Germany) are more distant on Gondwana-derived terranes. <br><br> Das allein existierende Holotypus-Polypar von <i>Triadophyllum posthumum</i> Weissermel, 1925 ist kein Scleractinia-Vertreter der Mittel-Trias (mittleres Anis, Pelson), sondern ein silurisches Rugosa-Taxon, das aus einem Pleistozän-Geschiebe baltoskandischen Ursprungs gesammelt wurde. Eine erste Querschliffserie belegt die Synonymie von <i>Triadophyllum</i> Weissermel, 1925 mit dem weltweit verbreiteten ahermatypischen Genus <i>Palaeocyathus</i> Foerste, 1888 (einschließlich <i>Enterolasma</i> Simpson, 1900), das aus dem Zeitraum Llandovery/Wenlock – Eifel bekannt ist. Die Art <i>Palaeocyathus</i> <i>posthumus</i> und auch das Genus wurden in den klassischen Silur-Schichtfolgen von Gotland und Estland noch nicht gefunden, die als Herkunftsgebiete der glazialen Drift in Betracht kommen. Momentan lässt sich keine präzisere Altersbestimmung innerhalb des Llandovery, Wenlock oder Ludlow erreichen. Das nächste Vorkommen der Gattung, das ebenfalls am SW-Rand des alten Baltoskandischen Schildes liegt, ist <i>Palaeocyathus conicus</i> (Bul'vanker, 1952) im unteren Wenlock von Podolien (Ukraine). Andere Nachweise wie <i>Palaeocyathus bohemicus</i> (Počta, 1902) aus dem Ludlov des Barrandium (Tschechische Republik) und <i>Palaeocyathus radiatus</i> (Münster, 1839) aus dem Ludlow von Oberfranken (Saxothuringikum, Deutschland) gehören zu primär entfernteren Terranes, die von Gondwana herkommen. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.200700006" target="_blank">10.1002/mmng.200700006</a>

Conodont Biostratigraphy and Age Determination of the Lower-Middle Triassic Boundary in South Guizhou Province, China

2011 ◽  
Vol 85 (2) ◽  
pp. 408-420 ◽  
Author(s):  
Jianxin YAO ◽  
Zhansheng JI ◽  
Liting WANG ◽  
Yanbin WANG ◽  
Zhenjie WU ◽  
...  
Keyword(s):  
Middle Triassic ◽  
Age Determination ◽  
Guizhou Province ◽  
Triassic Boundary ◽  
Conodont Biostratigraphy

scholarly journals Ontogeny of highly variable ceratitid ammonoids from the Anisian (Middle Triassic)

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10931
Author(s):  
Eva Alexandra Bischof ◽  
Nils Schlüter ◽  
Dieter Korn ◽  
Jens Lehmann
Keyword(s):  
Cross Sections ◽  
Middle Triassic ◽  
Phenotypic Variability ◽  
Taxonomic Diversity ◽  
Ontogenetic Changes ◽  
Knowledge Based ◽  
Ontogenetic Trajectories ◽  
Early Middle Triassic ◽  
First Time ◽  
High Diversity

Ammonoids reached their greatest diversity during the Triassic period. In the early Middle Triassic (Anisian) stage, ammonoid diversity was dominated by representatives of the family Ceratitidae. High taxonomic diversity can, however, be decoupled from their morphologic disparity. Due to its high phenotypic variability, the high diversity of ceratitids of the Anisian of Nevada was initially assumed to be caused by artificial over-splitting. This study aims to contribute data to settle this issue by applying geometric morphometrics methods, using landmarks and semi-landmarks, in the study of ontogenetic cross-sections of ammonoids for the first time. The results reveal that alterations in ontogenetic trajectories, linked to heterochronic processes, lead to the morphologic diversification of the species studied herein. Our knowledge, based on these ontogenetic changes, challenge the traditional treatment of species using solely adult characters for their distinction. This study furthermore demonstrates that the high diversity of the Anisian ammonoid assemblages of Nevada based on the traditional nomenclatoric approach is regarded to be reasonably accurate.

scholarly journals AGE DETERMINATION AND PALAEOGEOGRAPHIC RECONSTRUCTION OF PINDOS FORELAND BASIN BASED ON CALCAREOUS NANNOFOSSILS

2018 ◽  
Vol 36 (2) ◽  
pp. 864 ◽  
Author(s):  
I. Vakalas ◽  
G. Ananiadis ◽  
N. Kontopoulos ◽  
K. K. Stoykova ◽  
A. Zelilidis
Keyword(s):  
Cross Sections ◽  
Large Scale ◽  
Middle Eocene ◽  
Age Determination ◽  
Foreland Basin ◽  
Late Eocene ◽  
Early Miocene ◽  
Calcareous Nannofossils ◽  
Basin Fill

The study area is part of the Pindos foreland (Underhill, 1985). Pindos foreland is a tertiary turbiditic foreland basin fill trending parallel to the external Hellenides and occupies Gavrovo and Ionian isopic zones (Aubouin, 1959). The age of Pindos foreland sediments is still a matter of discussion. B.P. (1971) proposed an early Miocene to middle Miocene age, explaining the presence of Oligocene fauna as a product of large scale erosion and reworking of older sediments during Miocene. IGSR&IFP(1966) suggested a late Eocene to early Miocene age for the basin fill while Fleury (1980), Leigh (1991), Wilpshaar (1995), Bellas (1997) assigned an Oligocene age. Avramidis et al (1999) proposes a middle Eocene to early Miocene age assessment, using nannofosil zones from three studied cross sections in the Klematia-Paramythia basin (middle Ionian zone). The determination of the sediment ages was based on the study of calcareous nannofossils, which came from almost 120 samples covering 11 geological cross sections. The nannofosil marker species that were found in the samples were classified using the biozones proposed by Martini in 1971. According to the age assessments arose from the studied samples, clastic sedimentation in the study area began in the Middle Eocene, with small differences among the basin. The end of clastic sedimentation seems to be at different times in different parts of the basin.

Neutronic Analysis for VVER-440 Type Reactor Using PARCS Code

2018 ◽  
Author(s):  
Luca Ratti ◽  
Guido Mazzini ◽  
Marek Ruščák ◽  
Valerio Giusti
Keyword(s):  
Czech Republic ◽  
Cross Sections ◽  
Nuclear Power ◽  
Power Plants ◽  
Computational Models ◽  
Reactor Core ◽  
Sensitivity Study ◽  
The Czech Republic ◽  
State Office ◽  
Scale Models

The Czech Republic National Radiation Protection Institute (SURO) provides technical support to the Czech Republic State Office for Nuclear Safety, providing safety analysis and reviewing of the technical documentations for Nuclear Power Plants (NPPs). For this reason, several computational models created in SURO were prepared using different codes as tools to simulate and investigate the design base and beyond design base accidents scenarios. This paper focuses on the creation of SCALE and PARCS neutronic models for a proper analysis of the VVER-440 reactor analysis. In particular, SCALE models of the VVER-440 fuel assemblies have been created in order to produce collapsed and homogenized cross sections necessary for the study with PARCS of the whole VVER-440 reactor core. The sensitivity study of the suitable energy threshold to be adopted for the preparation with SCALE of collapsed two energy-group homogenized cross sections is also discussed. Finally, the results obtained with PARCS core model are compared with those reported in the VVER-440 Final Safety Report.

scholarly journals Growth increment periodicity in the shell of the razor clam <i>Ensis directus</i> using stable isotopes as a method to validate age

2013 ◽  
Vol 10 (7) ◽  
pp. 4741-4750 ◽  
Author(s):  
J. F. M. F. Cardoso ◽  
G. Nieuwland ◽  
R. Witbaard ◽  
H. W. van der Veer ◽  
J. P. Machado
Keyword(s):  
Cross Sections ◽  
Age Determination ◽  
Growth Increment ◽  
Annual Growth ◽  
Threshold Temperature ◽  
Growth Line ◽  
Razor Clam ◽  
Oxygen And Carbon Isotope ◽  
Reconstructed Temperature ◽  
Correct Estimation

Abstract. To evaluate the role of the razor clam Ensis directus in Dutch coastal waters, understanding its population dynamics is important. As such, the age structure of the population forms a key parameter. Accurate age determination in bivalve shells is not always straightforward due to the difficulty of interpreting externally visible growth lines. In the present paper, we aimed at validating the seasonality in growth line formation using visual techniques in combination with stable oxygen and carbon isotope analyses (δ18O and δ13C). High δ18O values in the shell coincided with growth marks on the external surface of the valve and in acetate peels of the shell's cross section. Most shell δ18O samples were assigned to the months from June to September. From November to March no samples were retrieved, indicating that the shell did not grow. The lowest reconstructed temperature (6.3 °C) suggests that ~ 6 °C may be the threshold temperature for growth. Nevertheless, most of the reconstructed values fell above 14.5 °C, indicating that growth occurred mainly in the summer at relatively high temperatures. Shell δ13C profiles followed a more or less seasonal cycle, but no direct relationship could be made between δ13C values and annual growth lines. Although counting external annual growth lines led to a correct estimation of age and consequently of growth rates, we recommend analysing acetate peels of cross sections to support the distinction between annual lines and disturbance lines.

Marginal Parenchyma Bands and Crystalliferous Chains as Indicators of Age in African Acacia Species

IAWA Journal ◽  
1991 ◽  
Vol 12 (2) ◽  
pp. 187-194 ◽  
Author(s):  
Ian D. Gourlay ◽  
Peter J. Kanowski
Keyword(s):  
Cross Sections ◽  
Age Determination ◽  
Growth Phases ◽  
Growth Rings ◽  
Rainfall Distribution ◽  
Acacia Species ◽  
Narrow Bands

The radial cross sections of wood samples from individuals of known age in six African Acacia species were examined for growth rings, which were apparent in most species as narrow bands of marginal parenchyma filled with long crystal chains. The number of bands formed annually corresponded to the number of peaks in rainfall distribution. Samples from specimens of African Acacia species from the Oxford Forestry Institute's xylarium (FHOw) were also examined for similar crystalliferous chains, which were generally present. These results suggest that marginal parenchyma bands and crystalliferous chains define growth phases in African Acacia species, and may therefore be useful for age determination.

Age Determination of Male Bufo bufo (Amphibia, Anura) from the Netherlands, based on Year Rings in Phalanges

1980 ◽  
Vol 1 (3) ◽  
pp. 223-233 ◽  
Author(s):  
Agnes S. M. Hemelaar
Keyword(s):  
The Netherlands ◽  
Cross Sections ◽  
Age Determination ◽  
Bufo Bufo ◽  
First Year ◽  
The Common ◽  
One Year ◽  
Toad Bufo ◽  
Toad Bufo Bufo

AbstractBased on both the pattern of year rings in a particular phalanx of adult male specimens of the common toad Bufo bufo and the thickness of this bone in first-year toads, the rate of resorption of year rings in each toad could be assessed. It appeared that this rate of resorption is small. Therefore the age of male specimens of Bufo bufo from the Netherlands can be determined for about 92% by counting the number of year rings in hematoxylin-stained cross-sections of this particular phalanx. This percentage can be raised to 93-98% by considering the year rings resorbed. The age of the remaining toads may be underestimated by not more than one year.

Age Determination of Lingcod (Ophiodon elongatus) Using Dorsal Fin Rays and Scales

1977 ◽  
Vol 34 (9) ◽  
pp. 1305-1313 ◽  
Author(s):  
Richard J. Beamish ◽  
D. Chilton
Keyword(s):  
Key Words ◽  
Cross Sections ◽  
Age Determination ◽  
Fish Length ◽  
Dorsal Fin ◽  
Ophiodon Elongatus ◽  
Fin Ray ◽  
Fin Rays ◽  
Key Words Age

Cross sections of the 4th–8th fin rays from the second dorsal fin provided reliable ages of lingcod (Ophiodon elongatus), although there was some difficulty interpreting the ages of 1- and 2-yr-old fish. Length was an acceptable indicator of age 1- and 2-yr-old fish. After a scale age of 5 or 6 yr, the scale annulus became difficult to identify. After age 7 or about 75–85 cm, fin-ray ages were older than scale ages. Some of the oldest fish averaged 8 yr older by the fin-ray method.Mature females attained much larger mean sizes than males of similar age, and there was considerable variation in size of similar-aged older fish. Key words: Age determination, fin rays, scales, Ophiodon elongatus, ageing errors.

Calcium Oxalate Crystals in African Acacia Species and Them Analysis by Scanning Proton Microprobe (Spm)

IAWA Journal ◽  
1994 ◽  
Vol 15 (2) ◽  
pp. 137-148 ◽  
Author(s):  
I.D. Gourlay ◽  
G.W. Grime
Keyword(s):  
Calcium Oxalate ◽  
Cross Sections ◽  
Chemical Elements ◽  
Age Determination ◽  
Annual Rainfall ◽  
Growth Rings ◽  
Proton Microprobe ◽  
Scanning Proton Microprobe ◽  
Individual Trees ◽  
Narrow Bands

The radial and cross sections of wood samples from individual trees of known age of African Acacia species were examined for growth rings. These were apparent in most species as narrow bands of marginal parenchyma filled with long crystal chains. The crystals were subsequently identified as calcium oxalate through the use of a scanning proton microprobe. Several other chemical elements were concentrated around this zone. The number of parenchyma bands formed annually corresponded to the number of peaks in the annual rainfall distribution. These results suggest that the presence of marginal parenchyma bands and crystalliferous chains define growth phases in African Acacia species, and can be used for age determination.

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